Organic light-emitting element

Abstract

To provide an organic light-emitting element with excellent drive durability characteristics.SOLUTION: The organic light-emitting element has a first electrode, a light-emitting layer, and a second electrode. The light-emitting layer includes at least a first compound formed by bonding by a single bond a naphthalene ring and a fused polycyclic ring of three or more rings and a second compound formed by further cyclizing a naphthalene ring and a fused polycyclic ring of the first compound.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an organic light-emitting element, and an apparatus or device using the organic light-emitting element. [Background technology]

[0002] An organic light-emitting element (hereinafter sometimes referred to as an "organic electroluminescence element" or "organic EL element") is an electronic element having a pair of electrodes and an organic compound layer disposed between the electrodes. By injecting electrons and holes from the pair of electrodes, excitons of a light-emitting organic compound in the organic compound layer are generated, and when the excitons return to the ground state, the organic light-emitting element emits light. Recent progress in organic light-emitting devices has been remarkable, including low driving voltage, diverse emission wavelengths, high-speed response, and the possibility of making light-emitting devices thinner and lighter. Incidentally, the creation of compounds suitable for organic light-emitting devices has been actively carried out up to now. This is because the creation of compounds with excellent durability is important for providing high-performance organic light-emitting devices. Compounds in which a condensed polycyclic group is substituted on a naphthalene ring have been created so far, and the following compound 1-A is described in Patent Document 1.

[0003] [ka] [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-123917 A Summary of the Invention [Problem to be solved by the invention]

[0005] A synthesis example of the above compound 1-A and its usefulness as a host material are shown in Patent Document 1. However, improvement in durability under continuous driving conditions at a constant current is desired. The present invention has been made to solve the above problems, and an object of the present invention is to provide an organic light-emitting device having excellent driving durability characteristics. [Means for solving the problem]

[0006] The present invention provides an organic light-emitting device having a first electrode, an organic compound layer, and a second electrode, The organic compound layer is characterized by having at least a layer containing a first compound represented by the following general formula [1] and a second compound represented by the following general formula [2].

[0007] [ka] (In the general formulas [1] and [2], R1 to R7 are each independently selected from a hydrogen atom, a deuterium atom, a linear, branched or cyclic substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group, and Ar1 is a substituted or unsubstituted fused polycyclic group having three or more rings.) Effect of the Invention

[0008] According to the present invention, an organic light-emitting element having excellent luminous efficiency and driving durability characteristics is provided, and by using the organic light-emitting element, it is possible to provide an excellent device or apparatus such as a light-emitting display device. [Brief description of the drawings]

[0009] [Figure 1] This is a diagram showing the electron orbitals of the LUMO of the first and second compounds according to the present invention and a comparative compound, calculated by molecular orbital calculation. [Diagram 2] 1A is a schematic cross-sectional view showing an example of a pixel of a display device according to one embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view showing an example of a display device using an organic light-emitting element according to one embodiment of the present invention. [Diagram 3]FIG. 1 is a schematic diagram illustrating an example of a display device according to an embodiment of the present invention. [Figure 4] 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. [Diagram 5] 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 6] 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 a moving body having a vehicle lamp according to an embodiment of the present invention. [Figure 7] 1A is a schematic diagram showing an example of a wearable device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram showing another example of a wearable device according to an embodiment of the present invention. [Figure 8] 1A is a schematic diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention, and FIG. 1B is a schematic diagram illustrating an example of an exposure light source of the image forming apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention is an invention for providing an organic light-emitting element with a long life. In order to achieve a long life of an organic light-emitting element, it is necessary to prevent the deterioration of the organic materials in the element, particularly the organic materials used in the light-emitting layer. In general, in order to extend the life of an organic light-emitting element, it is effective to expand the recombination region and prevent the deterioration caused by the concentration of exciton generation. When the exciton generation is concentrated, energy transfer occurs from another excited molecule to an excited molecule, resulting in a transition to a higher energy state. In the high energy state, if a situation occurs in which the bond energy of the single bond site in the molecular structure is exceeded, the bond is cleaved and decomposition products are generated, causing brightness deterioration. In order to avoid this, it is effective to disperse the exciton generation.

[0011] In addition, when a current is continuously applied at a high current density, the probability of collision between the continuously generated excitons and cation radicals or anion radicals generated by electrons or holes increases. These radical species become active species for the excitons and cause quenching, so it is necessary to reduce the probability of collision between the excitons and charges, especially at high current densities. In the present invention, it is considered that a method of reducing this collision probability is effective in which the light-emitting layer is configured to include a material that has the same partial structure as the host material, has higher electron acceptance than the host material, and is not involved in light emission, thereby controlling charge injection into the light-emitting layer and reducing the probability of collision between the charges and the excitons.

[0012] The present invention is characterized in that the organic compound layer has a layer containing a first compound represented by the following general formula [1] and a second compound represented by the following general formula [2]. Both the first compound and the second compound are organic compounds.

[0013] [ka]

[0014] In the above general formulas [1] and [2], R1 to R7 are each independently selected from a hydrogen atom, a deuterium atom, a linear, branched or cyclic substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group, and Ar1 is a substituted or unsubstituted fused polycyclic group having three or more rings. The characteristics of the light-emitting layer will be described below by taking as an example a preferred embodiment in which the light-emitting layer contains a first compound, a second compound, and a light-emitting material.

[0015] [1] The LUMO level of the second compound is lower than that of the first compound (in the direction away from the vacuum level) and is also lower than that of the light-emitting material (in the direction away from the vacuum level), i.e., the second compound has the highest electron-accepting property in the light-emitting layer. In other words, the LUMO energy levels of the first compound, the second compound, and the light-emitting material are designated as LUMO1, LUMO2, LUMO3, LUMO4, LUMO5, LUMO6, LUMO7, LUMO8, LUMO9, LUMO10, LUMO11, LUMO12, LUMO13, LUMO14, LUMO15, LUMO16, LUMO17, LUMO18, LUMO19, LUMO111, LUMO112, LUMO113, LUMO114, LUMO115, LUMO116, LUMO117, LUMO118, LUMO119, LUMO119, LUMO119, LUMO119, LUMO119, LUMO119, LUMO119, LUMO120, LUMO121, LUMO122, LUMO123, LUMO124, LUMO125, LUMO126, LUMO127, LUMO128, LUMO130, LUMO131, LUMO132, LUMO133, LUMO134, LUMO135, LUMO136, LUMO137, LUMO138, LUMO139, LUMO140, LUMO141, LUMO142, LUMO143, LUMO144, LUMO145, LUMO146, LUMO147, LUMO148, E When this is done, the following formula [A] is satisfied. |LUMO2|>|LUMOE |>|LUMO1| [A]

[0016] Table 1 below shows an example of this embodiment, in which Ar1 is 1-pyrene in general formula [1] and Ar1 is 1,10-pyrene in general formula [2], R1 to R5 and R7 are substituted with hydrogen, and R6 is substituted with 2-naphthalene. Comparative Example A shows a configuration that does not include the second compound, and Comparative Example B shows a configuration in which the second compound does not correspond to general formula [2] and is a compound having a structure in which pyrene forms a ring with the 2- and 3-positions of naphthalene.

[0017] Table 1 shows the calculated values ​​of the LUMO levels of the first compound, the second compound, and the light-emitting material, the difference between the calculated values ​​of the LUMO levels of the first compound and the second compound as ΔLUMO1, and the difference between the calculated values ​​of the LUMO levels of the first compound and the light-emitting material as ΔLUMO2. 2 The time it takes for the luminance to deteriorate by 5% when a current is continuously applied at a current density of 1000 mA, and is shown as a relative value based on the value of Comparative Example A.

[0018] [Table 1]

[0019] As shown in Table 1, in the present invention 1-1, the presence of the second compound whose LUMO level is lower than that of the first compound and the light-emitting material (in the direction away from the vacuum level) results in ΔLUMO2<ΔLUMO1, and the second compound becomes the most electron-accepting compound in the light-emitting layer, and it can be seen that the durability life is improved. In Comparative Example A, the light-emitting material is responsible for electron acceptance and at the same time emits light through an excitation process, so that the collision probability between excitons and electrons increases in the high current density region, causing quenching. On the other hand, in the present invention 1-1, the second compound whose LUMO level is lower than that of the light-emitting material (in the direction away from the vacuum level) is introduced into the light-emitting layer, thereby avoiding charge concentration in the light-emitting material and reducing the collision probability between excitons and electrons, thereby suppressing exciton decomposition.

[0020] In addition, in Comparative Example B, the second compound has a higher LUMO level than the light-emitting material (approaching the vacuum level), and does not play a role in preventing charge concentration in the light-emitting material, so there is no effect of improving the lifetime, and instead there is a tendency for the lifetime to decrease. This is because the second compound in Comparative Example B does not satisfy the requirements necessary for the present invention. This will be explained next.

[0021] [2] The second compound has a low oscillator strength and does not participate in emission. As shown in Table 1, the oscillator strength (calculated value) of the second compound shown in the present invention 1-1 is 0.07. The oscillator strength is a value indicating the transition probability from the ground state to the excited state, and when it is less than 0.1, the transition probability is very small, so it does not participate in light emission. Therefore, the second compound of the present invention 1-1 only has the function of trapping charges and plays a role in avoiding charge concentration from excitons. On the other hand, the oscillator strength (calculated value) of the second compound used in the comparative example B is 0.44, and has a certain degree of transition probability, so it participates in light emission. Therefore, in the comparative example B, not only the luminescent material but also the second compound emits light, and the stability of the second compound is inferior to that of the luminescent material, so the LT95 is even lower than that of the comparative example A that does not have the second compound. In Comparative Example B in Table 1, since ΔLUMO1<ΔLUMO2, the light-emitting material has the highest electron accepting property, and the effect of the second compound is slight.

[0022] Table 2 shows organic light-emitting devices that have the same configuration as Invention 1-1 and Comparative Examples A and B in Table 1, except that the light-emitting material was changed to a compound with reduced electron-accepting property. As shown in Table 2, Comparative Example D, in which ΔLUMO1>ΔLUMO2, shows a more significant difference from Invention 1-2, which used the second compound represented by general formula [2].

[0023] [Table 2]

[0024] It can be seen that ΔLUMO1>ΔLUMO2 is the same not only in the present invention 1-2 but also in the comparative example D, but the difference in LT95 is larger than that in Table 1. Since ΔLUMO1>ΔLUMO2, the second compound is the most electron-accepting compound in both the present invention 1-2 and the comparative example D, and the combination avoids charge concentration in the light-emitting material. However, in the comparative example D, the second compound has an oscillator strength similar to that of the light-emitting material, so the second compound itself is involved in light emission. Therefore, in the comparative example D, the collision probability between the exciton generation and the electron in the second compound increases, which promotes the decomposition of the exciton, resulting in a decrease in the life. On the other hand, the second compound of the present invention 1-2 has a low oscillator strength, so the transition probability is low and it is not involved in light emission. Therefore, since there is no generation of excitons in the second compound, only the light-emitting material generates excitons in the light-emitting layer, and since the second compound traps the charge, the collision probability between the exciton and the charge can be reduced, so the life is improved.

[0025] [3] The second compound has the same partial structure as the first compound.

[0026] Table 3 shows an organic light-emitting device having the same configuration as invention 1-2 in Table 2 except that a compound having a significantly different structure from the first compound was used as the second compound, together with invention 1-2 and Comparative Example C in Table 2.

[0027] [Table 3]

[0028] The first compound and the second compound according to the present invention are compounds that mainly play a role in charge transfer in the light-emitting layer. Even if ΔLUMO1>0 as shown in Table 3, if the structures of the first compound and the second compound are significantly different, the effect of improving the lifespan cannot be obtained as shown in Comparative Example E. In this embodiment, it is preferable to use the first compound as a host and the second compound as an assist, but as shown in Invention 1-2, these two materials have a common partial structure, so that excess charge accumulation does not occur in the light-emitting layer. Furthermore, because ΔLUMO1>0, electron trapping to the second compound and popping when the trapped electrons move back to the first compound are smoothly performed.

[0029] FIG. 1 shows the LUMO electron orbitals of the first and second compounds of the present invention 1-2 and Comparative Example E in Table 3, calculated by molecular orbital calculation. As shown in FIG. 1, the first and second compounds have a common partial structure, so that the distribution of the LUMO electron orbitals of the first and second compounds is similar, and therefore the overlap of the LUMO wave functions of the first and second compounds is large, and charge transfer between the compounds is easy. On the other hand, in Comparative Example E, the structures of the first and second compounds are different from each other, so that the distribution of the LUMO electron orbitals of the first and second compounds is different, as shown in FIG. 1, so that the wave functions of the LUMOs are different, and as a result, the overlap is small, and a barrier is generated in the transfer of charge. This barrier becomes a charge accumulation, and the collision probability of the charge with the excitons generated in the light-emitting layer increases, leading to the annihilation of the excitons, and the life is reduced.

[0030] From the above, the present inventors have found that by configuring an emission layer to contain a second compound which has the same partial structure as a first compound, has a higher electron accepting property than the first compound, and is not involved in light emission, charge injection into the emission layer can be controlled and the probability of collision between charges and excitons can be reduced, thereby improving the durability of the device.

[0031] The above calculation results were visualized using molecular orbital calculations. The calculation method used for the molecular orbital calculations was the density functional theory (DFT), which is currently widely used. The functional was B3LYP, and the basis set was 6-31G. *It is also a smooth-flowing waveguide called Gaussian09(Gaussian09, RevisionC.01,MJFrisch,GWTrucks,HBSchlegel,GEScuse ria, MARobb,JRCheeseman,G.Scalmani,V.Barone,B.Mennucci,GAPetersson,H.Nakatsuji,M.Caricato,X.Li,HPHra tchian, AFIzmaylov, J. Bloino, G. Zheng, JLSonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishi da,T.Nakajima,Y.Honda,O.Kitao,H.Nakai,T.Vreven,JAMontgomery,Jr.,JEPeralta,F.Ogliaro,M.Bearpark,JJHe yd, E. Brothers, KNKudin, VNS Taroverov, T. Keith, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, JCBurant ,SSIyengar,J.Tomasi,M.Cossi,N.Rega,JMMillam,M.Klene,JEKnox,JBCross,V.Bakken,C.Adamo,J.Jaramillo,R.G omperts,REStratmann,O.Yazyev,AJAustin,R.Cammi,C.Pomelli,JWOchterski,RLMartin,K.Morokuma,VGZakrzews ki,GAVoth,P.Salvador,JJDannenberg,S.Dapprich,ADDaniels,O.Farkas,JBForesman,JVOrtiz,JCioslowski,and DJFox,Gaussian,Inc.,Wallingford CT,2010.)

[0032] If you want to check the specifications of the keyboard [1], it is possible The contents of this file can be stored in the table of contents [2]. In general formula [1] and general formula [2], R1 to R7 are each independently selected from a hydrogen atom, a deuterium atom, a linear, branched or cyclic substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group, and the ring Ar1 is a substituted or unsubstituted fused polycyclic group having three or more rings.

[0033] The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-decyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-octyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclohexylmethyl, cyclohexylethyl, 4-fluorocyclohexyl, norbornyl, and adamantyl. The alkyl group may have a substituent and may have a halogen atom. When the alkyl group has a halogen atom, the halogen atom is preferably a fluorine atom. Specific examples include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a 2-fluoroethyl group, a 2,2,2-trifluoroethyl group, a perfluoroethyl group, a 3-fluoropropyl group, a perfluoropropyl group, a 4-fluorobutyl group, a perfluorobutyl group, a 5-fluoropentyl group, and a 6-fluorohexyl group.

[0034] The aryl group is preferably an aryl group having 6 to 24 carbon atoms. Specific examples include, but are not limited to, a phenyl group, a naphthyl group, an indenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, an anthryl group, a phenanthryl group, a pyrenyl group, a tetracenyl group, a pentacenyl group, a triphenylenyl group, and a perylenyl group.

[0035] The heterocyclic group is preferably a heterocyclic group having 3 to 21 carbon atoms. Examples of heteroatoms include oxygen, nitrogen, and sulfur. Specific examples include a thienyl group, a pyrrolyl group, a pyridyl group, a pyrazyl group, a pyrimidyl group, a pyridazinyl group, a quinolinyl group, an isoquinolinyl group, an oxazolyl group, an oxadiazolyl group, a phenanthridinyl group, an acridinyl group, a naphthyridinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a phthalazinyl group, a phenanthrolyl group, a phenazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a carbazolyl group, a benzofuranyl group, a benzothiophenyl group, an indolyl group, a cycloazinyl group, a benzimidazolyl group, a benzothiazolyl group, and a benzothiadiazolyl group, but are not limited thereto.

[0036] In the above-mentioned fused polycyclic group having three or more rings, the same fused polycyclic ring is monovalent in the general formula [1], and is bivalent in the general formula [2], and is bonded to the naphthalene skeleton as a substituent. Therefore, the fused polycyclic group having three or more rings in the general formulas [1] and [2] is described as the fused polycyclic ring name + group, including both monovalent and bivalent. Preferred fused polycyclic groups include anthracene group, phenanthrene group, pyrene group, fluoranthene group, benzophenanthrene group, tetracene group, pentacene group, perylene group, etc., but are not limited thereto.

[0037] In the above general formulas [1] and [2], examples of the substituents further possessed by the above-mentioned alkyl group, aryl group, heterocyclic group, and condensed polycyclic group include alkyl groups having 1 to 6 carbon atoms, such as methyl group, ethyl group, propyl group, and butyl group, aralkyl groups such as benzyl group, aryl groups having 6 to 12 carbon atoms, such as phenyl group and biphenyl group, heterocyclic groups having 3 to 9 carbon atoms, such as pyridyl group, pyrrolyl group, benzimidazolyl group, and benzothiazolyl group, amino groups such as dimethylamino group, diethylamino group, dibenzylamino group, diphenylamino group, and ditolylamino group, alkoxyl groups such as methoxyl group, ethoxyl group, propoxyl group, and phenoxyl group, cyano group, halogen atoms such as fluorine atom, and deuterium, etc. Examples of the heteroatom of the above-mentioned heterocyclic group include oxygen, nitrogen, and sulfur.

[0038] The first compound according to the present invention is preferably a compound represented by the following general formula [3], and the second compound is preferably a compound represented by the following general formula [4]. It is also preferable that R5 is a pyrenyl group, or R6 is any one of a fluorenyl group, a naphthyl group, a phenyl group, and a dibenzothiophenyl group.

[0039] [ka]

[0040] In the above general formulas [3] and [4], R1, R2, and R4 to R 15 are each independently selected from a hydrogen atom, a linear, branched or cyclic alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. Preferred examples of the alkyl group, aryl group, and heterocyclic group are the same as those given as the alkyl group, aryl group, and heterocyclic group in the above general formulas [1] and [2].

[0041] Specific examples of the first compound and the second compound according to the present invention are shown below, but the present invention is not limited thereto.

[0042] [Table 4]

[0043] [Table 5]

[0044] [Table 6]

[0045] [Table 7]

[0046] [Table 8]

[0047] Among the above-mentioned exemplary compounds, the exemplary compounds belonging to group A are those in which Ar1 in the general formula [1] and the general formula [2] is a pyrene group and sp 3 (sp 3 It is a compound that does not contain hybrid orbital carbon and is an organic compound that has excellent stability against holes and electrons. Among the above-mentioned exemplary compounds, the exemplary compounds belonging to group B are compounds in which Ar1 in general formula [1] and general formula [2] is a pyrene group and has an alkyl group as a substituent, and have excellent sublimation properties. In addition, the organic light-emitting device containing such exemplary compounds in the light-emitting layer can be made to operate at a lower voltage. Among the above exemplary compounds, the exemplary compounds belonging to group C are compounds in which Ar1 in general formula [1] and general formula [2] is a pyrene group and has a heteroatom in a condensed ring, and have excellent charge transport properties.

[0048] Among the above exemplary compounds, the exemplary compounds belonging to group D have excellent heat resistance because Ar1 in general formula [1] and general formula [2] is a chrysene group. Among the above exemplary compounds, the exemplary compounds belonging to group E have excellent electron accepting properties because Ar1 in general formula [1] and general formula [2] is a fluoranthene group. Among the above-mentioned exemplary compounds, the exemplary compounds belonging to group F have excellent heat resistance because Ar1 in general formula [1] and general formula [2] is a benzophenanthrene group. Among the above exemplary compounds, the exemplary compounds belonging to group G have an anthracene group as Ar1 in the general formula [1] and the general formula [2], and are excellent in charge transportability.

[0049] The organic light-emitting element according to this embodiment has at least a pair of electrodes, an anode and a cathode, and an organic compound layer disposed between these electrodes. In the organic light-emitting element according to this embodiment, the organic compound layer may be a single layer or a laminate consisting of multiple layers as long as it has a light-emitting layer. Here, the multiple layers refer to a state in which a light-emitting layer and another light-emitting layer are laminated. The laminate refers to the organic compound layers being laminated from electrode to electrode.

[0050] Here, when the organic compound layer is a laminate consisting of multiple layers, the organic compound layer 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, etc. in addition to the light emitting layer. The light emitting layer may be a single layer or a laminate consisting of multiple layers. When the organic compound layer is a multi-layer structure, the layers may be, from the anode side, a hole injection layer, a hole transport layer, an electron blocking layer, a light emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer.

[0051] The electron blocking layer preferably has a LUMO level higher than that of the light-emitting layer. This is to suppress the movement of electrons from the light-emitting layer to the anode side. HOMO and LUMO are the highest occupied molecular orbital and the lowest unoccupied molecular orbital, respectively, and their respective energy levels are referred to as the HOMO level and the LUMO level. The HOMO level and the LUMO level may also be referred to as HOMO and LUMO, respectively. A high HOMO level or a high LUMO level indicates a state closer to a vacuum level. A high HOMO level is also referred to as a shallow HOMO level. The same applies to the LUMO level.

[0052] At least one of the organic compound layers of the organic light-emitting device according to this embodiment contains a first compound represented by general formula [1] and a second compound represented by general formula [2]. Specifically, the first and second compounds are contained in any of the above-mentioned light-emitting layer, hole injection layer, hole transport layer, electron blocking layer, hole blocking layer, electron transport layer, electron injection layer, etc. The first and second compounds are preferably contained in the light-emitting layer.

[0053] In the organic light-emitting device of this embodiment, when the first and second compounds are contained in the light-emitting layer, the third compound contains a light-emitting material. Specifically, the first compound is a host, the second compound is an assistant, and the third compound is a guest. In addition to the light-emitting layer containing the first and second compounds and the light-emitting material, a second light-emitting layer may be provided, and the second light-emitting layer is preferably disposed on the anode side.

[0054] Here, the host is the compound with the largest mass ratio among the compounds constituting the light-emitting layer. The guest is a compound with a smaller mass ratio than the host among the compounds constituting the light-emitting layer, and is a compound that is responsible for the main emission of light. The guest is also called a dopant. The assist is a compound with a smaller mass ratio than the host among the compounds constituting the light-emitting layer, and assists the emission of the guest. The assist is also called a second host. When the first compound is used as the host and the second compound is used as the assist, the content of the second compound is more than 0 and less than 0.2 mass%, preferably less than 0.1 mass%, with the total of the first compound and the second compound being 100 mass%. In addition, the total content of the first compound and the second compound in the light-emitting layer is preferably 80% by weight or more and 99% by weight or less.

[0055] The present inventors have conducted various studies and found that when a first compound represented by the general formula [1] and a second compound represented by the general formula [2] are used in combination in an organic compound layer of an organic light-emitting device, a highly durable device can be obtained. The organic compound layer has a light-emitting layer, and the light-emitting layer may contain light-emitting materials having a plurality of light-emitting colors. In addition, by combining a plurality of light-emitting colors, it is possible to make the light-emitting device emit white light.

[0056] The structure of the organic light-emitting device according to the present embodiment is not limited to the above-mentioned structure. For example, various layer structures may be used, such as providing an insulating layer at the interface between the electrode and the organic compound layer, providing an adhesive layer or an interference layer, or the electron transport layer or the hole transport layer being composed of two layers having different ionization potentials.

[0057] The light extraction structure of the organic light emitting element may be a top emission type in which light is extracted from the electrode on the opposite side to the substrate, a bottom emission type in which light is extracted from the substrate side, or a double-sided extraction structure. When light is extracted from the substrate side, the substrate and the electrode on the substrate side are preferably light-transmitting. When light is extracted from the opposite side to the substrate, the electrode on the opposite side to the substrate is preferably light-transmitting.

[0058] In addition to the first compound represented by the general formula [1] and the second compound represented by the general formula [2], the organic light-emitting device according to this embodiment can also use conventionally known compounds as necessary. Specifically, the conventional compounds include low-molecular-weight and high-molecular-weight hole-injecting or hole-transporting compounds, host compounds, light-emitting materials, electron-injecting or electron-transporting compounds, etc. Examples of these compounds are given below.

[0059] The hole injection / transport material is preferably a material having high hole mobility so as to facilitate the injection of holes from the anode and transport the injected holes to the light-emitting layer, and is preferably a material having a high glass transition temperature so as to suppress deterioration of the film quality, such as crystallization, in the organic light-emitting element. Examples of low molecular and high molecular materials having 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 the electron blocking layer. Specific examples of compounds usable as the hole injection transport material are shown below, but the invention is not limited to these.

[0060] [ka]

[0061] Among the above, HT16 to HT18 can reduce the driving voltage by using them in the layer in contact with the anode. HT16 is widely used in organic light-emitting elements. HT2, HT3, HT10, and HT12 may be used in the organic compound layer adjacent to HT16. Also, a plurality of materials may be used in one organic compound layer. For example, combinations of HT2 and HT4, HT3 and HT10, and HT8 and HT9 may be used.

[0062] Examples of luminescent materials mainly involved in luminescence function include condensed ring compounds (e.g., fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene compounds, rubrene, etc.), quinacridone derivatives, coumarin derivatives, stilbene derivatives, organic aluminum 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. Here, a derivative is a compound whose skeleton can be found in the structure. For example, the following BD3 can be said to be a fluorene derivative. Also, BD6, BD7, GD4, and RD1 can be said to be fluoranthene derivatives. GD1, GD2, and GD3 can be said to be anthracene derivatives. GD4 is an anthracene derivative as well as a pyrene derivative. Among them, fluoranthene derivatives, anthracene derivatives, and pyrene derivatives are preferable. When a plurality of light-emitting materials are used, it is preferable that all of the light-emitting materials are fluorentene derivatives, anthracene derivatives, or pyrene derivatives. Specific examples of compounds that can be used as the light-emitting material are shown below, but the present invention is not limited to these.

[0063] [ka]

[0064] Examples of the host and assist contained in the light-emitting layer include carbazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organic aluminum complexes such as tris(8-quinolinolato)aluminum, organic beryllium complexes, etc. These compounds are also suitable for use in the hole-blocking layer. Specific examples of the compound used as the host in the light-emitting layer are shown below, but the present invention is not limited thereto.

[0065] [ka]

[0066] The electron transporting 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 transporting 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, organic aluminum complexes, and condensed ring compounds (e.g., fluorene derivatives, naphthalene derivatives, chrysene derivatives, anthracene derivatives, etc.). Furthermore, the above electron transporting materials are also preferably used in the hole blocking layer. Specific examples of compounds used as electron transporting materials are shown below, but are of course not limited to these.

[0067] [ka]

[0068] The electron injection material can be selected from those that can easily inject electrons from the cathode, and is selected in consideration of the balance with hole injection properties. Organic compounds include n-type dopants and reducing dopants. For example, compounds containing alkali metals such as lithium fluoride, lithium complexes such as lithium quinolinol, benzimidazolidene derivatives, imidazolidene derivatives, fulvalene derivatives, and acridine derivatives can be mentioned.

[0069] <Configuration of organic light-emitting element> The organic light-emitting element is provided by forming an insulating layer, a first electrode, an organic compound layer, and a second electrode on a substrate. A protective layer, a color filter, a microlens, etc. may be provided on the second electrode. When a color filter is provided, a planarizing layer may be provided between the protective layer. The planarizing layer may be made of acrylic resin, etc. The same applies when a planarizing layer is provided between the color filter and the microlens.

[0070] [substrate] Examples of the substrate include quartz, glass, silicon wafer, resin, and metal. In addition, a switching element such as a transistor and wiring may be provided on the substrate, and an insulating layer may be provided thereon. As the insulating layer, any material can be used as long as it can form a contact hole so that wiring can be formed between the first electrode and the insulating layer, and insulation from wiring that is not connected can be ensured. For example, resin such as polyimide, silicon oxide, silicon nitride, etc. can be used.

[0071] [electrode] A pair of electrodes can be used. 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.

[0072] The material constituting the anode should have as large a work function as possible. For example, metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, tungsten, etc., mixtures containing these metals, alloys combining these metals, 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, and polythiophene can also be used. These electrode materials may be used alone or in combination of two or more kinds. The anode may be composed of one layer or multiple layers.

[0073] When used as a reflective electrode, for example, chromium, aluminum, silver, titanium, tungsten, molybdenum, or alloys or laminates thereof can be used. The above materials can also function as a reflective film without serving as an electrode. When used as a transparent electrode, a transparent conductive layer of oxide such as indium tin oxide (ITO) or indium zinc oxide can be used, but is not limited to these. Photolithography technology can be used to form the electrode.

[0074] The material for the cathode should have a small work function. Examples of the material include alkali metals such as lithium, alkaline earth metals such as calcium, aluminum, titanium, manganese, silver, lead, chromium, and other metals or mixtures containing these metals. Alternatively, alloys of these metals can be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, zinc-silver, and the like can be used. Metal oxides such as indium tin oxide (ITO) can also be used. These electrode materials may be used alone or in combination of two or more types. The cathode may have a single layer structure or a multi-layer structure. Among these, it is preferable to use silver, and it is even more preferable to use a silver alloy to reduce the aggregation of silver. As long as the aggregation of silver can be reduced, the ratio of the alloy is not important. For example, the ratio of silver to other metals may be 1:1, 3:1, and the like.

[0075] 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 it is more preferable to use a direct current or alternating current sputtering method, etc., since the film coverage is good and the resistance can be easily reduced.

[0076] [Organic compound layer] The organic compound layer has at least a light-emitting layer, and may have a hole injection layer, a hole transport layer, and an electron blocking layer on the anode side, and a hole blocking layer, an electron transport layer, an electron injection layer, and the like on the cathode side, as necessary, by appropriately selecting them. The organic compound layer is mainly composed of an organic compound, but may contain inorganic atoms and inorganic compounds. For example, it may contain copper, lithium, magnesium, aluminum, iridium, platinum, molybdenum, zinc, and the like.

[0077] 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, instead of the dry process, a wet process can be used in which a layer is formed by dissolving the compound in an appropriate solvent and applying a known coating method (e.g., spin coating, dipping, casting, LB method, inkjet method, etc.). Here, when the 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 the layer is formed by a coating method, the layer can be formed by combining with a suitable binder resin.

[0078] 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. These binder resins may be used alone or in combination as homopolymers or copolymers, and may further include known additives such as plasticizers, antioxidants, and ultraviolet absorbers, if necessary.

[0079] [Protective layer] A protective layer may be provided on the second electrode. For example, by bonding glass provided with a moisture absorbent on the second electrode, it is possible to reduce the intrusion of water and the like into the organic compound layer and reduce the occurrence of display defects. In another embodiment, a passivation film such as silicon nitride may be provided on the second electrode to reduce the intrusion of water and the like into the organic compound layer. For example, after the second electrode is formed, it may be transported to another chamber without breaking the vacuum, and a silicon nitride film having a thickness of 2 μm may be formed by the CVD method to serve as a protective layer. A protective layer may be provided using an atomic deposition method (ALD method) after the film is formed by the CVD method. The material of the film formed by the ALD method is not limited, and may be silicon nitride, silicon oxide, aluminum oxide, etc. Silicon nitride may be further formed by the CVD method on the film formed by the ALD method. The film formed by the ALD method may have a smaller thickness than the film formed by the CVD method. Specifically, it may be 50% or less, or even 10% or less.

[0080] [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 another substrate, and the substrate on which the organic light-emitting element is provided may be bonded to the color filter. Alternatively, a color filter may be patterned on the protective layer described above using a photolithography technique. The color filter may be made of a polymer.

[0081] [Planarization layer] A planarization layer may be provided between the color filter and the protective layer. The planarization layer is provided for the purpose of reducing unevenness of the layer below. It may also be called a material resin layer without limiting the purpose. The planarization layer may be composed of an organic compound, and may be either a low molecular weight or a high molecular weight, but is preferably a high molecular weight. The planarization layer may be provided above and below the color filter, and may be made of the same or different materials.Specific examples of the materials include polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicone resin, and urea resin.

[0082] [Microlens] The organic light-emitting element or the light-emitting device having the organic light-emitting element may have an optical member such as a microlens on the light-emitting side. The microlens may be made of acrylic resin, epoxy resin, or the like. The microlens may be intended to increase the amount of light extracted from the organic light-emitting element or the light-emitting device and to control the direction of the extracted light. The microlens may have a hemispherical shape. When the microlens has a hemispherical shape, among the tangents to the hemisphere, there is a tangent that is parallel to the insulating layer, and the tangent and the hemisphere are the vertices of the microlens. The vertex of the microlens can be determined in the same manner in any cross-sectional view. That is, among the tangents to the semicircle of the microlens in the cross-sectional view, there is a tangent that is parallel to the insulating layer, and the tangent and the semicircle are the vertices of the microlens.

[0083] It is also possible to define the midpoint of the microlens. In the cross section of the microlens, a line segment is imaginary from a point where an arc shape ends to a point where another arc shape ends, and the midpoint of the line segment can be called the midpoint of the microlens. The cross section for determining the vertex and midpoint may be a cross section perpendicular to the insulating layer.

[0084] [Opposite 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 constituent material of the counter substrate may be the same as that of the aforementioned substrate. When the aforementioned substrate is a first substrate, the counter substrate may be a second substrate.

[0085] [Pixel circuit] The light-emitting device having the organic light-emitting element may have a pixel circuit connected to the organic light-emitting element. The pixel circuit may be an active matrix type that controls the emission of a plurality of organic light-emitting elements independently. The active matrix type circuit may be voltage programming or current programming. The driving circuit has a pixel circuit for each pixel. The pixel circuit may have an organic light-emitting element, a transistor that controls the emission luminance of the organic light-emitting element, a transistor that controls the emission timing, a capacitance that holds the gate voltage of the transistor that controls the emission luminance, and a transistor for connecting to GND without passing through the light-emitting element.

[0086] The light emitting device has a display region and a peripheral region arranged around the display region. The display region has a pixel circuit, and the peripheral region has a display control circuit. The mobility of a transistor constituting the pixel circuit may be smaller than the mobility of a transistor constituting the display control circuit. The slope of the current-voltage characteristic of the transistor constituting the pixel circuit may be smaller 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 an organic light emitting element.

[0087] [Pixels] A light emitting device having an organic light emitting element may have a plurality of pixels, each of which has sub-pixels that emit different colors, and each of the sub-pixels may have, for example, RGB light emitting colors. The pixel emits light in an area also called the pixel aperture. This area is the same as the first area. The pixel aperture may be 15 μm or less, or 5 μm or more. More specifically, it may be 11 μm, 9.5 μm, 7.4 μm, 6.4 μm, etc. The distance between the subpixels may be 10 μm or less, or more specifically, it may be 8 μm, 7.4 μm, 6.4 μm. The pixels may have a known arrangement in plan view. For example, they may have a stripe arrangement, a delta arrangement, a pentile arrangement, or a Bayer arrangement. The shape of the subpixels in plan view may be any known shape. For example, they may be a rectangle, a quadrangle such as a diamond, or a hexagon. Of course, if the shape is not an exact figure but is close to a rectangle, it is included in the rectangle. The shape of the subpixels and the pixel arrangement may be used in combination.

[0088] <Applications of organic light-emitting devices> The organic light-emitting device according to the present embodiment 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.

[0089] The display device may be an image information processing device having an image input unit that inputs image information from an area CCD, a linear CCD, a memory card, etc., an information processing unit that processes the input information, and displays the input image on a display unit. The display device may have a plurality of pixels, and at least one of the plurality of pixels may have the organic light-emitting element of this embodiment and a transistor connected to the organic light-emitting element. The display unit of the imaging device or inkjet printer may have a touch panel function. The driving method of the touch panel function may be an infrared type, a capacitance type, a resistive film type, or an electromagnetic induction type, and is not particularly limited. The display device may be used in the display unit of a multifunction printer.

[0090] Next, the display device according to the present embodiment will be described with reference to the drawings. FIG. 2(a) is an example of a pixel that is a component of the display device according to this embodiment. The pixel has sub-pixels 10. The sub-pixels are divided into 10R, 10G, and 10B according to their light emission. The emitted light color may be distinguished by the wavelength emitted from the light-emitting layer, or the light emitted from the sub-pixel may be selectively transmitted or color-converted by a color filter or the like. Each sub-pixel 10 has a reflective electrode that is a first electrode 2 on an interlayer insulating layer 1, an insulating layer 3 that covers the edge of the first electrode 2, an organic compound layer 4 that covers the first electrode 2 and the insulating layer 3, a transparent electrode that is a second electrode 5, a protective layer 6, and a color filter 7. 8 is an organic light-emitting element.

[0091] A transistor and a capacitor may be disposed below or inside the interlayer insulating layer 1. The transistor and the first electrode 2 may be electrically connected via a contact hole (not shown) or the like. The insulating layer 3 is also called a bank or a pixel separation film. It covers the ends of the first electrodes 2 and is disposed so as to surround the first electrodes 2. The portions where the insulating layer 3 is not disposed are in contact with the organic compound layer 4 and become light-emitting regions. The second electrode 5 may be a transparent electrode, a reflective electrode, or a semi-transparent electrode. The protective layer 6 reduces the penetration of moisture into the organic compound layer 4. The protective layer 6 is illustrated as being a single layer, but may be a multi-layer. Each layer may be an inorganic compound layer and an organic compound layer.

[0092] The color filters 7 are divided into 7R, 7G, and 7B according to their colors. The color filters 7 may be formed on a planarization layer (not shown). Also, a resin protective layer (not shown) may be provided on the color filters 7. Also, the color filters 7 may be formed on the protective layer 6. Alternatively, the color filters 7 may be provided on an opposing substrate such as a glass substrate and then bonded thereto.

[0093] FIG. 2(b) is a schematic cross-sectional view showing an example of a display device having an organic light-emitting element and a transistor connected to the organic light-emitting element. The organic light-emitting element 26 and a TFT (thin-film transistor) 18 as an example of the transistor are provided. A substrate 11 such as glass or silicon and an insulating layer 12 are provided on the upper part thereof. Active elements such as the TFT 18 are arranged on the insulating layer 12, and a gate electrode 13, a gate insulating film 14, and a semiconductor layer 15 of the active element are arranged. The TFT 18 is also composed of a drain electrode 16 and a source electrode 17. An insulating film 19 is provided on the upper part of the TFT 18. The anode 21 constituting the organic light-emitting element 26 and the source electrode 17 are connected via a contact hole 20 provided in the insulating film 19.

[0094] Note that the electrical connection method between the electrodes (anode 21, cathode 23) included in the organic light-emitting element 26 and the electrodes (source electrode 17, drain electrode 16) included in the TFT 18 is not limited to the mode shown in FIG. 2(b). That is, any one of the anode 21 or the cathode 23 and any one of the source electrode 17 or the drain electrode 16 of the TFT 18 may be electrically connected.

[0095] In the display device of FIG. 2(b), the organic compound layer 22 is illustrated as one layer, but the organic compound layer 22 may be a plurality of layers. A first protective layer 24 and a second protective layer 25 for reducing the deterioration of the organic light-emitting element 26 are provided on the cathode 23. Further, the transistor used in the display device of FIG. 2(b) is not limited to a transistor using a single-crystalline silicon wafer, and may be a thin-film transistor having an active layer on an insulating surface of a substrate. Examples of the active layer include non-single-crystalline silicon such as single-crystalline silicon, amorphous silicon, and microcrystalline silicon, and non-single-crystalline oxide semiconductors such as indium zinc oxide and indium gallium zinc oxide.

[0096] The transistors included in the display device of Fig. 2(b) may be formed in a substrate such as a Si substrate. Here, "formed in a substrate" means that the substrate itself such as a Si substrate is processed to produce the transistors. In other words, having a transistor in a substrate can be seen as the substrate and the transistor being integrally formed.

[0097] The organic light-emitting element 26 according to this embodiment has its light emission brightness controlled by a TFT, which is an example of a switching element, and by providing the organic light-emitting element 26 on multiple surfaces, an image can be displayed based on the respective light emission brightnesses. The switching element according to this embodiment is not limited to a TFT, and may be a transistor formed of low-temperature polysilicon or an active matrix driver formed on a substrate such as a Si substrate. On the substrate can also be referred to as within the substrate. Whether to provide a transistor within the substrate or to use a TFT is selected according to the size of the display unit. For example, if the size is about 0.5 inches, it is preferable to provide the organic light-emitting element on a Si substrate.

[0098] 3 is a schematic diagram showing an example of a display device according to this embodiment. The display device 1000 has 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. Flexible printed circuits FPC1002 and 1004 are connected to the touch panel 1003 and the display panel. A transistor is 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 if the display device is a portable device.

[0099] The display device according to the present embodiment may have color filters having red, green, and blue colors, and the red, green, and blue colors may be arranged in a delta arrangement in the color filters. 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 mobile phones such as smartphones, tablets, and head-mounted displays. The display device according to the present embodiment may be used as a display unit of an imaging device having an optical unit with a plurality of 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 may be a display unit disposed within a viewfinder. The imaging device may be a digital camera or a digital video camera.

[0100] 4(a) is a schematic diagram showing an example of an imaging device according to this embodiment. The imaging device 1100 may have a viewfinder 1101, a rear display 1102, an operation unit 1103, and a housing 1104. The viewfinder 1101 has 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 moving speed of the subject, the possibility that the subject will be blocked by an obstruction, and the like.

[0101] Since the timing suitable for imaging is short, it is better to display information as soon as possible. Therefore, the display device using the organic light-emitting element of this embodiment is used. This is because the organic light-emitting element has a fast response speed. The display device using the organic light-emitting element is more suitable for use than liquid crystal display devices, which require a high display speed.

[0102] The imaging device 1100 has an optical section (not shown). The optical section has a plurality of lenses, which form an image on an imaging element housed in a housing 1104. The focus of the plurality of lenses can be adjusted by adjusting their relative positions. This operation can also be performed automatically. The imaging device may be called a photoelectric conversion device. The photoelectric conversion device can include an imaging method that does not capture images sequentially, but detects the difference from the previous image, cuts out an image from an image that is always recorded, and the like.

[0103] FIG. 4(b) is a schematic diagram showing an example of an electronic device according to the present 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 1202 may be a biometric recognition unit that recognizes a fingerprint and releases a lock. An electronic device having a communication unit can also be called a communication device. The electronic device 1200 may further have a camera function by including a lens and an image sensor. An image captured by the camera function is displayed on the display unit 1201. Examples of the electronic device 1200 include a smartphone and a notebook computer.

[0104] FIG. 5 is a schematic diagram showing an example of a display device according to the present embodiment. FIG. 5(a) 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 organic light-emitting element according to the present embodiment is used in the display unit 1302. The display unit 1300 has the frame 1301 and a base 1303 that supports the display unit 1302. The base 1303 is not limited to the form shown in FIG. 5(a). The lower side of the frame 1301 may also serve as the base. 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.

[0105] FIG. 5(b) is a schematic diagram showing another example of the display device according to the present embodiment. The display device 1310 of 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 have the organic light-emitting element according to the present embodiment. The first display unit 1311 and the second display unit 1312 may be a single display unit without a joint. The first display unit 1311 and the second display unit 1312 can be separated at the bending point. The first display unit 1311 and the second display unit 1312 may display different images, or the first and second display units may display one image.

[0106] FIG. 6(a) is a schematic diagram showing an example of the lighting device according to the present embodiment. The lighting device 1400 may have a housing 1401, a light source 1402, a circuit board 1403, an optical filter 1404 that transmits light emitted by the light source 1402, and a light diffusion unit 1405. The light source 1402 has an organic light-emitting element according to the present embodiment. The optical filter 1404 may be a filter that improves the color rendering of the light source. The light diffusion unit 1405 can effectively diffuse the light of the light source, such as for lighting up, and deliver the light to a wide range. The optical filter 1404 and the light diffusion unit 1405 may be provided on the light emission side of the lighting. If necessary, a cover may be provided on the outermost part.

[0107] The lighting device is, for example, a device that illuminates a room. The lighting device may emit white light, neutral white light, or any other color from blue to red. It may have a dimming circuit that adjusts the light intensity. The lighting device may have the organic light-emitting element of this embodiment, and may further have a power supply circuit connected to the organic light-emitting element. The power supply circuit is a circuit that converts AC voltage into DC voltage. In addition, white has a color temperature of 4200K, and neutral white has a color temperature of 5000K. The lighting device may have a color filter. The lighting device according to the present embodiment may also include a heat dissipation section that dissipates heat from within the device to the outside, and examples of the heat dissipation section include metals with high specific heat, liquid silicone, and the like.

[0108] 6B 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 a lamp. The automobile 1500 has tail lamps 1501, and may be configured to turn on the tail lamps when braking or the like is performed. The tail lamp 1501 has an organic light-emitting element according to this embodiment. The tail lamp 1501 may have 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 is preferably made of polycarbonate or the like. Polycarbonate may be mixed with a furandicarboxylic acid derivative, an acrylonitrile derivative, or the like.

[0109] The automobile 1500 may have a body 1503 and a window 1502 attached thereto. The window 1502 may be a transparent display unless it is a window for checking the front and rear of the automobile. The transparent display has the organic light-emitting element according to this embodiment. In this case, the constituent materials of the electrodes and the like of the organic light-emitting element are made of transparent members.

[0110] The moving body according to the present embodiment may be a ship, an aircraft, a drone, or the like. The moving body may have a body and a lamp provided on the body. The lamp may emit light to indicate the position of the body. The lamp has the organic light-emitting element according to the present embodiment.

[0111] An application example of the display device of each of the above-mentioned embodiments will be described with reference to Fig. 7. The display device can be applied to a system that can be worn as a wearable device such as smart glasses, HMD, and smart contacts. An image capturing and display device used in such an application example has an image capturing device capable of photoelectrically converting visible light, and a display device capable of emitting visible light.

[0112] Fig. 7(a) is a schematic diagram showing an example of a wearable device according to an embodiment of the present invention. Using Fig. 7(a), glasses 1600 (smart glasses) according to one application example will be described. An imaging device 1602 such as a CMOS sensor or SPAD is provided on the front side of a lens 1601 of the glasses 1600. In addition, a display device according to each of the above-mentioned embodiments is provided on the back side of the lens 1601. The glasses 1600 further include a control device 1603. The control device 1603 functions as a power source that supplies power to the image capture device 1602 and the display device. The control device 1603 also controls the operations of the image capture device 1602 and the display device. The lens 1601 is formed with an optical system for focusing light on the image capture device 1602.

[0113] FIG. 7(b) is a schematic diagram showing another example of a wearable device according to an embodiment of the present invention. Using FIG. 7(b), glasses 1610 (smart glasses) according to one application example will be described. The glasses 1610 have a control device 1612, and the control device 1612 is equipped with an imaging device corresponding to the imaging device 1602 in FIG. 7(a) and a display device. The lens 1611 is formed with an imaging device in the control device 1612 and an optical system for projecting light emitted from the display device, and an image is projected onto the lens 1611. The control device 1612 functions as a power source that supplies power to the imaging device and the display device, and controls the operations of the imaging device and the display device.

[0114] The control device 1612 may have a gaze detection unit that detects the gaze of the wearer. Infrared rays may be used to detect the gaze. The infrared light emitting unit emits infrared light to the eyeball of the user gazing at the display image. The image capturing unit having a light receiving element detects the reflected light of the emitted infrared light from the eyeball to obtain an image of the eyeball. By providing a reduction means for reducing the light from the infrared light emitting unit to the display unit in a planar view, the deterioration of image quality is reduced. The gaze of the user to the display image is detected from the image of the eyeball obtained by capturing infrared light. Any known method can be applied to gaze detection using the image of the eyeball. As an example, a gaze detection method based on a Purkinje image due to reflection of irradiated light on the cornea can be used. More specifically, gaze detection processing based on a pupil-corneal reflex method is performed. Using the pupil-corneal reflex method, a gaze vector representing the direction (rotation angle) of the eyeball is calculated based on the image of the pupil and the Purkinje image included in the image of the eyeball, thereby detecting the gaze of the user.

[0115] A display device according to an embodiment of the present invention may have an imaging device having a light receiving element, and may control a display image of the display device based on the user's line of sight information from the imaging device. Specifically, the display device determines a first field of view area to which the user gazes and a second field of view area other than the first field of view area based on the line of sight information. The first field of view area and the second field of view area may be determined by a control device of the display device, or may be received from an external control device. In the display area of ​​the display device, the display resolution of the first field of view area may be controlled to be higher than the display resolution of the second field of view area. In other words, the resolution of the second field of view area may be lower than that of the first field of view area.

[0116] The display area includes a first display area and a second display area different from the first display area, and an area having a high priority is determined from the first display area and the second display area based on line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the display device, or may be received from an external control device. The resolution of the area having a high priority may be controlled to be higher than the resolution of areas other than the area having a high priority. In other words, the resolution of an area having a relatively low priority may be lowered.

[0117] In addition, AI may be used to determine the first field of view area and the area with high priority. The AI ​​may be a model configured to estimate the angle of the line of sight and the distance to an object at the end of the line of sight from the image of the eyeball, using the image of the eyeball and the direction in which the eyeball in the image was actually looking as teacher data. The AI ​​program may be included in the display device, the imaging device, or an external device. If included in the external device, it is transmitted to the display device via communication. When display control is performed based on visual recognition detection, the present invention is preferably applicable to smart glasses that further include an imaging device for capturing images of the outside world. The smart glasses can display captured outside information in real time.

[0118] FIG. 8(a) is a schematic diagram showing an example of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 40 is an electrophotographic image forming apparatus, and includes a photoconductor 27, an exposure light source 28, a charging unit 30, a developing unit 31, a transfer unit 32, a transport roller 33, and a fixing unit 35. Light 29 is irradiated from the exposure light source 28, and an electrostatic latent image is formed on the surface of the photoconductor 27. The exposure light source 28 includes an organic light-emitting element according to this embodiment. The developing unit 31 includes a toner, etc. The charging unit 30 charges the photoconductor 27. The transfer unit 32 transfers the developed image to a recording medium 34. The transport roller 33 transports the recording medium 34. The recording medium 34 is, for example, paper. The fixing unit 35 fixes the image formed on the recording medium 34.

[0119] 8(b) and 8(c) are diagrams showing the exposure light source 28, and are schematic diagrams showing a state in which a plurality of light-emitting units 36 are arranged on a long substrate. The arrow 37 is a direction parallel to the axis of the photoconductor, and represents the column direction in which the light-emitting units 36 having organic light-emitting elements are arranged. This column direction is the same as the axis direction about which the photoconductor 27 rotates. This direction can also be called the long axis direction of the photoconductor 27. FIG. 8(b) shows a form in which the light-emitting units 36 are arranged along the long axis direction of the photoconductor 27. FIG. 8(c) shows a form different from FIG. 8(b), in which the light-emitting units 36 are alternately arranged in the column direction in each of the first column and the second column. The first column and the second column are arranged at different positions in the row direction. In the first column, a plurality of light-emitting units 36 are arranged at intervals. In the second column, the light-emitting units 36 are arranged at positions corresponding to the intervals between the light-emitting units 36 in the first column. That is, a plurality of light-emitting units 36 are also arranged at intervals in the row direction. The arrangement in FIG. 8(c) can be rephrased as, for example, a grid arrangement, a houndstooth arrangement, or a checkerboard pattern.

[0120] As described above, by using a device using the organic light-emitting element according to this embodiment, it is possible to achieve a display with good image quality and stability even over a long period of time.

[0121] [Included configuration] The disclosure of this embodiment includes the following configuration. (Configuration 1) An organic light-emitting device having a first electrode, an organic compound layer, and a second electrode, The organic light-emitting device is characterized in that the organic compound layer has at least a layer containing a first compound represented by the following general formula [1] and a second compound represented by the following general formula [2]:

[0122] [ka] (In the general formulas [1] and [2], R1 to R7 are each independently selected from a hydrogen atom, a deuterium atom, a linear, branched or cyclic substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group, and Ar1 is a substituted or unsubstituted fused polycyclic group having three or more rings.)

[0123] (Configuration 2) 2. The organic light-emitting device according to configuration 1, wherein the layer containing the first compound and the second compound is a light-emitting layer. (Configuration 3) The organic light-emitting element according to configuration 2, characterized in that the light-emitting layer contains a light-emitting material, and the total amount of the first compound and the second compound contained in the light-emitting layer is 80% by weight or more and 99% by weight or less. (Configuration 4) The energy levels of the LUMOs of the first compound, the second compound, and the light-emitting material are designated as LUMO1, LUMO2, LUMO3, LUMO4, LUMO5, LUMO6, LUMO7, LUMO8, LUMO9, LUMO10, LUMO11, LUMO12, LUMO13, LUMO14, LUMO15, LUMO16, LUMO17, LUMO18, E The organic light-emitting device according to the configuration 2 or 3, wherein the following formula [A] is satisfied: |LUMO2|>|LUMO E |>|LUMO1| [A]

[0124] (Configuration 5) The organic light-emitting element according to any one of structures 1 to 4, characterized in that the content of the second compound is more than 0 and less than 0.2 mass%, with the total of the first compound and the second compound being 100 mass%.

[0125] (Configuration 6) The organic light-emitting device according to any one of structures 1 to 5, characterized in that the first compound is a compound represented by the following general formula [3], and the second compound is a compound represented by the following general formula [4]. [ka] (In the general formulas [3] and [4], R1, R2, and R4 to R 15are each independently selected from a hydrogen atom, a linear, branched or cyclic alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. (Configuration 7) 7. The organic light-emitting device according to configuration 6, wherein in the first compound and the second compound, R5 is a pyrenyl group or R6 is a fluorenyl group. (Configuration 8) 7. The organic light-emitting device according to configuration 6, wherein R6 in the first compound and the second compound is any one of a naphthyl group, a phenyl group, and a dibenzothiophenyl group.

[0126] (Configuration 9) 6. The organic light-emitting device according to any one of configurations 1 to 5, wherein in the first compound and the second compound, Ar1 is a fused polycyclic group other than pyrene. (Configuration 10) 10. The organic light-emitting device according to claim 9, wherein in the first compound and the second compound, Ar1 is a fluoranthene group. (Configuration 11) 10. The organic light-emitting device according to claim 9, wherein in the first compound and the second compound, Ar1 is an anthracene group.

[0127] (Configuration 12) 12. The organic light-emitting device according to any one of Structures 1 to 11, further comprising a second light-emitting layer disposed by stacking with the light-emitting layer as a first light-emitting layer, wherein the first light-emitting layer and the second light-emitting layer have emission colors different from each other.

[0128] (Configuration 13) 13. A display device comprising a plurality of pixels, at least one of which comprises an organic light-emitting element according to any one of structures 1 to 12 and a transistor connected to the organic light-emitting element. (Configuration 14) an optical unit having a plurality of lenses, an image sensor that receives light that has passed through the optical unit, and a display unit that displays an image captured by the image sensor; 13. A photoelectric conversion device, wherein the display section comprises the organic light-emitting element according to any one of the first to second aspects. (Configuration 15) 13. An electronic device comprising: a display unit having the organic light-emitting element according to any one of structures 1 to 12; a housing in which the display unit is provided; and a communication unit provided in the housing and configured to communicate with an external device. (Configuration 16) 13. A lighting device comprising: a light source having the organic light-emitting element according to any one of configurations 1 to 12; and a light diffusion section or an optical filter that transmits light emitted by the light source. (Configuration 17) 13. A moving body comprising: a lighting fixture having the organic light-emitting element according to any one of configurations 1 to 12; and a body on which the lighting fixture is provided. (Configuration 18) 13. An exposure light source for an electrophotographic image forming apparatus, comprising the organic light emitting device according to any one of claims 1 to 12. EXAMPLES

[0129] The present invention will be described below with reference to examples, although the present invention is not limited thereto.

[0130] <Adjustment of Composition> 9.988 g of compound A-1 represented by general formula [1] and 0.012 g of compound A-2 represented by general formula [2] were weighed out using a microbalance, and the weighed compounds were thoroughly mixed in a mortar. The resulting mixture was analyzed by high performance liquid chromatography (HPLC). As a result, it was confirmed that composition 1-1 containing 0.12 mass % of compound A-2 represented by general formula [2] was obtained.

[0131] In the same manner as above, compositions 1-2 to 1-5 were obtained by changing the mixing ratio of A-2 to A-1 as shown in Table 9. Furthermore, in the same manner as above, compositions containing different ratios of the assistant represented by general formula [2] were obtained by changing the mixing ratio of the assistant represented by general formula [2] to each host represented by general formula [1] shown in Table 9.

[0132] [Table 9]

[0133] (Example 1, Comparative Example 1) An ITO film was formed on a glass substrate and the desired patterning process was performed to form an ITO electrode (anode). At this time, the film thickness of the ITO electrode was set to 100 nm. The substrate on which the ITO electrode was formed was used as an ITO substrate. -4 Pa(1×10 -6 The organic compound layer and the electrode layer shown in Table 10 were successively deposited by vacuum deposition using resistance heating in a vacuum chamber at a pressure of 1000 MPa (torr) to prepare an organic light-emitting device. 2 The composition 1-1 in the light-emitting layer is a composition having the composition ratio shown in Table 9.

[0134] [Table 10]

[0135] The characteristics of the obtained organic light-emitting device were measured and evaluated, and blue light emission was obtained with a maximum current efficiency of 6.6 cd / A. Specifically, the current-voltage characteristics were measured using a microammeter 4140B manufactured by Hewlett-Packard, and the luminance was measured using a BM7 manufactured by Topcon.

[0136] Organic light-emitting devices were fabricated in the same manner as above, except that composition 1-1 was changed to compositions 1-0, 1-2 to 1-5 having different composition ratios as shown in Table 9. The current efficiency of the obtained organic light-emitting device was measured in the same manner as above. In addition, the current density was 200 mA / cm 2 The device durability was evaluated by measuring the time it took for the brightness to decrease to half its original brightness. The evaluation criteria were as follows. The results are shown in Table 11.

[0137] AAA: Brightness half-life is 1000 hours or more AA: Brightness halving time is between 500 and 1000 hours A: Brightness half-life is between 200 hours and 500 hours B: Luminance halving time is between 50 hours and 200 hours C: The brightness halving time is less than 50 hours

[0138] [Table 11]

[0139] As shown in Table 11, when the content of the second compound is 0.2 mass% or less, the element life is improved while maintaining the same current efficiency compared to an element containing 0 mass% of the second compound. On the other hand, when the content of the second compound exceeds 0.2 mass%, the durable life is further improved, but the current efficiency is reduced.

[0140] (Examples 2 to 10, Comparative Examples 2 to 10) An organic light-emitting device was produced in the same manner as in Example 1, except that the composition of the first compound and the second compound, and the light-emitting material in Example 1 were appropriately changed to the composition and light-emitting material shown in Table 12. The characteristics of the obtained device were measured and evaluated in the same manner as in Example 1. The measurement results are shown in Table 12. In Table 12, the content of the second compound is the content of the second compound in the composition (the first compound and the second compound), and the content of the light-emitting material is the content of the light-emitting material in the light-emitting layer.

[0141] [Table 12]

[0142] (Examples 11 to 16, Comparative Examples 11 to 16) A 40 nm thick Ti film was formed on a glass substrate by sputtering, and then patterned using photolithography to form an anode. Note that the electrode area of ​​the opposing electrode (metal electrode layer, cathode) was 3 mm2. 2 Next, the substrate with the cleaned electrodes and the material were attached to a vacuum deposition device, and the-4 Pa(1×10 -6 Torr), and then UV / ozone cleaning was performed. Then, each layer was formed in the layer configuration shown in Table 13 below, and finally, sealing was performed under a nitrogen atmosphere to prepare an organic light-emitting device of Example 11.

[0143] [Table 13]

[0144] The obtained element exhibited good white light emission. An organic light-emitting element was produced in the same manner as above, except that the structure of the organic compound layer was changed as shown in Table 14. The current efficiency of the obtained organic light-emitting element was measured in the same manner as above. In addition, when the current density was set to 200 mA / cm 2 The device durability was evaluated by measuring the time it took for the brightness to decrease by half. The evaluation criteria were as follows. The results are shown in Table 14.

[0145] AAA: Brightness half-life is 2000 hours or more AA: Brightness half-life is between 1500 and 2000 hours A: Brightness half-life is between 1000 and 1500 hours B: Brightness half-life is between 500 and 1000 hours C: The brightness halving time is less than 500 hours

[0146] [Table 14]

[0147] From the above evaluation, it was found that when the first compound represented by general formula [1] coexists with the second compound represented by general formula [2] at a low concentration in the light-emitting layer, the second compound exhibits an assist effect of trapping charges, reducing the probability of collisions between excitons and charges, and thereby improving the operating life of the element.

Claims

1. An organic light-emitting device having a first electrode, an organic compound layer, and a second electrode, The organic compound layer has a light-emitting layer containing at least a first compound represented by the following general formula [1], a second compound represented by the following general formula [2], and a light-emitting material, 【Chemical 1】 (In the general formulas [1] and [2], R 1 ~R 7 are each independently selected from a hydrogen atom, deuterium, a linear, branched, or cyclic substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group, and Ar1 is a substituted or unsubstituted fused polycyclic group having three or more rings. When the LUMO energy levels of the first compound, the second compound, and the light-emitting material are LUMO1, LUMO2, and LUMOE, respectively, the following formula [A] is satisfied: |LUMO2|>|LUMOE|>|LUMO1| [A] The organic light-emitting device, wherein the second compound has an oscillator strength of less than 0.

1.

2. An organic light-emitting element as described in Claim 1, characterized in that the total of the first compound and the second compound contained in the light-emitting layer is 80% by weight or more and 99% by weight or less.

3. 2. The organic light-emitting element according to claim 1, wherein the content of the second compound is more than 0 and less than 0.2% by mass, where the total of the first compound and the second compound is 100% by mass.

4. 2. The organic light-emitting device according to claim 1, wherein the first compound is a compound represented by the following general formula [3], and the second compound is a compound represented by the following general formula [4]: 【Chemistry 2】 (In the general formulas [3] and [4], R 1 , R 2 , and R 4 ~R 15 are each independently selected from a hydrogen atom, a linear, branched or cyclic alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group.

5. The first compound and the second compound are R 5 is a pyrenyl group or R 6 The organic light-emitting device according to claim 4, wherein is a fluorenyl group.

6. The first compound and the second compound are R 6 5. The organic light-emitting device according to claim 4, wherein is any one of a naphthyl group, a phenyl group, and a dibenzothiophenyl group.

7. The organic light-emitting element according to claim 1 , wherein Ar 1 in the first compound and the second compound is a fused polycyclic group other than pyrene.

8. The organic light-emitting element according to claim 7 , wherein Ar 1 in the first compound and the second compound is a fluoranthene group.

9. The organic light-emitting element according to claim 7 , wherein the Ar 1 in the first compound and the second compound is an anthracene group.

10. 2. The organic light-emitting element according to claim 1, further comprising a second light-emitting layer disposed by stacking the light-emitting layer as a first light-emitting layer, wherein the first light-emitting layer and the second light-emitting layer have different emission colors.

11. 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.

12. 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 .

13. 11. 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.

14. 11. 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 filter that transmits light emitted by the light source.

15. 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.

16. An exposure light source for an electrophotographic image forming apparatus, comprising the organic light-emitting element according to claim 1 .

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