Cyclic azine compounds, materials for organic electroluminescent devices, electron transport materials for organic electroluminescent devices, and organic electroluminescent devices.

Abstract

To provide a cyclic azine compound that contributes to preparing an organic electroluminescent device having excellent current efficiency, and a material for organic electroluminescent devices, an electron transport material for organic electroluminescent devices and an organic electroluminescent device each of which contains the cyclic azine compound.SOLUTION: A cyclic azine compound has a specific structure represented by formula (1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to cyclic azine compounds, materials for organic electroluminescent devices, electron transport materials for organic electroluminescent devices, and organic electroluminescent devices. [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] However, in recent years, market demand for organic electroluminescent devices has been increasing, and there is a need for materials that excel in current efficiency characteristics, driving voltage characteristics, and long life characteristics.

[0004] Here, Patent Document 1 discloses a cyclic azine compound having various substituents via naphthylene. Patent Document 2 also discloses a cyclic azine compound having a cyano group or a heteroaryl group containing a nitrogen atom via naphthylene. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Special Publication No. 2016-529211 [Patent Document 2] Special Publication No. 2019-534548 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, organic electroluminescent devices using the compounds disclosed in Patent Documents 1 and 2 as electron transport layers have insufficient current efficiency, and further improvements are needed.

[0007] One aspect of the present invention is directed to providing a cyclic azine compound, a material for an organic electroluminescent device, and an electron transport material for an organic electroluminescent device that contribute to the production of an organic electroluminescent device having excellent current efficiency.

[0008] Another aspect of the present invention is directed to providing an organic electroluminescent device having excellent current efficiency.

Means for Solving the Problems

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

[0010]

Chemical Formula

[0011] In formula (1), Ar ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ diarylboryl group, or Represents a phosphine oxide group, n represents an integer between 0 and 2. When n is 2, R can be the same or different. Np represents one of the bases selected from equations (2-1), (2-2), and (2-3).

[0012] [ka]

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

[0014] According to another aspect of the present invention, an electron transport material for an organic electroluminescent device is provided, comprising the above-mentioned cyclic azine compound.

[0015] According to another aspect of the present invention, an organic electroluminescent device comprising the above-mentioned cyclic azine compound is provided. [Effects of the Invention]

[0016] According to one aspect of the present invention, it is possible to provide a cyclic azine compound, a material for an organic electroluminescent device, and an electron transport material for an organic electroluminescent device that contribute to the fabrication of an organic electroluminescent device with excellent current efficiency.

[0017] According to another aspect of the present invention, an organic electroluminescent element with excellent current efficiency can be provided. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic cross-sectional view showing an example of a stacked configuration of an organic electroluminescent device containing a cyclic azine compound according to one aspect of the present invention. [Figure 2] This is a schematic cross-sectional view showing an example of a stacked configuration of an organic electroluminescent device containing a cyclic azine compound according to one aspect of the present invention (Device Example-1). [Modes for carrying out the invention]

[0019] A cyclic azine compound according to one embodiment of the present invention will be described in detail below. <Cyclic azine compounds> A cyclic azine compound according to one aspect of the present invention is represented by formula (1):

[0020] [ka]

[0021] In formula (1), Ar 1 teeth, Hydrogen atom, or, This represents an aryl group having 6 to 30 carbon atoms, or a heteroaryl group having 4 to 30 carbon atoms, which 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. Ar 2 teeth, This represents an aryl group having 6 to 30 carbon atoms, or a heteroaryl group having 4 to 30 carbon atoms, which 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. Ar 3 teeth, An aryl group having 6 to 18 carbon atoms, or This represents a heteroaryl group with 4 to 18 carbon atoms. R is Aryl groups with 6 to 12 carbon atoms, Alkyl alkyl groups having 1 to 12 carbon atoms, Cycloalkyl groups having 3 to 20 carbon atoms, Cyano group, diarylboryl group, or Represents a phosphine oxide group, n represents an integer between 0 and 2. When n is 2, R may be the same or different. Np represents any one group selected from the formulas (2-1), (2-2), and (2-3).

[0022] [Regarding the preferred combinations of

[0023] [Ar 1 ~Ar 3 , R] In the cyclic azine compound represented by formula (1), preferred Ar 1 ~Ar 3 , the combinations of R in the second to seventh aspects are as follows. ·Second aspect Ar 1 is an aryl group having 6 to 18 carbon atoms, which 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, and a cyano group, or a heteroaryl group having 4 to 25 carbon atoms, Ar 2 is an aryl group having 6 to 18 carbon atoms, which 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, and a cyano group, or a heteroaryl group having 4 to 25 carbon atoms, Ar 3 is an aryl group having 6 to 18 carbon atoms, or a heteroaryl group having 4 to 18 carbon atoms, R is an aryl group having 6 to 12 carbon atoms, or a cyano group, n is represented by an integer of 0 to 2. ·Third aspect Ar 1 is an aryl group having 6 to 18 carbon atoms, which may be substituted with a cyano group, or an unsubstituted heteroaryl group having 4 to 18 carbon atoms, Ar 2 is This represents an aryl group with 6 to 18 carbon atoms that may be substituted with a cyano group, or an unsubstituted heteroaryl group with 4 to 18 carbon atoms. Ar 3 teeth, This represents an aryl group with 6 to 18 carbon atoms, or a heteroaryl group with 4 to 18 carbon atoms. R is This represents an aryl group or cyano group with 6 to 12 carbon atoms. n is an integer between 0 and 1. • Fourth aspect Ar 1 teeth, This represents an aryl group with 6 to 18 carbon atoms that may be substituted with a cyano group, or an unsubstituted heteroaryl group with 4 to 18 carbon atoms. Ar 2 teeth, This represents an aryl group with 6 to 18 carbon atoms that may be substituted with a cyano group, or an unsubstituted heteroaryl group with 4 to 18 carbon atoms. Ar 3 teeth, This represents an aryl group with 6 to 18 carbon atoms, or a heteroaryl group with 4 to 18 carbon atoms. R is This represents aryl groups and cyano groups with 6 to 12 carbon atoms. n is 0. • Fifth aspect Ar 1 teeth, It may be substituted with a cyano group. Phenyl group, 1-naphthyl group, 2-naphthyl group, 2-biphenylyl group, 3-biphenylyl group, 4-biphenylyl group, 2-phenantrenyl group, 3-phenantrenyl group, 9-phenantrenyl group, 9-anthracenyl group, p-terphenyl group, or 2-triphenylenyl group, or Unsubstituted, 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-9,9'-[9H]xanthene The group is either a ]-3-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-4-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-1'-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-2'-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-3'-yl group, or a spiro[9H-fluoren-9,9'-[9H]xanthene]-4'-yl group. Ar 2 teeth, It may be substituted with a cyano group. Phenyl group, 2-cyanophenyl group, 3-cyanophenyl group, 4-cyanophenyl group, 1-naphthyl group, 2-naphthyl group, 2-biphenylyl group, 3-biphenylyl group, 4-biphenylyl group, 2-phenantrenyl group, 3-phenantrenyl group, 9-phenantrenyl group, 9-anthracenyl group, p-terphenyl group, or 2-triphenylenyl group, or Unsubstituted, 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-9,9'-[9H]xanthene The group is either a ]-3-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-4-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-1'-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-2'-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-3'-yl group, or a spiro[9H-fluoren-9,9'-[9H]xanthene]-4'-yl group. Ar 3 teeth, Unsubstituted, The phenyl group, 1-naphthyl group, 2-naphthyl group, 2-biphenylyl group, 3-biphenylyl group, 4-biphenylyl group, 2-phenantrenyl group, 3-phenantrenyl group, 9-phenantrenyl group, 9-anthracenyl group, p-terphenyl group, and 2-triphenylenyl group are either 1-dibenzofuranyl group, 2-dibenzofuranyl group, 3-dibenzofuranyl group, 4-dibenzofuranyl group, 1-dibenzothienyl group, 2-dibenzothienyl group, 3-dibenzothienyl group, or 4-dibenzothienyl group. • Sixth aspect Ar 1 teeth, It may be substituted with a cyano group. Phenyl group, 1-naphthyl group, 2-naphthyl group, 2-biphenylyl group, 3-biphenylyl group, or 4-biphenylyl group, or Unsubstituted, It is a 1-dibenzofuranyl group, a 2-dibenzofuranyl group, a 3-dibenzofuranyl group, a 4-dibenzofuranyl group, a 1-dibenzothienyl group, a 2-dibenzothienyl group, a 3-dibenzothienyl group, or a 4-dibenzothienyl group. Ar 2 teeth, It may be substituted with a cyano group. Phenyl group, 1-naphthyl group, 2-naphthyl group, 2-biphenylyl group, 3-biphenylyl group, or 4-biphenylyl group, or Unsubstituted, It is a 1-dibenzofuranyl group, a 2-dibenzofuranyl group, a 3-dibenzofuranyl group, a 4-dibenzofuranyl group, a 1-dibenzothienyl group, a 2-dibenzothienyl group, a 3-dibenzothienyl group, or a 4-dibenzothienyl group. Ar 3 teeth, These are phenyl groups, 1-naphthyl groups, 2-naphthyl groups, 2-biphenylyl groups, 3-biphenylyl groups, or 4-biphenylyl groups. • Seventh aspect Ar 1 teeth, Unsubstituted, The group is a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-biphenylyl group, a 3-biphenylyl group, or a 4-biphenylyl group. Ar 2 teeth, Unsubstituted, The group is a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-biphenylyl group, a 3-biphenylyl group, or a 4-biphenylyl group. Ar 3 teeth, A cyclic azine compound according to any one of claims 1 to 4, wherein the compound is a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-biphenylyl group, a 3-biphenylyl group, or a 4-biphenylyl group.

[0024] Hereinafter, the cyclic azine compound represented by formula (1) may be referred to as cyclic azine compound (1). Preferred specific examples of substituents in cyclic azine compound (1) are as follows.

[0025] Ar 1 teeth, Hydrogen atom, or, It is preferable that the group is an unsubstituted aryl group having 6 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms substituted with a cyano group, or an unsubstituted heteroaryl group having 4 to 25 carbon atoms.

[0026] Ar 2 Preferably, this is an unsubstituted aryl group having 6 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms substituted with a cyano group, or an unsubstituted heteroaryl group having 4 to 25 carbon atoms.

[0027] Ar 1 , and Ar 2 In this compound, the aryl group having 6 to 18 carbon atoms is preferably a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-biphenylyl group, a 3-biphenylyl group, a 4-biphenylyl group, a 2-phenantrenyl group, a 3-phenantrenyl group, a 9-phenantrenyl group, a 9-anthracenyl group, a p-terphenyl group, or a 2-triphenylenyl group. These groups may be substituted with a cyano group, and are particularly preferably unsubstituted or cyano-substituted phenyl, 2-naphthyl, 2-biphenylyl, or 4-biphenylyl groups.

[0028] Ar 1 , and Ar 2In this, the heteroaryl groups having 4 to 25 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-9,9'-[ It is preferable that the group is a 9H]xanthene]-3-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-4-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-1'-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-2'-yl group, a spiro[9H-fluoren-9,9'-[9H]xanthene]-3'-yl group, or a spiro[9H-fluoren-9,9'-[9H]xanthene]-4'-yl group.

[0029] Ar 3 It is preferable that this is an unsubstituted aryl group having 6 to 18 carbon atoms, or an unsubstituted heteroaryl group having 4 to 12 carbon atoms.

[0030] Ar 3 In this compound, the aryl group having 6 to 18 carbon atoms is preferably a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-biphenylyl group, a 3-biphenylyl group, a 4-biphenylyl group, a 2-phenantrenyl group, a 3-phenantrenyl group, a 9-phenantrenyl group, a 9-anthracenyl group, a p-terphenyl group, or a 2-triphenylenyl group. It is particularly preferably a phenyl group, a 2-naphthyl group, a 2-biphenylyl group, or a 4-biphenylyl group.

[0031] Ar 3 In this compound, the heteroaryl group having 4 to 12 carbon atoms is preferably a 1-dibenzofuranyl group, a 2-dibenzofuranyl group, a 3-dibenzofuranyl group, a 4-dibenzofuranyl group, a 1-dibenzothienyl group, a 2-dibenzothienyl group, a 3-dibenzothienyl group, or a 4-dibenzothienyl group.

[0032] R is Aryl groups with 6 to 12 carbon atoms, Alkyl alkyl groups having 1 to 12 carbon atoms, Cycloalkyl groups having 3 to 20 carbon atoms, Cyano group, diarylboryl group, or This represents a diarylphosphine oxide group.

[0033] R is preferably an aryl group or cyano group having 6 to 12 carbon atoms, but is particularly preferred to be an aryl group having 1 to 12 carbon atoms in terms of its excellent electron transport material properties.

[0034] n represents an integer between 0 and 2, but it is preferable that n is 0 or 1. [Specific examples of cyclic azine compounds (1)] Among the cyclic azine compounds according to one aspect of the present invention represented by formula (1), particularly preferred specific examples include (1-1) to (1-138) below, but the cyclic azine compounds according to one aspect of the present invention are not limited to these.

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

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[0042] [ka]

[0043] [ka]

[0044] [ka]

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[0047] [ka]

[0048] The following describes the uses of the cyclic azine compound (1). <Materials for organic electroluminescent devices, electron transport materials for organic electroluminescent devices> The cyclic azine compound (1) is not particularly limited, but can be used, for example, as a material for organic electroluminescent devices. Furthermore, the cyclic azine compound (1) can be used, for example, as an electron transport material for organic electroluminescent devices.

[0049] In other words, the material for an organic electroluminescent device according to one aspect of the present invention includes a cyclic azine compound (1). Furthermore, the electron transport material for an organic electroluminescent device according to one aspect of the present invention also includes a cyclic azine compound (1). The material for an organic electroluminescent device and the electron transport material for an organic electroluminescent device containing a cyclic azine compound (1) contribute to the fabrication of organic electroluminescent devices with excellent drive voltage characteristics and current efficiency. <Organic electroluminescent element> An organic electroluminescent device according to one aspect of the present invention comprises a cyclic azine compound (1).

[0050] 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 cyclic azine compound according to one aspect of the present invention.

[0051] 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.

[0052] 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 cyclic azine compound represented by formula (1)] The organic electroluminescent device contains a cyclic azine 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 a cyclic azine 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 a cyclic azine compound (1). Note that the cyclic azine 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 a cyclic azine compound (1).

[0053] In the following description, we will explain an organic electroluminescent device 100 in which the electron transport layer 7 contains a cyclic azine 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.

[0054] 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).

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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).

[0064] 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.

[0065] 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.

[0066] 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).

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] Examples of phosphorescent dopants include organometallic complexes of transition metals such as iridium, platinum, palladium, and osmium.

[0073] 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))).

[0074] 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.

[0075] 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.

[0076] 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.

[0077] As mentioned above, the electron transport layer preferably contains a cyclic azine compound represented by formula (1) above.

[0078] Furthermore, the electron transport layer may also contain conventionally known electron transport materials in addition to the cyclic azine 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).

[0079] 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.

[0080] 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 cyclic azine compound (1). [Cathode 8] A cathode 8 is provided on the electron transport layer 7.

[0081] 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.

[0082] 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.

[0083] 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).

[0084] 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.

[0085] 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.

[0086] The film thickness of the anode and cathode is preferably 1 μm or less, and more preferably 10 nm to 200 nm.

[0087] 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.

[0088] Furthermore, a cyclic azine compound (1) according to one aspect of the present invention can be synthesized by appropriately combining known reactions (for example, the Suzuki-Miyaura cross-coupling reaction). [Examples]

[0089] 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.

[0090] 1 1H-NMR measurements were performed using Gemini200 (Varian).

[0091] The glass transition temperature was measured using a DSC7020 (manufactured by Hitachi High-Tech Science Corporation).

[0092] 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.).

[0093] Synthesis Example 1: Synthesis of Compounds (1-6)

[0094] [ka]

[0095] Under a nitrogen stream, tetrahydrofuran (70 mL) was added to a flask containing 2,4-bis([1,1'-biphenyl]-4-yl)-6-(4-chloro-1-naphthalenyl)-1,3,5-triazine (3.46 g, 6.33 mmol), 2-[1,1'-biphenyl]-2-yl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (2.13 g, 7.60 mmol), palladium acetate (28 mg, 0.13 mmol), and 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (X-Phos) (121 mg, 0.25 mmol). Further, 2M potassium carbonate aqueous solution (9.5 mL, 19.0 mmol) was added, and the mixture was stirred at 70°C for 17 hours. After cooling to room temperature, water and toluene were added to the reaction mixture and liquid-liquid-liquid was performed. The organic layer was dehydrated with magnesium sulfate and then passed through a silica gel short-pass column (hexane / toluene = 3 / 1). After removing the solvent under reduced pressure, heptane was added and the mixture was heated and stirred. The precipitated material was collected by suction filtration. The resulting solid was washed with ethyl acetate at reflux temperature and then recrystallized from a toluene solution to obtain a white solid of compound (1-6) (yield 2.9 g, yield 69%).

[0096] The glass transition temperature of compounds (1-6) was 123°C.

[0097] 1H-NMR(CDCl3)δ(ppm):9.24(d,J=8.8Hz,1H),8.86(d,J=8.0Hz,4H),8.46(d,J=6.8Hz,1H),7.86(d,J=8.8H z,1H),7.82(d,J=8.0Hz,4H),7.73-7.71(m,4H),7.64-7.38(m,13H),7.18-7.15(m,2H),7.09-7.11(m,3H). Synthesis Example 2: Synthesis of Compound (1-67)

[0098] [ka]

[0099] Under an argon stream, 31 mL of tetrahydrofuran was added to a flask containing 2-([1,1'-biphenyl]-4-yl)-4-chloro-6-phenyl-1,3,5-triazine (1.06 g, 3.09 mmol), 2-[6-[1-(2-naphthalenyl)phenyl]]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.55 g, 3.40 mmol), and tetrakis(triphenylphosphine)palladium (71.4 mg, 0.0618 mmol). 4.6 mL of 2 M aqueous potassium phosphate solution was then added, and the mixture was stirred at 70°C for 21 hours. After cooling to room temperature, water and toluene were added to the reaction mixture for liquid-liquid separation. The organic layer was dehydrated with magnesium sulfate, and the solvent was removed under reduced pressure. The obtained solid was dissolved in toluene (90 ml), activated carbon (0.3 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 solvent was removed by reduced pressure distillation. Recrystallization with toluene and heptane yielded a white solid of compound (1-67) (yield 1.7 g, yield 86%).

[0100] The glass transition temperature of compound (1-67) was 123°C. 1H-NMR(CDCl3)δ(ppm):9.12(s,1H),8.77-8.85(m,5H),8.72(d,J=9.6Hz,1H),7.78(dd,J=1.6Hz,8.0Hz,1H),7.76-7.84 (m,7H),7.66-7.72(m,3H),8.72(d,J=10.4Hz,3H),7.40-7.54(m,6H),7.25-7.30(m,3H),7.11(dd,J=2.0Hz,8.6Hz,1H). Synthesis Example 3: Synthesis of Compound (1-73)

[0101] [ka]

[0102] Under an argon stream, tetrahydrofuran (31 mL) was added to a flask containing 2-([1,1'-biphenyl]-4-yl)-4-chloro-6-phenyl-1,3,5-triazine (2.50 g, 7.27 mmol), 2-[6-[2-(2-naphthalenyl)phenyl]]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (3.48 g, 7.64 mmol), and tetrakis(triphenylphosphine)palladium (252 mg, 0.21 mmol). Further, 2M aqueous potassium phosphate (10.9 mL, 21.8 mmol) was added, and the mixture was stirred at 70°C for 18 hours. After cooling to room temperature, water and toluene were added to the reaction mixture and liquid-liquid-liquid was performed. The organic layer was dehydrated with magnesium sulfate, and the solvent was removed by distillation under reduced pressure. The obtained solid was dissolved in toluene (120 ml), activated carbon (1.3 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 through a Kiriyama funnel lined with Celite, and the solvent was removed by reduced pressure distillation. Recrystallization with toluene and heptane yielded a white solid of compound (1-73) (yield 1.3 g, yield 28%). The glass transition temperature of compound (1-73) was 114°C.

[0103] 1H-NMR(CDCl3)δ(ppm):9.23(s,1H),8.87(d,J=8.4Hz,2H),8.77-8.84(m,3H),7.92-7.94(m,2H),7.71-7.84(m,7H),7 .92-7.94(m,2H),7.49-7.66(m,9H),7.42-7.45(m,3H),7.24(dd,J=2.4Hz,9.2Hz,1H),7.18(dd,J=1.2Hz,8.0Hz,1H). 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.

[0104] 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 a 20 nm film of sublimation-purified 3-(10-phenyl-9-anthryl)-dibenzofuran and 2,7-bis[N,N-di-(4-tertbutylphenyl)]amino-bisbenzofuran-9,9'-spirofluorene in a 95:5 (mass ratio). 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 compounds (1-6) synthesized in Synthesis Example-1 and Liq were deposited in a 50:50 (mass ratio) ratio at a density of 25 nm to fabricate 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.

[0105] 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).

[0106] 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).

[0107] 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) and drive voltage (V) were measured when the current was flowing. Note that the current efficiency and drive voltage are relative values, with the results from Reference Example 1 of the element described later set as the baseline value (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 (1-67) was used instead of compound (1-6). The obtained measurement results are shown in Table 1. Element Example-3 An organic electroluminescent device was fabricated and evaluated using the same method as in Element Example-1, except that compound (1-73) was used instead of compound (1-6). The obtained measurement results are shown in Table 1. Element Reference Example - 1 An organic electroluminescent device was fabricated and evaluated using the same method as in Element Example-1, except that compound (ETL-1) described in Patent Document 2 was used instead of compound (1-6). The obtained measurement results are shown in Table 1.

[0108] [ka]

[0109] [Table 1]

[0110] The cyclic azine 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]

[0111] 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. Cyclic azine compound represented by formula (1): 【Chemistry 1】 In formula (1), Ar １ teeth, Hydrogen atom, or, Represents a phenyl group, a 1-naphthyl group, a 2-biphenylyl group, a 3-biphenylyl group, or a 4-biphenylyl group, which may be substituted with an alkyl group having 1 to 12 carbon atoms. Ar ２ teeth, Represents a phenyl group, 1-naphthyl group, 2-naphthyl group, 2-biphenylyl group, 3-biphenylyl group, or 4-biphenylyl group, which may be substituted with an alkyl group having 1 to 12 carbon atoms. Ar ３ teeth, Represents a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-biphenylyl group, a 3-biphenylyl group, or a 4-biphenylyl group. R is, Aryl groups having 6 to 12 carbon atoms, Alkyl alkyl groups having 1 to 12 carbon atoms, Cycloalkyl groups having 3 to 20 carbon atoms, Cyano group, diarylboryl group, or Represents a phosphine oxide group, n represents 0, Np represents one of the bases selected from formulas (2-1), (2-2), and (2-3). 【Chemistry 2】

2. Ar １ teeth, Hydrogen atom, or, Represents a phenyl group which may be substituted with an alkyl group having 1 to 12 carbon atoms. Ar ２ teeth, Represents a phenyl group, a 2-biphenylyl group, a 3-biphenylyl group, or a 4-biphenylyl group, which may be substituted with an alkyl group having 1 to 12 carbon atoms. Ar ３ teeth, The cyclic azine compound according to claim 1, wherein the compound is a phenyl group, a 1-naphthyl group, or a 2-naphthyl group.

3. Ar １ teeth, Represents a hydrogen atom or a phenyl group, Ar ２ teeth, Represents a phenyl group, a 2-biphenylyl group, a 3-biphenylyl group, or a 4-biphenylyl group. Ar ３ is Represents a phenyl group, a 1-naphthyl group, or a 2-naphthyl group, The cyclic azine compound according to claim 1, wherein Np is one group selected from formulas (2-1) and (2-2).

4. A material for an organic electroluminescent device comprising a cyclic azine compound according to any one of claims 1 to 3.

5. An electron transport material for an organic electroluminescent device comprising a cyclic azine compound according to any one of claims 1 to 3.

6. An organic electroluminescent device comprising a cyclic azine compound according to any one of claims 1 to 3.

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