Pyrimidine compounds, materials for organic electroluminescent devices, and organic electroluminescent devices.

Abstract

To provide a novel pyrimidine compound that facilitates the manufacture of an organic electroluminescent element with reduced driving voltage and increased current efficiency, and also provide a material for organic electroluminescent elements and an organic electroluminescent element each of which includes the pyrimidine compound.SOLUTION: The present invention provides a pyrimidine compound of a specific structure represented by formula (1), and a material for organic electroluminescent elements and an organic electroluminescent element each of which includes the pyrimidine compound.SELECTED DRAWING: Figure 2

Description

[[Technical Field]]

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

[0002] Practical application of organic electroluminescent devices has begun, mainly for small mobile applications. However, performance improvement is essential for further expansion of applications, and materials having high current efficiency, low driving voltage, high luminous efficiency characteristics and long lifespan characteristics are required. Patent Documents 1 and 2 disclose pyrimidine compounds, which are materials for organic electroluminescent devices. [[Prior Art Literature]] [[Patent Literature]]

[0003] [[Patent Document 1]] Korean Unexamined Patent Publication No. 2017 / 0093023 [[Patent Document 2]] Korean Unexamined Patent Publication No. 2017 / 0113397 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] However, it cannot be said that the pyrimidine compounds according to Patent Documents 1 and 2 sufficiently satisfy driving voltage characteristics.

[0005] Therefore, one aspect of the present invention is directed to providing a novel pyrimidine compound that contributes to forming an organic electroluminescent device capable of reducing driving voltage and improving current efficiency.

[0006] Furthermore, another aspect of the present invention is directed to providing an organic electroluminescent device with reduced driving voltage and improved current efficiency. [[Means for Solving the Problem]]

[0007] One aspect of the present invention is as follows. 1. A pyrimidine compound represented by formula (1):

[0008]

Chemical Formula

[0009] In the formula: X 1 and X 2 one of either is a nitrogen atom and the other is C-H; Ar 1 and Ar 2 each independently represents a phenyl group, a biphenylyl group, or a naphthyl group; Ar 3 and Ar 4 each independently an aryl group having 6 to 20 carbon atoms, or represents a heteroaryl group having 4 to 20 carbon atoms; L 1 and L 2 each independently represents a direct bond, phenylene, pyridylene, or naphthylene; Ring A is pyridine which may optionally have one or more substituents selected from the group consisting of a phenyl group, a pyridyl group, a naphthyl group, an alkyl group having 1 to 10 carbon atoms, and a CN group, and Ar 3 and L 1 are each bonded to two adjacent carbon atoms of the pyridine ring; n is 1 or 2; when n is 2, the two L 1 may be the same as or different from each other. 2. The pyrimidine compound according to 1., wherein Ar 1 and Ar 2 are identical. 3. The pyrimidine compound according to 1. or 2., wherein at least one of Ar 1 and Ar 2 is a 4-biphenylyl group. 4. A pyrimidine compound represented by formulas (E1) to (E10), as described in any of 1 to 3.

[0010] [ka]

[0011] 5. Anode and, Cathode and, It comprises one or more organic thin film layers including at least an emissive layer, At least one layer of the organic thin film layer contains the pyrimidine compound described in any of 1 to 4. [Effects of the Invention]

[0012] According to one aspect of the present invention, a novel pyrimidine compound can be provided that contributes to the formation of an organic electroluminescent element that can reduce the driving voltage and improve current efficiency.

[0013] Furthermore, according to another aspect of the present invention, a material for an organic electroluminescent device containing the pyrimidine compound and an electron transport material for an organic electroluminescent device can be provided. Moreover, according to yet another aspect of the present invention, an organic electroluminescent device with a reduced driving voltage can be provided. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic cross-sectional view showing an example of a stacked configuration of an organic electroluminescent element according to one aspect of the present disclosure. [Figure 2] This is a schematic cross-sectional view showing an example of another stacked configuration of an organic electroluminescent element according to one aspect of the present disclosure (configuration of element example-1). [Modes for carrying out the invention]

[0015] The following describes in detail each aspect of the present invention.

[0016] A pyrimidine compound according to one aspect of the present invention is a pyrimidine compound represented by formula (1).

[0017] [ka]

[0018] During the ceremony, X 1 and X 2 In this case, one of the atoms is a nitrogen atom, and the other is CH; Ar 1 and Ar 2 Each of them operates independently. Represents a phenyl group, a biphenylyl group, or a naphthyl group; Ar 3 and Ar 4 Each of them operates independently. An aryl group having 6 to 20 carbon atoms, or Represents a heteroaryl group with 4 to 20 carbon atoms; L 1 and L 2 Each of them operates independently. Represents a direct bond, phenylene, pyridylene, or naphthylene; Ring A is, A pyridine which may have one or more substituents consisting of a phenyl group, a pyridyl group, a naphthyl group, an alkyl group having 1 to 10 carbon atoms, and a CN group, Ar 3 and L 1 Each of these is bonded to two adjacent carbon atoms of the pyridine ring; n is either 1 or 2; When n is 2, two L 1 These may be identical or different from one another. [Ar 1 and Ar 2 [About] Ar 1 and Ar 2 These are, independently, a phenyl group, a biphenylyl group, or a naphthyl group.

[0019] Ar 1 and Ar2 The group is preferably a biphenylyl group or a naphthyl group, and more preferably a 4-biphenylyl group.

[0020] Ar 1 and Ar 2 It is preferable that they are the same. [Ar 3 and Ar 4 [About] Ar 3 and Ar 4 Each of these is independently an aryl group having 6 to 20 carbon atoms, or a heteroaryl group having 4 to 20 carbon atoms.

[0021] Specific examples of aryl groups having 6 to 20 carbon atoms include phenyl, naphthyl, phenanthryl, anthonyl, pyrenyl, pyranyl, fluorenyl, dimethylfluorenyl, triphenylenyl, fluoranthenyl, and chrysenyl groups.

[0022] Specific examples of heteroaryl groups with 4 to 20 carbon atoms include pyridyl, pyrimidyl, pyrazyl, quinolyl, isoquinolyl, nadithyridinyl, and acridinyl groups.

[0023] Ar 3 and Ar 4 The group is preferably a phenyl group, a naphthyl group, a phenanthryl group, or a pyridyl group. [Regarding Ring A] Ring A is, A pyridine which may have one or more substituents consisting of a phenyl group, a pyridyl group, a naphthyl group, an alkyl group having 1 to 10 carbon atoms, and a CN group, Ar 3 and L 1 Each of these is bonded to two adjacent carbon atoms on the pyridine ring.

[0024] Ring A is specifically represented by equations (A-1) and (A-2).

[0025] [ka]

[0026] In equations (A-1) and (A-2), the dashed lines represent Ar independently. 3 or L 1 This indicates the position where substitution occurs. The pyridine ring is Ar 3 and L 1 In addition, the group may be substituted with one or more groups selected from the group consisting of phenyl groups, pyridyl groups, naphthyl groups, C1-C10 alkyl groups, and CN groups. Of these, phenyl groups, pyridyl groups, naphthyl groups, C1-C5 alkyl groups, and CN groups are preferred, phenyl groups, pyridyl groups, naphthyl groups, and C1-C5 alkyl groups are more preferred, phenyl groups, pyridyl groups, naphthyl groups, and methyl groups are even more preferred, and phenyl groups, pyridyl groups, and methyl groups are particularly preferred. [L 1 and L 2 [About] L 1 and L 2 These represent, independently, direct bond, phenylene, pyridylene, and naphthylene. 1 and L 2 Preferably, each of these is directly bonded, phenylene, and pyridylene, respectively. [X 1 and X 2 [About] X 1 and X 2 In this case, one of the atoms is a nitrogen atom, and the other is CH.

[0027] The following are specific examples of pyrimidine compounds. However, the present invention is not limited to these examples.

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[0067] Furthermore, from the viewpoint of reducing the drive voltage, the structure shown below is preferred.

[0068] [ka]

[0069] Pyrimidine compounds can be used, for example, in organic electronic devices such as organic electroluminescent devices and photoelectric elements. <Materials for organic electroluminescent devices> A material for an organic electroluminescent device according to one aspect of the present invention contains the above-mentioned pyrimidine compound. The pyrimidine compound can be used, for example, as an electron transport material for an organic electroluminescent device.

[0070] The structural reasons why a pyrimidine compound according to one aspect of the present invention exhibits a low driving voltage, for example, as an electron transport material for an organic electroluminescent device, are presumed to be as follows. <Structural reasons for low drive voltage> The triazine ring incorporates three highly electronegative nitrogen atoms into its ring structure, thereby increasing the electron affinity of the ring itself and resulting in high electron transport properties. Furthermore, attempts have been made to enhance electron injection from the cathode by incorporating a pyridine ring within the triazine compound molecule.

[0071] However, the high electron affinity of the triazine ring can inhibit electron injection into commonly used luminescent and hole-blocking layers. Furthermore, the pyridine ring can further increase the electron affinity of the molecule, thus inhibiting electron injection into luminescent and hole-blocking layers.

[0072] On the other hand, although the pyrimidine ring contains multiple nitrogen atoms, similar to the triazine ring, the number of nitrogen atoms is smaller than that of the triazine ring, resulting in lower electron affinity, which promotes electron injection into the light-emitting layer or hole-blocking layer. Furthermore, the pyrimidine compound according to this embodiment has Ar and L atoms on the carbon adjacent to the pyridine ring. 1 The bonding of these rings increases the dihedral angle between the pyridine ring and the adjacent aromatic ring, suppressing the increase in the molecule's electron affinity. This allows for increased electron injection from the cathode while maintaining a low electron affinity. This enhanced electron injection results in high current efficiency.

[0073] On the other hand, unlike triazine rings, pyrimidine rings themselves possess a large dipole moment. In organic thin films, it is known that when organic molecules have a dipole moment, the organic molecules spontaneously orient themselves, resulting in a film with an order similar to a crystalline structure. Highly crystalline films can generate defects within the film, hindering charge transport; therefore, high amorphousness is generally required for organic films used in organic electroluminescent devices.

[0074] Furthermore, the spontaneous orientation of organic molecules increases the sublimation temperature. This accelerates thermal decomposition during the fabrication of organic electroluminescent devices, which in turn affects the durability of the organic electroluminescent devices due to the inclusion of decomposition products.

[0075] In other words, compounds containing a pyrimidine ring can promote electron injection into the luminescent layer or hole blocking layer, but they have the drawback of suppressing electron transport within the film.

[0076] In contrast, a pyrimidine compound according to one aspect of the present invention is Ar in formula (1). 3 Because ring A forms high steric hindrance, spontaneous orientation of the molecule is suppressed, making it possible to have high amorphous properties. Therefore, one embodiment of the present invention, a pyrimidine compound, promotes electron injection into the hole blocking layer without suppressing electron transport in the film, and thus makes it possible to reduce the driving voltage.

[0077] Furthermore, since the pyrimidine compound according to one aspect of the present invention also contributes to lowering the sublimation temperature, it can also contribute to suppressing the thermal decomposition of materials and the reduction in the durability of organic electroluminescent devices.

[0078] [ka]

[0079] <Organic electroluminescent element> Hereinafter, an organic electroluminescent element according to one aspect of the present invention (hereinafter sometimes simply referred to as an organic electroluminescent element) will be described.

[0080] An organic electroluminescent element according to one aspect of the present invention contains a pyrimidine compound.

[0081] 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.

[0082] (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 / Hole Transport Layer / Electron Blocking Layer / Emitting Layer / Hole Blocking Layer / Electron Transport Layer / Electron Injection Layer / Cathode The pyrimidine compound may be included in any of the above layers, but it is preferable that it be included in one or more layers selected from the group consisting of the light-emitting layer and the layer between the light-emitting layer and the cathode, in order to have excellent light-emitting properties for the organic electroluminescent element. Therefore, in the configuration shown in (i) to (vi) above, it is preferable that the pyrimidine compound is included in one or more layers selected from the group consisting of the light-emitting layer, hole blocking layer, electron transport layer and electron injection layer.

[0083] 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 (v) above as an example.

[0084] Although the organic electroluminescent element shown in Figure 1 has a so-called bottom-emission type element configuration, 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 other known element configurations, such as a top-emission type.

[0085] Figure 1 is a schematic cross-sectional view showing an example of a stacked configuration of an organic electroluminescent element according to one aspect of the present invention.

[0086] The organic electroluminescent element 100 comprises a substrate 1, an anode 2, a hole injection layer 3, a hole transport layer 4, a light-emitting layer 5, an electron transport layer 6, an electron injection 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, a hole blocking layer may be provided between the light-emitting layer 5 and the electron transport layer 6, or the hole injection layer 3 may be omitted and the hole transport layer 4 may be directly provided on the anode 2.

[0087] Furthermore, the configuration may include a single layer that combines the functions of multiple layers, such as an electron injection / transport layer that combines the functions of both an electron injection layer and an electron transport layer, instead of the multiple layers themselves. In addition, for example, the single-layer hole transport layer 4 and the single-layer electron transport layer 6 may each consist of multiple layers. <Layer containing pyrimidine compounds> In the configuration example shown in Figure 1, the organic electroluminescent element 100 contains the pyrimidine compound in one or more layers selected from the group consisting of an emissive layer 5, an electron transport layer 6, and an electron injection layer 7. In particular, it is preferable that the electron transport layer 6 contains the pyrimidine compound. The pyrimidine compound may be included in multiple layers of the organic electroluminescent element.

[0088] In the following, we will describe an organic electroluminescent element 100 in which the electron transport layer 6 contains a pyrimidine compound. [Circuit board 1] There are no particular limitations on substrate 1; any substrate that can be used in a typical organic electroluminescent device can be used. Examples include glass plates, quartz plates, and plastic plates. [Anode 2] An anode 2 is provided on substrate 1 (on the side of hole injection layer 3).

[0089] For the anode material, compounds that can be used in ordinary organic electroluminescent devices can be used. Examples include metals, alloys, electrically conductive compounds, and mixtures thereof with high work functions (e.g., 4 eV or more). Specific examples of anode materials include metals such as Au; and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO2, and ZnO. [Hole injection layer 3, hole transport layer 4] Between the anode 2 and the light-emitting layer 5 (described later), a hole injection layer 3 and a hole transport layer 4 are provided in that order, starting from the anode 2 side.

[0090] 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 organic or inorganic, and compounds that can be used in ordinary organic electroluminescent devices can be used.

[0091] The hole injection layer and hole transport layer may be a single structure consisting of one or more materials, or a laminated structure consisting of multiple layers of the same or different compositions.

[0092] The hole transport layer 4 may be a stacked structure of two or more layers, and from the anode 2 side, it may be provided in the order of a first hole transport layer 41 and a second hole transport layer 42, and this second hole transport layer 42 can be used as an electron blocking layer in the configuration of (vi) above. [Luminous layer 5] A light-emitting layer 5 is provided between the hole transport layer 4 and the electron transport layer 6, which will be described later.

[0093] As the material for the light-emitting layer, any light-emitting material that can be used in a typical organic electroluminescent device can be used. Examples include phosphorescent materials, fluorescent materials, and thermally activated delayed fluorescence materials.

[0094] 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. The luminescence primarily arises from the dopant and can have any color.

[0095] 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 4 or electron transport layer 6). This can further increase the luminescence efficiency of the organic electroluminescent device.

[0096] 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 6] An electron transport layer 6 is provided between the light-emitting layer 5 and the electron injection layer 7, which will be described later.

[0097] The electron transport layer preferably contains a pyrimidine compound. Furthermore, the electron transport layer may also contain one or more conventionally known electron transport materials in addition to the pyrimidine compound.

[0098] Furthermore, if the pyrimidine compound is not included in the electron transport layer but is included in another layer, one or more conventionally known electron transport materials can be used as the electron transport material constituting the electron transport layer.

[0099] Conventionally known electron transport materials include alkali metal complexes, alkaline earth metal complexes, and earth metal complexes. Examples of alkali metal complexes, alkaline earth metal complexes, and earth metal complexes 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, and tris(8-hydroxyquinolinate). Examples include 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, bis(2-methyl-8-quinolinate)-1-naphtholatealuminum, and bis(2-methyl-8-quinolinate)-2-naphtholategallium.

[0100] 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.

[0101] In the organic electroluminescent element according to this embodiment, an electron injection layer may be provided for the purpose of improving electron injection properties and enhancing element characteristics (for example, luminous efficiency, low voltage drive, or high durability).

[0102] The electron transport layer 6 may have a stacked structure of two or more layers, and from the light-emitting layer 5 side, it is provided in the order of a first electron transport layer 61 and a second electron transport layer 62, and this first electron transport layer 61 can be used as a hole blocking layer in the configuration of (vi) above.

[0103] The pyrimidine compound according to one embodiment of the present invention can be used in both the first electron transport layer and the second electron transport layer, or in either one of them. [Electron injection layer 7] An electron injection layer 7 is provided between the electron transport layer 6 and the cathode 8, which will be described later.

[0104] As the material for the electron injection layer, compounds that can be used in ordinary organic electroluminescent devices can be used. Examples of such organic compounds include fluorenone, anthraquinodimethane, diphenoquinone, thiopyrandioxide, oxazole, oxadiazole, triazole, imidazole, perylenetetracarboxylic acid, fluolenylidenemethane, anthraquinodimethane, and anthrone.

[0105] Furthermore, examples of materials for the electron injection layer include various oxides, fluorides, nitrides, and oxidized nitrides such as SiO2, AlO, SiN, SiON, AlON, GeO, LiO, LiON, TiO, TiON, TaO, TaON, TaN, LiF, C, and Yb. The pyrimidine compounds of the present invention can also be used. [Cathode 8] A cathode 8 is provided on the electron injection layer 7.

[0106] For the cathode material, compounds that can be used in ordinary organic electroluminescent devices can be used. Examples include metals with low work functions (hereinafter also referred to as electron-injection metals), alloys, electrically conductive compounds, and mixtures thereof. Here, a metal with a low work function is, for example, a metal with a work function of 4 eV or less.

[0107] A mixture of an electron-injectable metal and a metal with a higher work function and greater stability, such as a magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al2O3) mixture, or lithium / aluminum mixture is preferred. [Method of forming each layer] Each layer, excluding the electrodes (anode and cathode), as described above, can be formed by thinning using known methods such as vacuum deposition, spin coating, casting, or the LB (Langmuir-Blodgett method). The material for each layer may be used alone, or it may be used together with a binder resin or other material and solvent as needed.

[0108] 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.

[0109] 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.

[0110] The film thickness of the anode and cathode is preferably 1 μm or less, and more preferably 10 nm to 200 nm.

[0111] Furthermore, the layer containing the pyrimidine compound may be formed in combination with the conventionally known electron transport material described above. Therefore, for example, the pyrimidine compound and the conventionally known electron transport material may be co-deposited, or a layer of the conventionally known electron transport material may be laminated on top of the pyrimidine compound layer.

[0112] Organic electroluminescent elements 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 onto a screen, or as a display device that allows direct viewing of still or moving images.

[0113] When using organic electroluminescent elements as a display device for video playback, the driving method may be a simple matrix (passive matrix) method or an active matrix method. Furthermore, by using two or more organic electroluminescent elements with different emission colors, it is possible to create a full-color display device. [Examples]

[0114] The present disclosure will be described in further detail below based on examples, but the present disclosure shall not be construed as being limited in any way by these examples.

[0115] 1 H-NMR spectra were measured using either a Gemini200 (Varian) or a Bruker ASCEND 400 (400 MHz; BRUKER).

[0116] 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.). Synthesis Example 1 (Synthesis of E1)

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[0118] Under an argon atmosphere, 2-(3-bromo-5-chlorophenyl)-4,6-bis(4-biphenylyl)pyrimidine (5.74 g, 10 mmol), phenylboronic acid (1.34 g, 11 mmol), 2M potassium phosphate aqueous solution (16.5 mL), and tetrakis(triphenylphosphine)palladium (231 mg, 0.2 mmol) were suspended in THF (200 mL) and refluxed for 27 hours. The reaction mixture was filtered, and the filtrate was concentrated. The concentrated filtrate was added to methanol to precipitate a solid, which was then filtered to obtain the target 4,6-bis(4-biphenylyl)-2-(5-chlorobiphenyl-3-yl)pyrimidine (yield 5.11 g, yield 90%). Under an argon atmosphere, 4,6-bis(4-biphenylyl)-2-(5-chlorobiphenyl-3-yl)-pyrimidine (2.0 g, 3.5 mmol), 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-phenylpyridine (1.18 g, 4.2 mmol), 2M potassium phosphate aqueous solution (6.3 mL), palladium acetate (15.7 mg, 0.07 mmol), and 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (XPhos, 67 mg, 0.14 mmol) were suspended in THF (35 mL) and refluxed for 17 hours. After cooling, water was added to the reaction mixture, the solid was filtered off, and the mixture was washed with water and methanol to obtain 2-[5-(2-phenylpyridine-3-yl)-biphenyl-3-yl]-4,6-bis(4-biphenylyl)pyrimidine (E1) (yield 2.38 g, yield 99%). 1 H-NMR (400MHz, CDCl3): δ8.88(s,1H),8.77(dd,J=4.8,1.7Hz,1H),8.69(s,1H),8.36(d,J=8.5Hz,4H), 8.12(s,1H),8.00(dd,J=7.7,1.7Hz,1H),7.82(d,J=8.5Hz,4H),7.70-7.72(m,4H),7.30-7.55(m,18H). Synthesis Example 2 (Synthesis of E2)

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[0120] Under an argon atmosphere, 4-(3-bromo-5-chlorophenyl)-2-(4-bromophenyl)-6-(4-biphenylyl)pyrimidine (2.0 g, 3.47 mmol), phenylboronic acid (0.93 g, 7.63 mmol), 2M potassium phosphate aqueous solution (10.4 mL), and tetrakis(triphenylphosphine)palladium (80 mg, 0.069 mmol) were suspended in THF (35 mL) and refluxed for 19 hours. The reaction mixture was filtered, and the filtrate was concentrated. The concentrated filtrate was added to methanol to precipitate a solid, which was then filtered to obtain the target 2,4-bis(4-biphenylyl)-4-(5-chlorobiphenyl-3-yl)pyrimidine (yield 1.91 g, yield 96%). Under an argon atmosphere, 2,4-bis(4-biphenylyl)-4-(5-chlorobiphenyl-3-yl)-pyrimidine (1.81 g, 3.17 mmol), 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-phenylpyridine (0.982 g, 3.49 mmol), 2M potassium phosphate aqueous solution (4.8 mL), palladium acetate (14 mg, 0.063 mmol), and 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (XPhos, 61 mg, 0.127 mmol) were suspended in THF (32 mL) and refluxed for 15 hours. After cooling, water was added to the reaction mixture, the solid was filtered off, and the mixture was washed with water and methanol to obtain 2-[5-(2-phenylpyridine-3-yl)-biphenyl-3-yl]-4,6-bis(4-biphenylyl)pyrimidine (E2) (yield 3.18 g, yield 92%). 1 H-NMR (400MHz, CDCl3): δ8.78(d,J=4.7Hz,1H),8.76(d,J=8.8Hz,2H),8.41(s,1H),8.36(d,J=8.6Hz,2H),8.04(s,1H) ),7.98(d,J=7.7Hz,1H),7.82(d,J=8.6Hz,2H),7.79(d,J=8.6Hz,2H),7.78(s,1H),7.61(s.1H),7.35-7.54(m,17H). Synthesis Example 3 (Synthesis of E9)

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[0122] Under an argon atmosphere, 2-chloro-4,6-bis(4-biphenylyl)pyrimidine (1.40 g, 3.3 mmol), (5,5-dimethyl-1,3,2-dioxaborinan-2-yl)-3,5-bis(2-phenylpyridine-3-yl)benzene (1.99 g, 4.0 mmol), 2M potassium phosphate aqueous solution (5.0 mL), and tetrakis(triphenylphosphine)palladium (77.2 mg, 0.067 mmol) were suspended in THF (17 mL) and refluxed for 5 hours. Water and methanol were added to the reaction mixture, and the mixture was filtered. The filtrate was washed with water and methanol. The resulting solid was recrystallized in toluene to obtain the target 4,6-bis(4-biphenylyl)-2-[3,5-bis(2-phenylpyridine-3-yl)phenyl]pyrimidine (E9) (yield 2.05 g, yield 80%). 1 H-NMR (400MHz, CDCl3): δ8.73(d,J=4.7H,2H),8.47(s,2H),8.23(d,J=8.5Hz,4H),8.05(s,1H),7.79(d,J= 8.5Hz,4H),7.69-7.72(m,4H),7.61(d,J=7.7Hz,2H),7.40-7.53(m,10H),7.27-7.37(m,8H),7.21(s,1H). Synthesis Example 4 (Synthesis of E10)

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[0124] Under an argon atmosphere, 4,6-bis(4-biphenylyl)-2-[3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-5-chlorobiphenyl-3-yl]pyrimidine (2.00 g, 3.0 mmol), 3-chloro-5-methyl-2-phenylpyridine (0.74 g, 3.6 mmol), 2M potassium phosphate aqueous solution (4.5 mL), and bis(tricyclohexylphosphine)palladium dichloride (44.6 mg, 0.06 mmol) were suspended in THF (30 mL) and refluxed for 2 hours. Water and methanol were added to the reaction mixture, and after filtration, the filtrate was washed with water and methanol. The obtained solid was recrystallized in toluene to obtain the target 2-[5-(5-methyl-2-phenylpyridine-3-yl)-biphenyl-3-yl]-4,6-bis(4-biphenylyl)pyrimidine (E10) (yield 1.25 g, yield 59%). 1 H-NMR (400MHz, CDCl3): δ8.82(s,1H),8.66(s,1H),8.60(d,J=2.1Hz,1H),8.36(d,J=6.7Hz,4H),8.12(s ,1H),7.82(d,J=8.5Hz,4H),7.80(d,J=2.1Hz,1H),7.69-7.72(m,4H),7.27-7.53(m,17H),2.50(s,3H). Furthermore, the cyclic azine compounds used in the experimental examples below were synthesized by the same means as those shown in the synthesis examples above.

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[0126] The structural formulas and abbreviations of the compounds used in the fabrication and performance evaluation of organic electroluminescent devices are shown below.

[0127] [ka]

[0128] Element Example 1 (For the stacked configuration of the following organic electroluminescent element, please refer to 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.

[0129] 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 fabricated by depositing sublimation-purified HTL-1 and NDP-9 at a rate of 0.15 nm / second to a thickness of 10 nm. (Preparation of the first hole transport layer 1051) The first hole transport layer 1051 was fabricated by depositing an 85 nm film of sublimation-purified HTL at a rate of 0.15 nm / second. (Preparation of the second hole transport layer 1052) EBL-1, 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) Sublimation-purified BH-1 and BD-1 were deposited in a 95:5 (mass ratio) ratio at a 20 nm thickness to create the light-emitting layer 106. 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 HBL-1 at a rate of 0.05 nm / second. (Fabrication of the second electron transport layer 1072) Compounds E1 and Liq were deposited in a 50:50 (mass ratio) ratio at a 25 nm thickness 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 ytterbium, silver / magnesium (mass ratio 9 / 1), and silver, deposited in that order at 2 nm, 12 nm, and 90 nm, respectively, to form a three-layer structure. The deposition rate for ytterbium was 0.02 nm / second, for silver / magnesium it was 0.5 nm / second, and for silver it was 0.2 nm / second.

[0130] 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).

[0131] 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).

[0132] A DC current was applied to the organic electroluminescent element fabricated as described above, resulting in a current density of 10 mA / cm². 2 The drive voltage (V) and current efficiency were measured when the current was applied. The drive voltage and current efficiency are relative values, with the results from Comparative Example 1 of the element described later set as the baseline value (100). The obtained measurement results are shown in Table 1. (Examples of elements - 2 to 10) In Element Example-1, an organic electroluminescent device was fabricated and evaluated using the same method as in Element Example-1, except that compounds E2 to E10 were used instead of compound E1. The obtained measurement results are shown in Table 1. (Comparative Examples of Components - 1~3) In Element Example-1, an organic electroluminescent device was fabricated and evaluated using the same method as in Element Example-1, except that compounds ETL-1 to ETL-3 were used instead of compound E1. The obtained measurement results are shown in Table 1.

[0133] [Table 1] [Explanation of Symbols]

[0134] 100 Organic Electroluminescent Devices 1 circuit board 2 Anode 3. Hole injection layer 4. Hole transport layer 5. Emitting layer 6 Electron transport layer 7 Electron injection layer 8 cathode 101 circuit board 102 Anode 103 Hole injection layer 1051 First hole transport layer 1052 Second hole transport layer 106 Emitting layer 1071 First electron transport layer 1072 Second electron transport layer 108 Cathode

Claims

1. Pyrimidine compounds represented by formula (1): 【Chemistry 1】 During the ceremony, X １ and X ２ In this case, one of the atoms is a nitrogen atom, and the other is a C-H group; Ar １ and Ar ２ They are the same, Represents a phenyl group, a biphenylyl group, or a naphthyl group; Ar ３ and Ar ４ Each of them operates independently. An aryl group having 6 to 20 carbon atoms, or Represents a heteroaryl group with 4 to 20 carbon atoms; L １ and L ２ Each of them operates independently. Represents a direct bond, phenylene, pyridylene, or naphthylene; Ring A is, A pyridine which may have one or more substituents consisting of a phenyl group, a pyridyl group, a naphthyl group, an alkyl group having 1 to 10 carbon atoms, and a CN group, Ar ３ and L １ are each bonded to two adjacent carbon atoms of the pyridine ring; n is either 1 or 2; When n is 2, two L １ These may be identical or different from one another.

2. Ar １ and Ar ２ The pyrimidine compound according to claim 1, wherein is a 4-biphenylyl group.

3. A pyrimidine compound according to claim 1, represented by formulas (E1) to (E10). 【Chemistry 2】

4. Anode and, Cathode and, It comprises one or more organic thin film layers including at least an emissive layer, An organic electroluminescent element comprising at least one layer of the organic thin film layer containing the pyrimidine compound according to any one of claims 1 to 3.

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