Azine compound, organic electroluminescent device material containing the azine compound, and organic electroluminescent device

Abstract

To provide an azine compound for forming an organic electroluminescent element exhibiting high luminous efficiency and long life, a material for organic electroluminescent elements having the azine compound and an organic electroluminescent element.SOLUTION: An azine compound, of the following formula, a material for organic electroluminescent elements having the azine compound and an organic electroluminescent element. (Ar1, Ar2: phenyl, biphenyl, naphthyl. Ar3: (a) 1 to 3 ring C6 to C18 aromatic hydrocarbon, or (b) a C4 to C25 group having a C4 to C18 heteroaromatic group constituted of H, C, O and divalent S. L1: a divalent 6-membered ring group. X:C-H, C-CH3, N (1 or 2). n1:1, 2, 3. n2:0,1, 2.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an azine compound, a material for an organic electroluminescent device containing the azine compound, and an organic electroluminescent device. [Background technology]

[0002] Organic electroluminescent devices have begun to be put to practical use, primarily for small mobile devices. However, further expansion of their applications requires improved performance, and materials with low driving voltage, high luminous efficiency, and long life are required. Therefore, materials for organic electroluminescent devices are required to have low crystallization temperatures and melting points.

[0003] Patent Documents 1 to 3 disclose azine compounds that are materials for organic electroluminescent devices that are highly efficient and can reduce the driving voltage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2007 / 023840 [Patent Document 2] Japanese Patent Application Publication No. 2019-99513 [Patent Document 3] Japanese Patent Application Publication No. 2019-147791 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a strong demand from the market for expanding the applications and the environments in which the devices can be used. However, the azine compounds disclosed in Patent Documents 1 to 3 do not fully satisfy the three characteristics of driving voltage, luminous efficiency, and life characteristics, and there is a demand for compounds that achieve the above three characteristics at an even higher level.

[0006] Therefore, one aspect of the present invention aims to provide an azine compound having a low crystallization temperature and melting point, which can form an organic electroluminescent device having excellent driving voltage characteristics and life characteristics, and a material for an organic electroluminescent device containing the azine compound.

[0007] Another object of the present invention is to provide an organic electroluminescent device that exhibits high luminous efficiency and can be used in a variety of applications or in a variety of environments. [Means for solving the problem]

[0008] The objects of each aspect of the present invention have been achieved as follows. 1) An azine compound represented by the following formula (1): Formula (1) [ka] During the ceremony, Ar 1 , Ar 2 independently represent a phenyl group, a biphenyl group, or a naphthyl group. Ar 3 represents a group having 4 to 25 carbon atoms and having a group selected from the following (a) and (b): (a) an aromatic hydrocarbon group having 6 to 18 carbon atoms and 1 to 3 rings (b) a heteroaromatic group having 4 to 18 carbon atoms and composed of atoms selected from the group consisting of H, C, O, and divalent S; L 1 represents a divalent 6-membered ring linking group. Each X independently represents CH, C-CH3, or N. 1 The number N is 1 or 2. n 1 represents an integer of 1 to 3. n 2 represents an integer of 0 to 2. 2) A material for organic electroluminescent devices, comprising the azine compound described in 1) above. 3) An organic electroluminescent device comprising the azine compound described in 1) above. [Effects of the Invention]

[0009] According to one aspect of the present invention, it is possible to provide an azine compound having a low crystallization temperature and melting point, which can form an organic electroluminescent device that exhibits excellent driving voltage characteristics and life characteristics, and a material for an organic electroluminescent device containing the azine compound.

[0010] According to another aspect of the present invention, an organic electroluminescent device that exhibits high luminous efficiency and can be used for various applications can be provided. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view showing an example of a layered structure of an organic electroluminescence element according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing another example of a laminated structure of an organic electroluminescence element according to one embodiment of the present invention (structure of element example 1). DETAILED DESCRIPTION OF THE INVENTION

[0012] The azine compound according to one embodiment of the present invention will be described in detail below. <Azine compounds>

[0013] An azine compound according to one embodiment of the present invention is an azine compound represented by formula (1). Formula (1) [ka] During the ceremony, Ar 1 , Ar 2 independently represent a phenyl group, a biphenyl group, or a naphthyl group. Ar 3 represents a group having 4 to 25 carbon atoms and having a group selected from the following (a) and (b): (a) an aromatic hydrocarbon group having 6 to 18 carbon atoms and 1 to 3 rings (b) a heteroaromatic group having 4 to 18 carbon atoms and composed of atoms selected from the group consisting of H, C, O, and divalent S; L 1 represents a divalent 6-membered ring linking group. Each X independently represents CH, C-CH3, or N. 1 The number N is 1 or 2. n 1 represents an integer of 1 to 3. n 2 represents an integer of 0 to 2.

[0014] Hereinafter, the azine compound represented by formula (1) may be referred to as azine compound (1).

[0015] The definitions of the substituents in the azine compound (1) and preferred examples thereof are as follows: [Ar 1 and Ar 2 About

[0016] Ar 1 and Ar 2 each independently represents a phenyl group, a biphenyl group, or a naphthyl group. 1 and Ar 2 may each independently be substituted with one or more groups selected from a fluorine atom, a methyl group, and a phenyl group. [Ar 3 About

[0017] Ar 3 represents a group having 4 to 25 carbon atoms and having a group selected from the following (a) and (b): (a) an aromatic hydrocarbon group having 6 to 18 carbon atoms and 1 to 3 rings (b) a heteroaromatic group having 4 to 18 carbon atoms and composed of atoms selected from the group consisting of H, C, O, and divalent S;

[0018] Ar 3 Preferably, the number of carbon atoms is 6 to 25.

[0019] Ar3 More preferably, represents a group selected from the following (a') to (c'): (a') an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms and having 1 to 3 rings (b') an unsubstituted heteroaromatic group having 4 to 18 carbon atoms and composed of atoms selected from the group consisting of H, C, O, and divalent S; (c') (a') or (b') is a group substituted with one or more groups selected from the group consisting of a methyl group and a phenyl group.

[0020] Ar 3 is preferably a phenyl group, a naphthyl group, a fluorenyl group, an anthranyl group, a phenanthrenyl group, a dibenzofuranyl group or a dibenzothiophenyl group. [L 1 About

[0021] L 1 represents a divalent 6-membered ring linking group. Each of the four Xs independently represents -CH, C-CH3, or N. 1 The number of N is 1 or 2. When N is 2, it is preferable that the two Ns are not adjacent to each other. 1 It is preferable that the number N is 1.

[0022] L 1 Examples of the alkyl group include a 1,4-phenylene group, a 2,5-pyridylene group, a 3,6-pyridylene group, a 2,5-pyrazylene group, a 2,5-pyrimidylene group, and a 2,5-pyridazylene group. [n 1 and n 2 About

[0023] n 1 represents an integer of 1 to 3. 1 is preferably 1 or 2. n 2 represents an integer of 0 to 2. 2 is preferably 0 or 1. [Specific examples of azine compound (1)]

[0024] Specific examples of the azine compound (1) are shown below, but the present invention is not limited to these.

[0025] [ka]

[0026] [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] [ka]

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] [ka]

[0035] The azine compound (1) according to one embodiment of the present invention can be produced by appropriately combining known reactions (for example, Suzuki-Miyaura cross-coupling reaction, etc.). <Materials for organic electroluminescent devices>

[0036] Azine compound (1) is useful as a material for organic electroluminescent devices. Azine compound (1) can be used, for example, as an electron transport material for organic electroluminescent devices. A material for organic electroluminescent devices containing azine compound (1) exhibits high luminous efficiency and long lifetime characteristics, and can be used to prepare organic electroluminescent devices that can be used for various purposes or in various environments. <Organic electroluminescent device>

[0037] An organic electroluminescent device containing the azine compound (1) (hereinafter, sometimes simply referred to as an organic electroluminescent device) will be described below.

[0038] The organic electroluminescent device according to one aspect of the present invention contains an azine compound (1).

[0039] The configuration of the organic electroluminescent device is not particularly limited, but examples thereof include the following configurations (i) to (v). (i): Anode / Emitting layer / Cathode (ii): Anode / hole transport layer / light-emitting layer / cathode (iii): Anode / Emitting layer / Electron transport layer / Cathode (iv): Anode / hole transport layer / light-emitting layer / electron transport layer / cathode (v): Anode / hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer / cathode

[0040] The azine compound (1) may be contained in any of the above layers. However, in terms of excellent light-emitting properties of the organic electroluminescent device, it is preferred that the azine compound (1) be contained in one or more layers selected from the group consisting of the light-emitting layer and the layer between the light-emitting layer and the cathode.

[0041] Therefore, in the case of the above structures (i) to (v), the azine compound (1) is preferably contained in one or more layers selected from the group consisting of the light-emitting layer, the electron-transporting layer, and the electron-injecting layer.

[0042] Hereinafter, an organic electroluminescent device according to one aspect of the present invention will be described in more detail with reference to FIG. 1, taking the above configuration (v) as an example.

[0043] 1 has a so-called bottom-emission type element configuration, the organic electroluminescent element according to one embodiment of the present invention is not limited to the bottom-emission type element configuration. That is, the organic electroluminescent element according to one embodiment of the present invention may have another known element configuration, such as a top-emission type.

[0044] FIG. 1 is a schematic cross-sectional view showing an example of a layer structure of an organic electroluminescent device containing an azine compound according to one embodiment of the present invention.

[0045] The organic electroluminescent device 100 includes, in this order, a substrate 1, an anode 2, a hole injection layer 3, a hole transport layer 4, an emitting layer 5, an electron transport layer 6, an electron injection layer 7, and a cathode 8. However, some of these layers may be omitted, or other layers may be added. For example, a hole blocking layer may be provided between the emitting layer 5 and the electron transport layer 6, or the hole injection layer 3 may be omitted and the hole transport layer 4 may be provided directly on the anode 2.

[0046] Alternatively, a single layer having the functions of multiple layers, such as an electron injection / transport layer having the functions of both an electron injection layer and an electron transport layer, may be provided instead of the multiple layers.Furthermore, for example, the single-layer hole transport layer 4 and the single-layer electron transport layer 6 may each be composed of multiple layers. <<Layer Containing Azine Compound (1)>>

[0047] 1, the organic electroluminescent device 100 contains an azine compound (1) in one or more layers selected from the group consisting of the light-emitting layer 5, the electron transport layer 6, and the electron injection layer 7. In particular, it is preferable that the electron transport layer 6 contains the azine compound (1). The azine compound (1) may be contained in multiple layers of the organic electroluminescent device.

[0048] The organic electroluminescent device 100 in which the electron transport layer 6 contains the azine compound (1) will be described below. [Board 1]

[0049] The substrate 1 is not particularly limited, and examples thereof include a glass plate, a quartz plate, and a plastic plate.

[0050] Examples of the substrate 1 include a glass plate, a quartz plate, a plastic plate, and a plastic film. Among these, a glass plate, a quartz plate, and a light-transmitting plastic film are preferred.

[0051] Examples of light-transmitting plastic films include films made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), cellulose acetate propionate (CAP), etc.

[0052] In the case of a configuration in which light is extracted from the substrate 1 side, the substrate 1 is transparent to the wavelength of light. [Anode 2]

[0053] An anode 2 is provided on the substrate 1 (on the hole injection layer 3 side).

[0054] Examples of anode materials include metals, alloys, electrically conductive compounds, and mixtures thereof, each having a large work function (e.g., 4 eV or more). Specific examples of anode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO, and ZnO.

[0055] In the case of an organic electroluminescent device configured so that light is extracted through the anode, the anode is formed from a conductive transparent material that is transparent or substantially transparent to the light emitted. [Hole injection layer 3, hole transport layer 4]

[0056] Between the anode 2 and the light-emitting layer 5, a hole injection layer 3 and a hole transport layer 4 are provided in this order from the anode 2 side.

[0057] The hole injection layer and the hole transport layer have the function of transporting holes injected from the anode to the light-emitting layer. By interposing these hole injection layer and hole transport layer between the anode and the light-emitting layer, a large number of holes can be injected into the light-emitting layer with a lower electric field.

[0058] The hole injection layer and the hole transport layer also function as electron barrier layers. That is, electrons injected from the cathode and transported from the electron injection layer and / or the electron transport layer to the light-emitting layer are prevented from leaking to the hole injection layer and / or the hole transport layer due to the electron barrier present at the interface between the light-emitting layer and the hole injection layer and / or the hole transport layer. As a result, the electrons accumulate at the interface within the light-emitting layer, resulting in effects such as improved light-emitting efficiency and providing an organic electroluminescent device with excellent light-emitting performance.

[0059] The material for the hole injection layer and the hole transport layer has at least one of hole injection property, hole transport property, and electron barrier property, and may be either organic or inorganic.

[0060] Specific examples of materials for the hole injection layer and the hole transport layer include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based copolymers, conductive polymer oligomers (particularly thiophene oligomers), porphyrin compounds, aromatic tertiary amine compounds, and styrylamine compounds.

[0061] Among these, porphyrin compounds, aromatic tertiary amine compounds, and styrylamine compounds are preferred in terms of good performance of the organic electroluminescent device, and aromatic tertiary amine compounds are particularly preferred.

[0062] Specific examples of the aromatic tertiary amine compound and the styrylamine compound include N,N,N',N'-tetraphenyl-4,4'-diaminophenyl, N,N'-diphenyl-N,N'-bis(m-tolyl)-[1,1'-biphenyl]-4,4'-diamine (TPD), 2,2-bis(4-di-p-tolylaminophenyl)propane, 1,1-bis(4-di-p-tolylaminophenyl)cyclohexane, N,N,N',N'-tetra-p-tolyl-4,4'-diaminobiphenyl, 1,1-bis(4-di-p-tolylaminophenyl)-4-phenylcyclohexane, bis(4-dimethylamino-2-methylphenyl)phenylmethane, bis(4-di-p-tolylaminophenyl)phenylmethane, N,N'-diphenyl-N,N'- Examples include di(4-methoxyphenyl)-4,4'-diaminobiphenyl, N,N,N',N'-tetraphenyl-4,4'-diaminodiphenyl ether, 4,4'-bis(diphenylamino)quadriphenyl, N,N,N-tri(p-tolyl)amine, 4-(di-p-tolylamino)-4'-[4-(di-p-tolylamino)styryl]stilbene, 4-N,N-diphenylamino-(2-diphenylvinyl)benzene, 3-methoxy-4'-N,N-diphenylaminostilbenzene, N-phenylcarbazole, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPD), and 4,4',4''-tris[N-(m-tolyl)-N-phenylamino]triphenylamine (MTDATA).

[0063] Furthermore, inorganic compounds such as p-type Si and p-type SiC can also be given as examples of materials for the hole injection layer and the hole transport layer.

[0064] The hole injection layer and the hole transport layer may have a single structure made of one or more materials, or may have a laminate structure made of multiple layers of the same or different compositions. [Emitting layer 5]

[0065] The light-emitting layer 5 is provided between the hole transport layer 4 and the electron transport layer 6 .

[0066] Materials for the light-emitting layer include phosphorescent materials, fluorescent materials, and thermally activated delayed fluorescent materials. In the light-emitting layer, electron-hole pairs recombine, resulting in light emission.

[0067] The light-emitting layer may consist of a single small molecule or single polymer material, but more commonly consists of a host material doped with a guest compound. Emission comes primarily from the dopant and can be of any color.

[0068] Examples of the host material include compounds having a biphenylyl group, a fluorenyl group, a triphenylsilyl group, a carbazole group, a pyrenyl group, and an anthryl group. More specific examples include DPVBi (4,4'-bis(2,2-diphenylvinyl)-1,1'-biphenyl), BCzVBi (4,4'-bis(9-ethyl-3-carbazovinylene)1,1'-biphenyl), TBADN (2-tert-butyl-9,10-di(2-naphthyl)anthracene), ADN (9,10-di(2-naphthyl)anthracene), CBP (4,4'-bis(carbazol-9-yl)biphenyl), CDBP (4,4'-bis(carbazol-9-yl)-2,2'-dimethylbiphenyl), 2-(9-phenylcarbazol-3-yl)-9-[4-(4-phenylphenylquinazolin-2-yl)carbazole, 9,10-bis(biphenyl)anthracene, and the like.

[0069] Examples of fluorescent dopants include anthracene, pyrene, tetracene, xanthene, perylene, rubrene, coumarin, rhodamine, quinacridone, dicyanomethylenepyran compounds, thiopyran compounds, polymethine compounds, pyrylium, thiapyrylium compounds, fluorene derivatives, periflanthene derivatives, indenoperylene derivatives, bis(azinyl)amine boron compounds, bis(azinyl)methane compounds, carbostyril compounds, boron compounds, cyclic amine compounds, etc. The fluorescent dopant may be a combination of two or more selected from these.

[0070] Examples of phosphorescent dopants include organometallic complexes of transition metals such as iridium, platinum, palladium, and osmium.

[0071] Specific examples of fluorescent dopants and phosphorescent dopants include Alq3 (tris(8-hydroxyquinoline)aluminum), DPAVBi (4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl), perylene, bis[2-(4-n-hexylphenyl)quinoline](acetylacetonate)iridium(III), Ir(PPy)3 (tris(2-phenylpyridine)iridium(III)), and FIrPic (bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III))).

[0072] Furthermore, the light-emitting material is not limited to being contained only in the light-emitting layer. For example, the light-emitting material may be contained in a layer adjacent to the light-emitting layer (hole transport layer 4 or electron transport layer 6). This can further increase the luminous efficiency of the organic electroluminescent device.

[0073] The light-emitting layer may have a single layer structure made of one or more materials, or may have a laminate structure made of multiple layers of the same or different compositions. [Electron transport layer 6]

[0074] Between the light-emitting layer 5 and the electron injection layer 7, an electron transport layer 6 is provided.

[0075] The electron transport layer has a function of transporting electrons injected from the cathode to the light-emitting layer. By interposing the electron transport layer between the cathode and the light-emitting layer, electrons are injected into the light-emitting layer at a lower electric field.

[0076] As described above, the electron transport layer preferably contains the azine compound (1). In addition to the azine compound (1), the electron transport layer may further contain one or more types selected from conventionally known electron transport materials.

[0077] When the azine compound (1) is not contained in the electron transport layer but in another layer, one or more electron transport materials selected from conventionally known electron transport materials can be used as the electron transport material constituting the electron transport layer.

[0078] Conventionally known electron transporting materials include alkali metal complexes, alkaline earth metal complexes, earth metal complexes, etc. Examples of alkali metal complexes, alkaline earth metal complexes, and earth metal complexes include 8-hydroxyquinolinatolithium (Liq), bis(8-hydroxyquinolinato)zinc, bis(8-hydroxyquinolinato)copper, bis(8-hydroxyquinolinato)manganese, tris(8-hydroxyquinolinato)aluminum, tris(2-methyl-8-hydroxyquinolinato)aluminum, and tris(8-hydroxyquinolinato). Examples of suitable gallium compounds include gallium, bis(10-hydroxybenzo[h]quinolinato)beryllium, bis(10-hydroxybenzo[h]quinolinato)zinc, bis(2-methyl-8-quinolinato)chlorogallium, bis(2-methyl-8-quinolinato)(o-cresolate)gallium, bis(2-methyl-8-quinolinato)-1-naphtholatealuminum, and bis(2-methyl-8-quinolinato)-2-naphtholategallium.

[0079] The electron transport layer may have a single layer structure made of one or more materials, or may have a laminate structure made of multiple layers of the same or different compositions.

[0080] In the organic electroluminescent device according to one aspect of the present invention, an electron injection layer may be provided for the purpose of improving electron injection properties and improving device characteristics (e.g., luminous efficiency, low-voltage driving, or high durability). [Electron injection layer 7]

[0081] An electron injection layer 7 is provided between the electron transport layer 6 and the cathode 8. The electron injection layer has the function of transporting electrons injected from the cathode to the light-emitting layer. By interposing the electron injection layer between the cathode and the light-emitting layer, electrons are injected into the light-emitting layer at a lower electric field.

[0082] Examples of materials for the electron injection layer include organic compounds such as fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxazole, oxadiazole, triazole, imidazole, perylene tetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane, and anthrone.

[0083] Further, examples of materials for the electron injection layer include inorganic compounds such as various oxides, fluorides, nitrides, and oxynitrides of SiO, AlO, SiN, SiON, AlON, GeO, LiO, LiON, TiO, TiON, TaO, TaON, TaN, LiF, C, and Yb. [Cathode 8]

[0084] A cathode 8 is provided on the electron injection layer 7. In the case of an organic electroluminescence element configured so that only light emitted through the anode is extracted, the cathode can be made of any conductive material.

[0085] Examples of materials for the cathode include metals with a low work function (hereinafter also referred to as electron-injecting metals), alloys, electrically conductive compounds, and mixtures thereof. Here, the metals with a low work function are, for example, metals with a work function of 4 eV or less.

[0086] Specific examples of cathode materials include sodium, sodium-potassium alloys, magnesium, lithium, magnesium / copper mixtures, magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al2O3) mixtures, indium, lithium / aluminum mixtures, and rare earth metals.

[0087] Among these, from the viewpoints of electron injection properties and durability against oxidation, etc., mixtures of an electron-injecting metal and a second metal that has a larger and more stable work function than the electron-injecting metal, such as magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al2O3) mixtures, and lithium / aluminum mixtures, are preferred. [How each layer is formed]

[0088] Each layer except for the electrodes (anode and cathode) described above can be formed into a thin film by a known method such as vacuum deposition, spin coating, casting, LB (Langmuir-Blodgett) method, etc. The material for each layer may be used alone or, if necessary, together with a material such as a binder resin or a solvent.

[0089] There are no particular limitations on the thickness of each layer thus formed, and it can be selected appropriately depending on the situation, but it is usually in the range of 5 nm to 5 μm.

[0090] The anode and cathode can be formed by forming a thin film of an electrode material by a method such as vapor deposition, sputtering, etc. A pattern may be formed through a mask of a desired shape during vapor deposition or sputtering, or a pattern of a desired shape may be formed by photolithography after forming a thin film by vapor deposition, sputtering, etc.

[0091] The thickness of the anode and cathode is preferably 1 μm or less, and more preferably 10 nm or more and 200 nm or less.

[0092] The layer containing the azine compound (1) may be formed in combination with the above-mentioned conventionally known electron transporting material. For example, the azine compound (1) and the conventionally known electron transporting material may be co-deposited, or a layer of the conventionally known electron transporting material may be laminated on the layer of the azine compound (1).

[0093] The organic electroluminescent device may be used as a type of lamp for illumination or exposure light source, or may be used as a projection device that projects an image onto a screen or the like, or as a display device (display) that displays still images or moving images directly.

[0094] When organic electroluminescent elements are used as display devices for playing moving images, the driving method may be a passive matrix method or an active matrix method. In addition, by using two or more types of organic electroluminescent elements having different emission colors, it is possible to produce a full-color display device.

[0095] The azine compound (1) can provide an organic electroluminescent device having significantly superior luminous efficiency and long life characteristics when used as an electron transport layer compared with conventionally known azine compounds. Furthermore, the azine compound (1) has a linear three-dimensional skeleton, which results in high amorphousness and high film stability.

[0096] Therefore, it is expected that the driving stability and luminous efficiency of the organic electroluminescent device will be improved. Furthermore, due to its characteristic skeleton, the azine compound (1) has high chemical stability and can contribute to the long life of the organic electroluminescent device.

[0097] Azine compound (1) can be used as an electron transport layer in an organic electroluminescent device to provide an azine compound that can achieve low-voltage operation, high efficiency, and long life of the device at a high level. Furthermore, an organic electroluminescent device using azine compound (1) can be provided that can achieve low-voltage operation, high efficiency, and long life. [Example]

[0098] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited to these examples. [ 1 H-NMR measurement]

[0099] 1 For the H-NMR measurement, Gemini200 (Varian) was used. 1 H-NMR was measured using deuterated chloroform (CDCl3) as the measurement solvent and tetramethylsilane (TMS) as the internal standard. Commercially available reagents were used. [DSC measurement (glass transition temperature, crystallization temperature, melting point)]

[0100] The glass transition temperature, crystallization temperature, and melting point were measured using a DSC7020 (product name, manufactured by Hitachi High-Tech Science Corporation).

[0101] The DSC measurement conditions are as follows. The measurement was carried out in a nitrogen atmosphere (flow rate 50 ml / min). First cooling was performed, followed by second heating. The glass transition temperature, crystallization temperature, and melting point during second heating were taken as the glass transition temperature, crystallization temperature, and melting point of the sample, respectively. Sample amount: 5 to 10 mg Measurement conditions: <Fast Heating> Heating rate: 15℃ / min Measurement temperature range: 30℃~360℃ <First cooling> Rapid cooling with dry ice <Second heating> Heating rate: 5℃ / min Measurement temperature range: 30℃~360℃ [Emission characteristics measurement]

[0102] The light-emitting characteristics of the organic electroluminescent device were evaluated by applying a direct current to the fabricated device in a 25° C. environment using a luminance meter BM-9 (product name, manufactured by Topcon Technohouse Corporation). (Synthesis Example 1: Synthesis of A-67)

[0103] [ka]

[0104] Under an argon atmosphere, 2-[4'-{(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1,1'-biphenyl-4-yl}]-4,6-diphenyl-1,3,5-triazine (6.0 g, 11.7 mmol), 5-chloro-2-(1-naphthyl)pyridine (3.37 g, 14.1 mmol), palladium acetate (105 mg, 0.939 mmol), and 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (447 mg, 0.469 mmol; X-Phos) were dissolved in tetrahydrofuran (120 mL). To this solution was added 2 M aqueous potassium phosphate solution (17.6 mL, 35.2 mmol) and stirred at 75 °C for 15 h. After cooling to room temperature, the precipitated solid was collected by filtration. The resulting solid was washed with water (100 mL) and methanol (100 mL). This solid was suspended in toluene (500 mL), stirred at 100°C, and then allowed to cool. The precipitated solid was filtered and washed with toluene (40 mL) and methanol (30 mL) to obtain the target white solid, 4,6-diphenyl-2-[4'-{2-(1-naphthyl)pyridin-5-yl}-1,1'-biphenyl-4-yl]-1,3,5-triazine (Compound A-67) (yield: 5.38 g, 78%).

[0105] 1 H-NMR(CDCl3)δ(ppm):9.14(d,J=2.2Hz,1H),8.92(d,J=8.6Hz,2H),8.84(d,J=8.1Hz,4H),8.22(t,J=3.9Hz,1H),8.14(dd,J=8.2 Hz,2.3Hz,1H),7.94(d,J=8.2Hz,2H),7.93-7.86(m,6H),7.73(dd,J=14.5Hz,8.9Hz,2H),7.67-7.60(m,7H),7.54(t,J=5.8Hz,2H)

[0106] The structure of compound A-67 is: 1 The glass transition temperature was not determined because no clear peak was observed. (Synthesis Example 2: Synthesis of A-70)

[0107] [ka]

[0108] The same experimental procedure as in Synthesis Example 1 was carried out, except that 5-chloro-2-(1-naphthyl)pyridine was replaced with 5-chloro-2-(phenanthren-9-yl)pyridine, to obtain the target 4,6-diphenyl-2-[4'-{2-(phenanthren-9-yl)pyridin-5-yl}-1,1'-biphenyl-4-yl]-1,3,5-triazine (A-70) as a white solid (yield: 4.4 g, 53%).

[0109] 1 H-NMR(CDCl3)δ(ppm):7.42-7.50(m,8H),7.55(t,J=7.8Hz,2H),7.62(d,J=8.1Hz,1H),7.68-7.75(m,6H),7.78(s,1H),7.80(d,J=8.1Hz,1H) ,7.98(dd,J=2.4Hz,8.1Hz,1H),8.05(d,J=8.3Hz,1H),8.59(d,J=8.3Hz,1H),8.64-8.67(m,5H),8.74(d,J=8.6Hz,2H),8.98(d,J=2.4Hz,1H)

[0110] The structure of compound A-70 is: 1 The glass transition temperature was determined to be 119°C by H-NMR. (Synthesis Example 3: Synthesis of A-91)

[0111] [ka]

[0112] Under an argon atmosphere, 2-[4-{(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl}]-4,6-diphenyl-1,3,5-triazine (1.31 g, 3.0 mmol), 1-chloro-4-{4-(naphthalen-1-yl)pyrimidin-2-yl}phenyl (1.14 g, 3.6 mmol), palladium acetate (20.4 mg, 0.09 mmol), and X-Phos (85.8 mg, 0.18 mmol) were dissolved in tetrahydrofuran (15 mL). To this solution, 2 M aqueous potassium carbonate (18 mL, 36 mmol) was added and stirred at 75 °C for 18 hours. After cooling to room temperature, the precipitated solid was filtered off. The resulting solid was washed with water (50 mL) and ethanol (50 mL). The resulting solid was dissolved in toluene (50 mL). Activated carbon was added to the solution, and the mixture was stirred. The mixture was filtered through Celite, and the filtrate was concentrated under reduced pressure. The concentrated solution was dried to obtain the target compound, 4,6-diphenyl-2-[4'-{5-(naphthalen-1-yl)pyrimidin-2-yl}-1,1'-biphenyl-4-yl]1,3,5-triazine (A-91), as a white solid (yield: 1.38 g, 78%).

[0113] 1H-NMR(CDCl3)δ(ppm):7.46-7.67(m,12H),7.92(t,J=8.2Hz,2H),7.99(d,J=7.6,2H) ,8.69(d,J=8.5Hz,2H),8.82(dd,J=7.8,4Hz,4H),8.90(d,J=8.5Hz,2H),9.01(s,2H).

[0114] The structure of compound A-91 is: 1 The glass transition temperature was determined to be 102°C by H-NMR. (Synthesis Example 4: Synthesis of A-148)

[0115] [ka]

[0116] Under an argon atmosphere, 2,4-bis[(1,1'-biphenyl)-4-yl]-6-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl]-1,3,5-triazine (5.05 g, 8.6 mmol) (3.40 g, 5.8 mmol), 3-chloro-2-methyl-6-phenylpyridine (1.41 g, 6.9 mmol), palladium acetate (26.0 mg, 0.12 mmol), and X-Phos (110.0 mg, 0.23 mmol) were dissolved in tetrahydrofuran (58 mL). To this solution, 2 M aqueous potassium carbonate (8.7 mL, 17 mmol) was added and stirred at 75 °C for 22 hours. After cooling to room temperature, the precipitated solid was filtered off. The resulting solid was washed with water (100 mL) and ethanol (100 mL). The resulting solid was dissolved in 400 mL of toluene. Activated carbon was added to the solution, which was then stirred. The mixture was then filtered through Celite, and the filtrate was concentrated under reduced pressure. The concentrated solution was dried to obtain the target 4,6-bis[(1,1'-biphenyl)-4-yl]-2-[(2-methyl-6-phenylpyridin-3-yl)-phenyl-4-yl]-1,3,5-triazine (A-148) as a white solid (yield: 2.38 g, 65%).

[0117] 1H-NMR(CDCl3)δ(ppm):7.34-7.40(m,6H),6.57-6.53(m,2H),6.34-6.28(m,4H),6.25-5.88(m,17H),1.11(s,3H).

[0118] The structure of compound A-148 is: 1 The glass transition temperature was determined to be 107°C by H-NMR.

[0119] The crystallization temperature and melting point of the azine compound (1) prepared above are shown below.

[0120] [Table 1]

[0121] It is understood that the azine compound according to one embodiment of the present invention has a lower crystallization temperature and melting point than the following ETL-1 described in Patent Document 1.

[0122] [ka] <Fabrication of organic electric field element>

[0123] Next, the obtained compound was used to carry out device evaluation. <Element Example 1 (see Figure 2)> (Preparation of the substrate 101 and the anode 102)

[0124] A glass substrate with an indium-tin oxide (ITO) transparent electrode, patterned with a 2 mm wide stripe of ITO (110 nm thick), was prepared as a substrate with an anode on its surface. The substrate was then cleaned with isopropyl alcohol and then subjected to surface treatment using ozone and ultraviolet light. (Preparation for vacuum deposition)

[0125] After cleaning, each layer was deposited on the surface-treated substrate by vacuum deposition using a vacuum deposition method, and each layer was laminated.

[0126] First, the glass substrate was placed in a vacuum deposition chamber. -4 The pressure was reduced to Pa. Then, each layer was formed in the following order according to the film formation conditions. (Fabrication of Hole Injection Layer 103)

[0127] Sublimation-purified N-[1,1'-biphenyl]-4-yl-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine and 1,2,3-tris[(4-cyano-2,3,5,6-tetrafluorophenyl)methylene]cyclopropane were deposited at a rate of 0.15 nm / s to form a 55 nm thick hole injection layer. (Preparation of First Hole Transport Layer 1051)

[0128] A 10 nm thick film of N-[1,1'-biphenyl]-4-yl-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine was formed at a rate of 0.15 nm / sec to form a first hole transport layer. (Fabrication of second hole transport layer 1052)

[0129] A 10 nm thick film of N-phenyl-N-(9,9-diphenylfluoren-2-yl)-N-(1,1′-biphenyl-4-yl)amine was formed at a rate of 0.15 nm / sec to form a second hole transport layer. (Fabrication of the light-emitting layer 106)

[0130] The light-emitting layer was formed by depositing a 25 nm thick film of 3-(10-phenyl-9-anthryl)-dibenzofuran and 2,7-bis[N,N-di-(4-tertbutylphenyl)]amino-bisbenzofurano-9,9'-spirofluorene in a mass ratio of 95:5 at a deposition rate of 0.18 nm / s. (Fabrication of First Electron Transport Layer 1071)

[0131] Sublimation-purified 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)[1,1'-biphenyl]-3-yl]-4,6-diphenyl-1,3,5-triazine was deposited at a rate of 0.15 nm / sec to form a 5 nm film to form a first electron transport layer. (Preparation of second electron transport layer 1072)

[0132] A 25 nm thick film was formed by mixing 4,6-diphenyl-2-[4'-{2-(1-naphthyl)pyridin-5-yl}-1,1'-biphenyl-4-yl]-1,3,5-triazine (Compound A-67) synthesized in Synthesis Example 1 and 8-hydroxyquinolinolate lithium (hereinafter referred to as Liq) in a mass ratio of 50:50 to form a second electron transport layer. The film formation rate was 0.15 nm / sec. (Fabrication of the cathode 108)

[0133] Finally, a metal mask was placed perpendicular to the ITO stripes on the substrate, and the cathode 108 was formed. The cathode had a two-layer structure, with silver / magnesium (mass ratio 1 / 10) and silver deposited in that order to thicknesses of 80 nm and 20 nm, respectively. The silver / magnesium deposition rate was 0.5 nm / sec, and the silver deposition rate was 0.2 nm / sec.

[0134] As a result, the light-emitting area of ​​4mm as shown in Figure 2 2 An organic electroluminescent device 100 was produced. The thickness of each film was measured using a stylus film thickness measuring instrument (DEKTAK, manufactured by Bruker).

[0135] The device was then sealed in a nitrogen atmosphere glove box with an oxygen and moisture concentration of 1 ppm or less by sealing the glass sealing cap and the film-formed substrate (device) with bisphenol F epoxy resin (manufactured by Nagase ChemteX Corporation).

[0136] A direct current was applied to the organic electroluminescent device fabricated as described above, and the light-emitting characteristics were evaluated using a luminance meter (product name: BM-9, manufactured by Topcon Technohouse Co., Ltd.). 2 The current efficiency (cd / A) was measured when the current was passed through the electrode.

[0137] The voltage and current efficiency are relative values, with the result of Comparative Example Element 1 set as the reference value (100). Table 2 shows the measurement results. <Element Example 2>

[0138] An organic electroluminescent device was fabricated and evaluated in the same manner as in Element Example 1, except that compound (A-70) synthesized in Synthesis Example 2 was used instead of compound (A-65) in Element Example 1. The measurement results obtained are shown in Table 2. <Element Example 3>

[0139] An organic electroluminescent device was fabricated and evaluated in the same manner as in Element Example 1, except that compound (A-91) synthesized in Synthesis Example 3 was used instead of compound (A-65) in Element Example 1. The measurement results obtained are shown in Table 2. <Comparative element example 1>

[0140] An organic electroluminescent device was fabricated and evaluated in the same manner as in Device Example 1, except that 2,4-bis[(1,1'-biphenyl)-4-yl]-6-[4'-(4-pyridyl)1,1'-biphenyl-4-yl]-1,3,5-triazine (ETL-1) described in Patent Document 1 was used instead of compound (A-65). The measurement results obtained are shown in Table 2.

[0141] [Table 2]

[0142] The cyclic azine compound (1) according to one embodiment of the present invention can provide an organic electroluminescent device excellent in driving voltage and luminous efficiency by using the compound.

[0143] Furthermore, the cyclic azine compound (1) according to one aspect of the present invention can be used as an electron transport material for organic electroluminescent elements, which contributes to the fabrication of organic electroluminescent elements having low driving voltage and excellent luminous efficiency. Furthermore, the cyclic azine compound (1) can provide organic electroluminescent elements having low power consumption and high luminous efficiency. [Explanation of symbols]

[0144] 100. Organic electroluminescent devices 1 board 2 Anode 3. Hole injection layer 4. Hole transport layer 5. Light-emitting layer 6 Electron transport layer 7 Electron injection layer 8 cathode 101 Substrate 102 Anode 103 Hole injection layer 1051 First hole transport layer 1052 Second hole transport layer 106 Light-emitting layer 1071 First electron transport layer 1072 Second electron transport layer 108 Cathode

Claims

1. An azine compound represented by the following formula (1): Formula (1) 【Chemical 1】 During the ceremony, Ar １ , Ar ２ independently represent a phenyl group or a biphenyl group. Ar ３ represents a phenyl group, a naphthyl group, or a phenanthrenyl group. L １ represents a divalent 6-membered ring linking group. The divalent 6-membered ring linking group is a 3,6-pyridylene group or a 2,5-pyrimidylene group which may be substituted with a methyl group. n １ represents an integer of 1 or 2. n ２ represents an integer of 0 or 1.

2. The azine compound according to claim 1, wherein the divalent 6-membered ring linking group is a 3,6-pyridylene group or a 2,5-pyrimidylene group optionally substituted with a methyl group at the 2-position.

3. A material for an organic electroluminescent device, comprising the azine compound according to claim 1 or 2.

4. An organic electroluminescent device comprising the azine compound according to claim 1 or 2.

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