Triazine compounds, materials for organic electroluminescent devices, electron transport materials for organic electroluminescent devices, and organic electroluminescent devices.

Abstract

To provide a triazine compound that contributes to forming an organic electroluminescent device having excellent drive voltage and durability.SOLUTION: A 1,3,5-triazine compound has a specific structure, bound to a phenyl group through any one group of the formulae (2-1) to (2-5).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a triazine compound, a material for an organic electroluminescent device, an electron transport material for an organic electroluminescent device, and an organic electroluminescent device. [Background technology]

[0002] Organic electroluminescent elements are used not only in small displays but also in applications such as large televisions and lighting, and their development is being actively pursued.

[0003] In recent years, market demand for organic electroluminescent devices has been steadily increasing, and there is a growing need for materials that excel in current efficiency, drive voltage characteristics, and long lifespan.

[0004] Here, Patent Document 1 discloses a triazine derivative substituted with a 4'-phenyl-5'-1,1':2',1”-terphenyl group. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-128561 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, the device lifetime of the triazine derivative described in Patent Document 1 is relatively short compared to the other compounds disclosed in Patent Document 1. Therefore, it is difficult to say that the 4'-phenyl-5'-1,1':2',1”-terphenyl group is useful as a substituent for triazine derivatives, and further improvement in device lifetime is required.

[0007] Therefore, one aspect of the present invention is aimed at providing a triazine compound, an organic electroluminescent element material, and an electron transport material for organic electroluminescent elements that contribute to the fabrication of an organic electroluminescent element with a low driving voltage and excellent durability.

[0008] Another aspect of the present invention is directed toward providing an organic electroluminescent element with a low driving voltage and excellent durability. [Means for solving the problem]

[0009] According to one aspect of the present invention, a triazine compound represented by formula (1) is provided:

[0010] [ka]

[0011] In formula (1), A represents an aryl group with 6 to 20 carbon atoms; B is an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cyano group, An aryl group having 6 to 20 carbon atoms, which may be substituted with one or more groups selected from the group consisting of diarylboryl groups and phosphine oxide groups, Represents a heteroaryl group with 4 to 30 carbon atoms, containing either an oxygen atom or a sulfur atom; Ar 1 ~Ar 3 Each of them operates independently. A C6-C18 aryl group which may be substituted with one or more groups selected from the group consisting of C1-C12 alkyl groups, C3-C20 cycloalkyl groups, cyano groups, diarylboryl groups, and phosphine oxide groups. They may be substituted with methyl or phenyl groups. Pyridinyl group, or, Represents a heteroaryl group with 4 to 18 carbon atoms, containing either an oxygen atom or a sulfur atom; n represents an integer between 0 and 1; L represents any one of the groups of formulas (2-1) to (2-5).

[0012] [Chemical formula]

[0013] According to another aspect of the present invention, a material for an organic electroluminescent device containing the above triazine compound is provided.

[0014] According to another aspect of the present invention, an electron transport material for an organic electroluminescent device containing the above triazine compound is provided.

[0015] According to another aspect of the present invention, an organic electroluminescent device containing the above triazine compound is provided. [Advantages of the Invention]

[0016] According to one aspect of the present invention, it is possible to provide a triazine compound, a material for an organic electroluminescent device, and an electron transport material for an organic electroluminescent device, which contribute to the production of an organic electroluminescent device having a low driving voltage and excellent durability.

[0017] According to another aspect of the present invention, it is possible to provide an organic electroluminescent device having a low driving voltage and excellent durability. [Brief Description of the Drawings]

[0018] [Figure 1] It is a schematic cross-sectional view showing an example of the laminated structure of an organic electroluminescent device containing a triazine compound according to one aspect of the present invention. [Figure 2] It is a schematic cross-sectional view showing an example (Device Example-1) of the laminated structure of an organic electroluminescent device containing a triazine compound according to one aspect of the present invention. [Modes for Carrying Out the Invention]

[0019] Hereinafter, the triazine compound according to one aspect of the present invention will be described in detail. [Triazine Compound] A triazine compound according to one aspect of the present invention is represented by formula (1):

[0020] [ka]

[0021] In formula (1), A represents an aryl group with 6 to 20 carbon atoms; B is an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cyano group, An aryl group having 6 to 20 carbon atoms, which may be substituted with one or more groups selected from the group consisting of diarylboryl groups and phosphine oxide groups, Represents a heteroaryl group with 4 to 30 carbon atoms, containing either an oxygen atom or a sulfur atom; Ar 1 ~Ar 3 Each of them operates independently. A C6-C18 aryl group which may be substituted with one or more groups selected from the group consisting of C1-C12 alkyl groups, C3-C20 cycloalkyl groups, cyano groups, diarylboryl groups, and phosphine oxide groups. A pyridinyl group, which may be substituted with a methyl group or a phenyl group, Represents a heteroaryl group with 4 to 18 carbon atoms, containing either an oxygen atom or a sulfur atom; n represents an integer between 0 and 1; L represents one of the bases in equations (2-1) to (2-5).

[0022] [ka]

[0023] Hereinafter, the triazine compound represented by formula (1) may be referred to as triazine compound (1). The definitions of substituents in triazine compound (1) and preferred specific examples are as follows. In formula (1), A represents an aryl group with 6 to 20 carbon atoms; B is an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cyano group, An aryl group having 6 to 20 carbon atoms, which may be substituted with one or more groups selected from the group consisting of diarylboryl groups and phosphine oxide groups, Represents a heteroaryl group with 4 to 30 carbon atoms, containing either an oxygen atom or a sulfur atom; Ar 1 ~Ar 3 Each of them operates independently. A C6-C18 aryl group which may be substituted with one or more groups selected from the group consisting of C1-C12 alkyl groups, C3-C20 cycloalkyl groups, cyano groups, diarylboryl groups, and phosphine oxide groups. A pyridinyl group, which may be substituted with a methyl group or a phenyl group, Represents a heteroaryl group with 4 to 18 carbon atoms, containing either an oxygen atom or a sulfur atom; n represents an integer between 0 and 1; L represents one of the bases in equations (2-1) to (2-5).

[0024] In A, preferred examples of aryl groups having 6 to 20 carbon atoms include phenyl, naphthalenyl, biphenylyl, naphthylphenyl, phenylnaphthyl, binaphthyl, phenantrenyl, anthracenyl, terphenyl, and triphenylenyl groups. Among these, phenyl, biphenylyl, naphthylphenyl, phenylnaphthyl, binaphthyl, and terphenyl groups are more preferred, and it is most preferable that one group be selected from formulas (A-1) to (A-10).

[0025] [ka]

[0026] In B, the aryl group having 6 to 20 carbon atoms is preferably a phenyl group, naphthalenyl group, biphenylyl group, naphthylphenyl group, phenylnaphthyl group, binaphthyl group, phenantrenyl group, anthracenyl group, terphenyl group, or triphenylenyl group. These groups may be substituted with one or more groups selected from the group consisting of alkyl groups having 1 to 12 carbon atoms, cycloalkyl groups having 3 to 20 carbon atoms, cyano groups, diarylboryl groups, and phosphine oxide groups. Among the aryl groups, the phenyl group, biphenylyl group, naphthylphenyl group, phenylnaphthyl group, and terphenyl group are more preferred, and these groups can also be suitably used when substituted with a cyano group, with the most preferred being one group selected from formulas (B-1) to (B-27).

[0027] [ka]

[0028] [ka]

[0029] In B, the heteroaryl groups having 4 to 18 carbon atoms are: 1-dibenzofuranyl group, 2-dibenzofuranyl group, 3-dibenzofuranyl group, 4-dibenzofuranyl group, 1-dibenzothienyl group, 2-dibenzothienyl group, 3-dibenzothienyl group, 4-dibenzothienyl group, spiro[9H-fluorene-9,9'-[9H]xanthene]-1-yl group, spiro[9H-fluorene-9,9'-[9H]xanthene]-2-yl group, spiro[9H-fluorene-9, A 9'-[9H]xanthene]-3-yl group, a spiro[9H-fluorene-9,9'-[9H]xanthene]-4-yl group, a spiro[9H-fluorene-9,9'-[9H]xanthene]-1'-yl group, a spiro[9H-fluorene-9,9'-[9H]xanthene]-2'-yl group, a spiro[9H-fluorene-9,9'-[9H]xanthene]-3'-yl group, or a spiro[9H-fluorene-9,9'-[9H]xanthene]-4'-yl group is preferred.

[0030] Ar 1 ~Ar 3 In the formula, the aryl group having 6 to 18 carbon atoms is preferably a phenyl group, 1-naphthalenyl group, 2-naphthalenyl group, 2-biphenylyl group, 3-biphenylyl group, 4-biphenylyl group, 2-(1-naphthalenyl)phenyl group, 3-(1-naphthalenyl)phenyl group, 4-(1-naphthalenyl)phenyl group, 2-(2-naphthalenyl)phenyl group, 3-(2-naphthalenyl)phenyl group, 4-(2-naphthalenyl)phenyl group, 4-phenylnaphthalen-1-yl group, 5-phenylnaphthalen-1-yl group, 6-phenylnaphthalen-2-yl group, 7-phenylnaphthalen-2-yl group, 2-phenanthrenyl group, 3-phenanthrenyl group, 9-phenanthrenyl group, 9-anthracenyl group, p-terphenyl group, and 2-triphenylenyl group. These groups may be substituted with one or more selected from the group consisting of an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cyano group, a diarylboril group, and a phosphine oxide group, but an unsubstituted phenyl group, 1-naphthalenyl group, or 2-naphthalenyl group is particularly preferred.

[0031] Ar 1 ~Ar 3In this context, pyridinyl groups that may be substituted with a methyl or phenyl group are: 2-pyridinyl group, 3-pyridinyl group, 4-pyridinyl group, 2-methylpyridine-3-yl group, 2-methylpyridine-4-yl group, 2-methylpyridine-5-yl group, 2-methylpyridine-6-yl group, 3-methylpyridine-2-yl group, 3-methylpyridine-4-yl group, 3-methylpyridine-5-yl group, 3-methylpyridine-6-yl group, 4-methylpyridine-2-yl group, 4-methylpyridine-3-yl group, 2 ,6-dimethylpyridine-3-yl group, 2,6-dimethylpyridine-4-yl group, 3,6-dimethylpyridine-2-yl group, 3,6-dimethylpyridine-4-yl group, 3,6-dimethylpyridine-5-yl group, 2-phenylpyridine-3-yl group, 2-phenylpyridine-4-yl group, 2-phenylpyridine-5-yl group, 2-phenylpyridine-6-yl group, 3-phenylpyridine-2-yl group, 3-phenylpyridine-4-yl group, 3-phenylpyridine-5-yl group, 3-phenylpyridine-6- Iyl group, 4-phenylpyridine-2-yl group, 4-phenylpyridine-3-yl group, 2,6-diphenylpyridine-3-yl group, 2,6-diphenylpyridine-4-yl group, 3,6-diphenylpyridine-2-yl group, 3,6-diphenylpyridine-4-yl group, 3,6-diphenylpyridine-5-yl group, 4,6-diphenylpyridine-2-yl group, 2-methyl-6-phenylpyridine-3-yl group, 2-methyl-6-phenylpyridine-4-yl group, 3-methyl-6-phenylpyridine-2-yl Preferred examples include the group, 3-methyl-6-phenylpyridine-4-yl group, 3-methyl-6-phenylpyridine-5-yl group, 4-methyl-6-phenylpyridine-2-yl group, 6-methyl-2-phenylpyridine-3-yl group, 6-methyl-2-phenylpyridine-4-yl group, 6-methyl-3-phenylpyridine-2-yl group, 6-methyl-3-phenylpyridine-4-yl group, 6-methyl-3-phenylpyridine-5-yl group, and 6-methyl-4-phenylpyridine-2-yl group.

[0032] Ar 1 ~Ar 3In this context, preferred examples of heteroaryl groups having 4 to 18 carbon atoms and containing an oxygen atom or a sulfur atom include 1-dibenzofuranyl, 2-dibenzofuranyl, 3-dibenzofuranyl, 4-dibenzofuranyl, 1-dibenzothienyl, 2-dibenzothienyl, 3-dibenzothienyl, and 4-dibenzothienyl groups.

[0033] In a triazine compound according to one embodiment of the present invention represented by formula (1), preferred A, B, Ar 1 ~Ar 3 The first to fifth embodiments, which are combinations of the above, are as follows: • First aspect A The group is a phenyl group, a naphthalenyl group, a biphenylyl group, a naphthylphenyl group, a phenylnaphthyl group, a binaphthyl group, a phenantrenyl group, an anthracenyl group, a terphenyl group, or a triphenylenyl group; B, A triazine compound which is a phenyl group, naphthalenyl group, biphenylyl group, naphthylphenyl group, phenylnaphthyl group, binaphthyl group, phenantrenyl group, anthracenyl group, terphenyl group, triphenylenyl group, dibenzofuranyl group, dibenzothienyl group, or spiro[9H-fluoren-9,9'-[9H]xanthene]-yl group, which may be substituted with one or more groups selected from the group consisting of C1-C12 alkyl groups, C3-C20 cycloalkyl groups, cyano groups, diarylboryl groups, and phosphine oxide groups. • Second aspect A It is a phenyl group, biphenylyl group, naphthylphenyl group, phenylnaphthyl group, binaphthyl group, or terphenyl group; B, A triazine compound which is a phenyl group, biphenylyl group, naphthylphenyl group, phenylnaphthyl group, or terphenyl group, which may be substituted with a cyano group. • Third aspect A is one base selected from equations (A-1) to (A-9); A triazine compound in which B is one group selected from formulas (B-1) to (B-27). • Fourth aspect Ar 1 ~Ar 3 A triazine compound in which each of the following groups may be independently substituted with a cyano group: phenyl group, 1-naphthyl group, 2-naphthyl group, 2-pyridinyl group, 3-pyridinyl group, 4-pyridinyl group, 1-dibenzofuranyl group, 2-dibenzofuranyl group, 4-dibenzofuranyl group, 1-dibenzothienyl group, 2-dibenzothienyl group, 3-dibenzothienyl group, or 4-dibenzothienyl group. • Fifth aspect Ar 1 ~Ar 3 However, each triazine compound is a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-pyridinyl group, a 3-pyridinyl group, or a 4-pyridinyl group, which may be independently substituted with a cyano group. [Specific examples of triazine compounds (1)] Among the triazine compounds according to one aspect of the present invention represented by formula (1), particularly preferred specific examples include those from formulas (1-1) to (1-99), but the triazine compounds according to one aspect of the present invention are not limited to these.

[0034] [ka]

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] The uses of triazine compound (1) are described below. <Materials for organic electroluminescent devices, electron transport materials for organic electroluminescent devices> The triazine compound (1) is not particularly limited, but can be used, for example, as a material for organic electroluminescent devices. Furthermore, the triazine compound (1) can be used, for example, as an electron transport material for organic electroluminescent devices.

[0047] In other words, the material for an organic electroluminescent device according to one aspect of the present invention contains a triazine compound (1). Furthermore, the electron transport material for an organic electroluminescent device according to one aspect of the present invention also contains a triazine compound (1). The material for an organic electroluminescent device and the electron transport material for an organic electroluminescent device containing a triazine compound (1) contribute to the production of organic electroluminescent devices with low driving voltage and excellent durability. <Organic electroluminescent element> An organic electroluminescent device according to one aspect of the present invention comprises a triazine compound (1).

[0048] The configuration of the organic electroluminescent element is not particularly limited, but for example, the configurations shown in (i) to (vi) below can be cited. (i): Anode / Emitting layer / Cathode (ii): Anode / Hole transport layer / Emitting layer / Cathode (iii): Anode / Emitting layer / Electron transport layer / Cathode (iv): Anode / Hole transport layer / Emitting layer / Electron transport layer / Cathode (v): Anode / Hole injection layer / Hole transport layer / Emitting layer / Electron transport layer / Electron injection layer / Cathode (vi): Anode / Hole injection layer / Charge generation layer / Hole transport layer / Emitting layer / Electron transport layer / Cathode Hereinafter, an organic electroluminescent element according to one aspect of the present invention will be described in more detail with reference to Figure 1, using the configuration described in (vi) above as an example. Figure 1 is a schematic cross-sectional view showing an example of a stacked configuration of an organic electroluminescent element containing a triazine compound according to one aspect of the present invention.

[0049] The organic electroluminescent element shown in Figure 1 has a so-called bottom-emission type element configuration, but the organic electroluminescent element according to one aspect of the present invention is not limited to a bottom-emission type element configuration. That is, the organic electroluminescent element according to one aspect of the present invention may have a top-emission type element configuration or other known element configurations.

[0050] The organic electroluminescent element 100 comprises a substrate 1, an anode 2, a hole injection layer 3, a charge generation layer 4, a hole transport layer 5, a light-emitting layer 6, an electron transport layer 7, and a cathode 8 in this order. However, some of these layers may be omitted, or other layers may be added. For example, an electron injection layer may be provided between the electron transport layer 7 and the cathode 8, the charge generation layer 4 may be omitted, and the hole transport layer 5 may be directly provided on the hole injection layer 3. Furthermore, a single layer that combines the functions of multiple layers, such as an electron injection / transport layer that combines the functions of an electron injection layer and an electron transport layer in a single layer, may be provided instead of the multiple layers. In addition, for example, the single-layer hole transport layer 5 and the single-layer electron transport layer 7 may each consist of multiple layers. [Layer containing a triazine compound represented by formula (1)] The organic electroluminescent device contains the triazine compound represented by formula (1) in one or more layers selected from the group consisting of an emissive layer and a layer between the emissive layer and the cathode. Therefore, in the example configuration shown in Figure 1, the organic electroluminescent device 100 contains the triazine compound (1) in at least one layer selected from the group consisting of an emissive layer 6 and an electron transport layer 7. In particular, it is preferable that the electron transport layer 7 contains the triazine compound (1). The triazine compound (1) may be included in multiple layers of the organic electroluminescent device, and if an electron injection layer is provided between the electron transport layer and the cathode, the electron injection layer may also contain the triazine compound (1).

[0051] In the following, we will describe an organic electroluminescent device 100 in which the electron transport layer 7 contains a triazine compound (1). [Circuit board 1] There are no particular limitations on the substrate; for example, glass plates, quartz plates, and plastic plates can be used. Also, in a configuration where light is extracted from the substrate 1, the substrate 1 is transparent to the wavelength of light.

[0052] Examples of light-transmitting plastic films include films made from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), cellulose acetate propionate (CAP), and the like. [Anode 2] An anode 2 is provided on substrate 1 (on the side of hole injection layer 3).

[0053] In the case of an organic electroluminescent device in which light is extracted by passing it through an anode, the anode is formed of a material that allows the light to pass through or substantially allows the light to pass through.

[0054] Transparent materials used for the anode are not particularly limited, but examples include indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide, aluminum-doped tin oxide, magnesium-indium oxide, nickel-tungsten oxide, other metal oxides, metal nitrides such as gallium nitride, metal selenides such as zinc selenide, and metal sulfides such as zinc sulfide.

[0055] In the case of an organic electroluminescent device that extracts light only from the cathode, the transmission characteristics of the anode are not important. Therefore, examples of materials that can be used for the anode in this case include gold, iridium, molybdenum, palladium, and platinum.

[0056] A buffer layer (electrode interface layer) may be provided on the anode. [Hole injection layer 3, hole transport layer 5] Between the anode 2 and the light-emitting layer 6 (described later), a hole injection layer 3, a charge generation layer 4 (described later), and a hole transport layer 5 are provided in this order from the anode 2 side.

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

[0058] Furthermore, the hole injection layer and 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 electron transport layer to the light-emitting layer are prevented from leaking into the hole injection layer and / or hole transport layer by the electron barrier present at the interface between the light-emitting layer and the hole injection layer and / or hole transport layer. As a result, these electrons accumulate at the interface within the light-emitting layer, leading to effects such as improved current efficiency, and resulting in an organic electroluminescent element with excellent light-emitting performance.

[0059] The hole injection layer and hole transport layer materials must possess at least one of the following properties: hole injection properties, hole transport properties, or electron barrier properties. The hole injection layer and hole transport layer materials may be either organic or inorganic.

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

[0061] Specific examples of aromatic tertiary amine compounds and styrylamine compounds include N,N,N',N'-tetraphenyl-4,4'-diaminophenyl, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[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-(3-methylphenyl)-N-phenylamino]triphenylamine (MTDATA).

[0062] In addition, inorganic compounds such as p-type Si and p-type SiC can also be cited as examples of materials for hole injection layers and hole transport layers.

[0063] The hole injection layer and hole transport layer may be a single-layer structure made of one or more materials, or a laminated structure made of multiple layers of the same or different compositions. [Charge generation layer 4] A charge generation layer 4 may be provided between the hole injection layer 3 and the hole transport layer 5.

[0064] There are no particular restrictions on the material of the charge generation layer, but examples include dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonnitrile (HAT-CN).

[0065] The charge generation layer may be a single-layer structure made of one or more materials, or it may be a laminated structure made of multiple layers of the same or different compositions. [Emitting layer 6] A light-emitting layer 6 is provided between the hole transport layer 5 and the electron transport layer 7, which will be described later.

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

[0067] The luminescent layer may consist of a single low-molecular-weight material or a single polymer material, but more commonly, it consists of a host material doped with a guest compound. Luminescence primarily arises from the dopant and can have any color. There are two types of dopants: fluorescent dopants and phosphorescent dopants.

[0068] Examples of host materials include compounds having biphenyl groups, fluorenyl groups, triphenylsilyl groups, carbazole groups, pyrenyl groups, and anthryl groups. More specifically, 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-phenylphenylquinazoline-2-yl)carbazol, 9,10-bis(biphenyl)anthracene, etc.

[0069] Examples of fluorescent dopants include anthracene, pyrene, tetracene, xanthene, perylene, rubrene, coumarin, rhodamine, quinacridone, dicyanomethylenepyran compounds, thiopyran compounds, polymethine compounds, pyrylium, thiapyrillium compounds, fluorene derivatives, perifurante derivatives, indenoperylene derivatives, bis(azinyl)amineboron compounds, bis(azinyl)methane compounds, carbostyryl compounds, etc. A 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 also be contained in layers adjacent to the light-emitting layer (hole transport layer 5 or electron transport layer 7). This can further increase the current efficiency of the organic electroluminescent device.

[0073] The light-emitting layer may be a single-layer structure made of one or more materials, or it may be a laminated structure made of multiple layers of the same or different compositions. [Electron transport layer 7] An electron transport layer 7 is provided between the light-emitting layer 6 and the cathode 8, which will be described later.

[0074] The electron transport layer has the function of transferring 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.

[0075] As mentioned above, the electron transport layer preferably contains a triazine compound represented by formula (1) above.

[0076] Furthermore, the electron transport layer may also contain conventionally known electron transport materials in addition to the triazine compound (1). Examples of conventionally known electron transport materials include lithium 8-hydroxyquinolinate (Liq), bis(8-hydroxyquinolinate)zinc, bis(8-hydroxyquinolinate)copper, bis(8-hydroxyquinolinate)manganese, tris(8-hydroxyquinolinate)aluminum, tris(2-methyl-8-hydroxyquinolinate)aluminum, tris(8-hydroxyquinolinate)gallium, bis(10-hydroxybenzo[h]quinolinate)beryllium, bis(10-hydroxybenzo[h]quinolinate)zinc, bis(2-methyl-8-quinolinate)chlorogallium, bis(2-methyl-8-quinolinate)(o-crezolate)gallium, and bis(2-methyl-8-quinolinate)-1-naphtholate. Examples include aluminum, or bis(2-methyl-8-quinolinate)-2-naphtholate gallium, 2-[3-(9-phenantrenyl)-5-(3-pyridinyl)phenyl]-4,6-diphenyl-1,3,5-triazine, and 2-(4,''-di-2-pyridinyl[1,1':3',1''-terphenyl]-5-yl)-4,6-diphenyl-1,3,5-triazine, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), Bphen (4,7-diphenyl-1,10-phenanthroline), BAlq (bis(2-methyl-8-quinolinate)-4-(phenylphenolate)aluminum), and bis(10-hydroxybenzo[h]quinolinate)beryllium).

[0077] The electron transport layer may be a single-layer structure made of one or more materials, or it may be a laminated structure made of multiple layers of the same or different compositions.

[0078] When the electron transport layer has a two-layer structure with the first electron transport layer on the light-emitting layer side and the second electron transport layer on the cathode side, it is preferable that the second electron transport layer contains a triazine compound (1). [Cathode 8] A cathode 8 is provided on the electron transport layer 7.

[0079] In the case of an organic electroluminescent element configured to extract only the light emitted after passing through the anode, the cathode can be formed from any conductive material.

[0080] 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.

[0081] A buffer layer (electrode interface layer) may be provided on the cathode (electron transport layer side). [Method of forming each layer] Each layer, excluding the electrodes (anode and cathode) described above, can be formed by thinning the material of each layer (along with binder resins and solvents as needed) using known methods such as vacuum deposition, spin coating, casting, or the LB (Langmuir-Blodgett method).

[0082] There are no particular restrictions on the thickness of each layer formed in this way, and it can be selected as appropriate depending on the situation, but it is usually in the range of 5 nm to 5 μm.

[0083] The anode and cathode can be formed by thinning the electrode material using methods such as vapor deposition or sputtering. The pattern may be formed via a mask of the desired shape during vapor deposition or sputtering, or the pattern may be formed by photolithography after the thin film has been formed by vapor deposition or sputtering.

[0084] The film thickness of the anode and cathode is preferably 1 μm or less, and more preferably 10 nm to 200 nm.

[0085] An organic electroluminescent element according to one aspect of the present invention may be used as a type of lamp, such as for illumination or as an exposure light source, or as a projection device that projects images, or as a display device that directly displays still or moving images. When used as a display device for video playback, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. Furthermore, by using two or more organic electroluminescent elements of this embodiment having different emission colors, it is possible to create a full-color display device.

[0086] Furthermore, one embodiment of the present invention, the triazine compound (1), can be synthesized by appropriately combining known reactions (for example, the Suzuki-Miyaura cross-coupling reaction). [Examples]

[0087] The present invention will be described in more detail below based on examples, but the present invention is not to be limited in any way by these examples.

[0088] 1 1H-NMR measurements were performed using Gemini200 (Varian).

[0089] The glass transition temperature was measured using a DSC7020 (manufactured by Hitachi High-Tech Science Corporation).

[0090] The light emission characteristics of the organic electroluminescent element were evaluated by applying a DC current to the fabricated element at room temperature and using a luminance meter (product name: BM-9, manufactured by Topcon Techno House Co., Ltd.).

[0091] Synthesis Example 1: Synthesis of Compound (1-73)

[0092] [ka]

[0093] [ka]

[0094] Under a nitrogen atmosphere, tetrahydrofuran (170 mL) was added to a flask containing 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 (10.0 g, 17.02 mmol), 2,4,5-trichlorobromobenzene (4.9 g, 18.72 mmol), and Pd(PPh3)4 (393 mg, 0.34 mmol). Further, 25.5 mL, 51.06 mmol, of 2 M potassium phosphate aqueous solution was added, and the mixture was stirred at 70°C for 22 hours. After cooling to room temperature, the precipitated solid was collected by suction filtration and washed with water, and then with methanol. The obtained solid was dissolved in toluene and then recrystallized to obtain 2,4-bis([1,1'-biphenyl]-4-yl)-6-(2',4',5'-trichloro[1,1'-biphenyl]-4-yl-1,3,5-triazine (yield 9.8g, yield 90%).

[0095] Under a nitrogen atmosphere, tetrahydrofuran (310 ml) was added to a flask containing 2,4-bis([1,1'-biphenyl]-4-yl)-6-(2',4',5'-trichloro[1,1'-biphenyl]-4-yl-1,3,5-triazine (9.8 g, 15.30 mmol), phenylboronic acid (11.2 g, 91.83 mmol), palladium acetate (69 mg, 0.31 mmol), and 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (X-Phos) (292 mg, 0.62 mmol). Furthermore, 2M potassium phosphate was added. A 46 ml, 91.8 mmol aqueous solution of lium was added, and the mixture was stirred at 70°C for 23 hours. After cooling to room temperature, the precipitated solid was collected by suction filtration and washed with water and ethanol. The obtained solid was dissolved in 500 mL of chlorobenzene, and 1.0 g of activated carbon was added and the mixture was heated and stirred at 100°C for 2 hours. The activated carbon was filtered off by suction filtration using a Kiriyama funnel lined with Celite, and the filtrate was removed by reduced pressure distillation. Further recrystallization from a 1000 ml solution of toluene yielded a white solid of compound (1-73) (yield 5.8 g, yield 49%). The glass transition temperature was 158°C.

[0096] 1 H-NMR(CDCl3)δ(ppm):8.91(d,4H),8.76(d,2H),7.89(d,4H),7.78(m,4H),7 .65(s,1H),7.58(s,1H),7.45-7.54(m,6H),7.40(m,2H),7.18-7.35(m,15H). Synthesis Example 2: Synthesis of Compounds (1-10)

[0097] [ka]

[0098] Under a nitrogen atmosphere, tetrahydrofuran (40 ml) was added to a flask containing 2,4-bis([1,1'-biphenyl]-4-yl)-6-chloro-1,3,5-triazine (1.60 g, 3.81 mmol), 2-[5'-phenyl(1,1':4',1''-terphenyl)-2'-yl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.97 g, 4.57 mmol), and Pd(PPh3)4 (88.1 mg, 0.0762 mmol). Further, 2M potassium phosphate aqueous solution (5.7 ml, 21.4 mmol) was added, and the mixture was stirred at 70°C for 20 hours. After cooling to room temperature, the precipitated solid was collected by suction filtration and washed with water and ethanol. The obtained solid was dissolved in toluene (100 mL), activated carbon (0.4 g) was added, and the mixture was heated and stirred at 100 °C for 1 hour. The activated carbon was filtered off by suction filtration using a Kiriyama funnel lined with Celite, and the filtrate was removed by reduced pressure distillation. Further recrystallization from a toluene (15 ml) solution yielded a white solid of compound (1-10) (yield 1.9 g, yield 76%). The glass transition temperature was 130 °C.

[0099] 1 H-NMR(CDCl3)δ(ppm):8.45(s,1H),8.42(d,J=8.4Hz,4H),7.67-7.71(m,9H),7.65(s,1H),7.49(dd,J=8. 0Hz,8.0Hz,4H),7.44-7.46(m,2H),7.42(dd,J=1.2Hz,1.2Hz,1H),7.41-7.38(m,4H),7.37-7.27(m,9H). Next, device evaluation was performed using the obtained compounds. Element Example 1 (See Figure 2) (Prepare circuit board 101 and anode 102) As a substrate with an anode on its surface, a glass substrate with transparent ITO electrodes was prepared, on which a 2 mm wide indium-tin (ITO) film (thickness 110 nm) was patterned in a stripe pattern. Next, this substrate was cleaned with isopropyl alcohol and then surface-treated by ozone ultraviolet cleaning. (Preparation for vacuum deposition) After cleaning and surface treatment, each layer was deposited using a vacuum deposition method onto the substrate, thereby forming a laminated structure of each layer.

[0100] First, the glass substrate is introduced into the vacuum deposition chamber, and 1.0 × 10 -4 The pressure was reduced to Pa. Then, each layer was fabricated according to the deposition conditions for each layer, in the following order. (Preparation of hole injection layer 103) A hole-injection layer 103 was prepared by depositing a 10 nm film of sublimation-purified N-[1,1'-biphenyl]-4-yl-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9H-fluoren-2-amine and 1,2,3-tris[(4-cyano-2,3,5,6-tetrafluorophenyl)methylene]cyclopropane at a rate of 0.15 nm / second. (Preparation of the first hole transport layer 1051) N-[1,1'-biphenyl]-4-yl-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9H-fluoren-2-amine, purified by sublimation, was deposited at a rate of 0.15 nm / second to create a first hole transport layer 1051 with a thickness of 85 nm. (Preparation of the second hole transport layer 1052) N-phenyl-N-(9,9-diphenylfluoren-2-yl)-N-(1,1'-biphenyl-4-yl)amine, purified by sublimation, was deposited as a 5 nm film at a rate of 0.15 nm / second to create the second hole transport layer 1052. (Fabrication of the light-emitting layer 106) A luminescent layer 106 was fabricated by depositing 3-(10-phenyl-9-anthryl)-dibenzofuran and 2,7-bis[N,N-di-(4-tertbutylphenyl)]amino-bisbenzofuran-9,9'-spirofluorene at a ratio of 95:5 (mass ratio) to a film with a wavelength of 20 nm. The deposition rate was 0.18 nm / second. (Fabrication of the first electron transport layer 1071) The first electron transport layer 1071 was fabricated by depositing a 6 nm film of sublimation-purified 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)[1,1'-biphenyl]-3-yl]-4,6-diphenyl-1,3,5-triazine at a rate of 0.05 nm / second. (Fabrication of the second electron transport layer 1072) The compound (1-73) synthesized in Synthesis Example-1 and Liq were deposited in a 50:50 (mass ratio) ratio at a density of 25 nm to create the second electron transport layer 1072. The deposition rate was 0.15 nm / second. (Fabrication of cathode 108) Finally, a metal mask was positioned perpendicular to the ITO stripes on the substrate, and cathode 108 was deposited. The cathode consisted of a two-layer structure, with silver / magnesium (mass ratio 1 / 10) and silver deposited in that order, at 80 nm and 20 nm, respectively. The deposition rate for silver / magnesium was 0.5 nm / second, and the deposition rate for silver was 0.2 nm / second.

[0101] As a result, the light-emitting area is 4 mm² as shown in Figure 2. 2 Organic electroluminescent devices 100 were fabricated. The film thickness of each device was measured using a stylus-type film thickness analyzer (DEKTAK, Bruker).

[0102] Furthermore, this element was sealed in a nitrogen atmosphere glove box with oxygen and moisture concentrations of 1 ppm or less. The sealing was performed using bisphenol F type epoxy resin (manufactured by Nagase ChemteX Corporation) to seal the glass sealing cap and the film-deposited substrate (element).

[0103] A DC current was applied to the organic electroluminescent element fabricated as described above, and its luminescence characteristics were evaluated using a luminance meter (product name: BM-9, manufactured by Topcon Techno House). The luminescence characteristics were measured with a current density of 10 mA / cm². 2 The current efficiency (cd / A) was measured when a current was passed through the element, and the element lifespan (h) during continuous operation was also measured. Note that the element lifespan (h) was measured for the fabricated element with an initial brightness of 1000 cd / m². 2 The brightness decay time during continuous lighting when driven by was measured, and the brightness (cd / m²) was measured. 2 The time required for the value to decrease by 5% was measured.

[0104] Note that the voltage, current efficiency, and element lifespan are relative values ​​with the results from Element Comparative Example 1 set as the baseline (100). The obtained measurement results are shown in Table 1. Element Example-2 An organic electroluminescent device was fabricated and evaluated using the same method as in Element Example-1, except that compound (1-10) was used instead of compound (1-73). The obtained measurement results are shown in Table 1. Element Reference Example - 1 In Element Example 1, an organic electroluminescent device was fabricated and evaluated using the same method as in Element Example 1, except that compound (E-13) described in Patent Document 1 (JP 2017-128561 A) was used instead of compound (1-73). The obtained measurement results are shown in Table 1.

[0105] [ka]

[0106] [Table 1]

[0107] The triazine compound (1) according to one aspect of the present invention has a wide bandgap and a high triplet excitation level, and therefore can be suitably used not only in conventional fluorescent device applications but also in phosphorescent devices and organic electroluminescent devices utilizing thermally activated delayed fluorescence (TADF). [Explanation of Symbols]

[0108] 1,101 circuit boards 2,102 Anode 3,103 Hole injection layer 4. Charge generation layer 5,105 Hole transport layer 6,106 Emitting layer 7,107 Electron transport layer 8,108 Cathode 51,1051 First hole transport layer 52,1052 Second hole transport layer 71,1071 First electron transport layer 72,1072 Second electron transport layer 100 Organic Electroluminescent Devices

Claims

1. Triazine compound represented by formula (1): 【Chemistry 1】 In formula (1), A represents a phenyl group or a biphenylyl group; B represents a phenyl or biphenylyl group, which may be substituted with an alkyl group having 1 to 12 carbon atoms; Ar １ ~Ar ３ Each of these independently represents a phenyl group which may be substituted with an alkyl group having 1 to 12 carbon atoms; n represents an integer between 0 and 1; L represents the base shown in formula (2-1) or (2-2). 【Chemistry 2】

2. A and B are biphenylyl groups; Ar １ ~Ar ３ However, it is a phenyl group; The triazine compound according to claim 1, wherein L is the group of formula (2-1).

3. A material for an organic electroluminescent element comprising the triazine compound according to claim 1 or 2.

4. An electron transport material for an organic electroluminescent device comprising the triazine compound according to claim 1 or 2.

5. An organic electroluminescent element comprising the triazine compound according to claim 1 or 2.

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