Compound, hole transport material and organic electroluminescent device

Abstract

The invention belongs to the technical field of organic light-emitting display, and particularly relates to a compound, a hole transport material and an organic light-emitting device. The structure of the organic compound is shown as a formula (I), and the organic compound can be used as a hole transport material. The compound has a substituted fluorene structure instead of a parent structure of arylamine, is high in bond energy between atoms, has good thermal stability, is beneficial to solid-state accumulation between molecules, is high in hole transition capability, and can effectively reduce the voltage of a device and prolong the service life of the material when being used as a hole transport material. The invention also provides an organic electroluminescent device and a display device containing the compound shown in the formula (I). # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the technical field of organic light-emitting display, and particularly relates to a compound, a hole transport material, and an organic electroluminescent device. Background Art

[0002] Electroluminescence (EL) refers to the phenomenon that a luminescent material emits light under the action of an electric field, being excited by an electric current and an electric field. It is a luminescence process that directly converts electrical energy into light energy. Organic electroluminescent displays (hereinafter referred to as OLEDs) have a series of advantages such as self-luminescence, low-voltage DC drive, all-solid state, wide viewing angle, light weight, simple composition and process. Compared with liquid crystal displays, organic electroluminescent displays do not require a backlight, have a large viewing angle, low power, a response speed that can reach 1000 times that of liquid crystal displays, and a manufacturing cost lower than that of liquid crystal displays with the same resolution. Therefore, organic electroluminescent devices have very broad application prospects.

[0003] With the continuous advancement of OLED technology in the two major fields of lighting and display, people pay more attention to the research of high-efficiency organic materials that affect the performance of OLED devices. An organic electroluminescent device with good efficiency and long life is usually the result of the optimal combination of the device structure and various organic materials, which provides great opportunities and challenges for chemists to design and develop functional materials with various structures.

[0004] Compared with inorganic luminescent materials, organic electroluminescent materials have many advantages. For example, they have good processability and can form films on any substrate by evaporation or spin coating, enabling flexible display and large-area display; the optical, electrical, and stability properties of the materials can be adjusted by changing the molecular structure, and there is a large space for material selection. In the most common OLED device structure, it usually includes the following types of organic materials: hole injection materials, hole transport materials, electron transport materials, as well as various color-emitting materials (dyes or doped guest materials) and corresponding host materials, etc. Among them, as an important functional material, the hole transport material has a direct impact on the hole mobility and ultimately affects the luminous efficiency of the OLED. However, the hole transport rate that can be achieved by the hole transport materials currently used in OLEDs is relatively low, the energy level matching with the adjacent layer is poor, and the efficiency and life cannot be taken into account at the same time, seriously restricting the display function and development of OLED display devices. Summary of the Invention

[0005] The purpose of the present invention is to provide a compound, a hole transport material, and an organic electroluminescent device to improve the working efficiency and extend the service life of the organic electroluminescent device.

[0006] The object of the first aspect of the present invention is to provide a compound having a structure as shown in formula (I):

[0007]

[0008] Wherein, R 1 -R 2 are independently selected from aromatic groups of C6-C 30 or heteroaryl groups of C3-C 30 , and at least one is selected from aromatic or heteroaryl groups of C 12 -C 20 , and R 1 , R 2 can be connected to form a ring;

[0009] R 3 -R 7 are independently selected from hydrogen, deuterium, C1-C4 alkanes, C5-C 10 cycloalkanes, aromatic groups of C6-C 30 , heteroaryl groups of C3-C 30 , and adjacent substituents can be connected to form a ring;

[0010] R 8 -R 9 are independently selected from hydrogen, aromatic groups of C6-C 30 , heteroaryl groups of C3-C 30 , and at least one is not H;

[0011] The heteroatoms on the heteroaryl group are independently selected from O, S or N;

[0012] The hydrogen atoms on the aromatic group and heteroaryl group can be independently substituted by Ra, and Ra are independently selected from deuterium, halogen, nitro, cyano, C1-C4 alkyl groups, C5-C 20 cycloalkyl groups, phenyl groups, biphenyl groups, terphenyl groups or naphthyl groups.

[0013] Preferably, the R 1 -R 2 are independently selected from the following unsubstituted or Ra-substituted groups: phenyl group, biphenyl group, terphenyl group, naphthyl group, phenanthryl group, triphenylene group, fluorene group, benzofuran group, dibenzofuran group, benzothiophene group, dibenzothiophene group, 9,9-dimethylfluorene group, spirofluorene group, arylamine group, carbazolyl group.

[0014] Preferably, the R 3 -R 7 are independently selected from hydrogen, deuterium, C1-C4 alkanes, C5-C 10Cycloalkanes, the following groups which are unsubstituted or substituted by Ra: phenyl, biphenyl, terphenyl, naphthyl, phenanthryl, triphenylene, fluorenyl, benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, 9,9-dimethylfluorenyl, spirofluorene, arylamino, carbazolyl.

[0015] Preferably, the R 8 -R 9 are independently selected from each other from hydrogen, the following groups which are unsubstituted or substituted by Ra: phenyl, biphenyl, terphenyl, naphthyl, phenanthryl, triphenylene, fluorenyl, benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, 9,9-dimethylfluorenyl, spirofluorene, arylamino, carbazolyl.

[0016] More preferably, the compound is selected from the compounds shown as A1 - A20 below:

[0017]

[0018]

[0019] An object of the second aspect of the present invention is to provide a hole transporting material, which contains at least one of the compounds provided in the first aspect of the present invention.

[0020] An object of the third aspect of the present invention is to provide an organic electroluminescent device, which contains at least one of the hole transporting materials provided in the second aspect of the present invention.

[0021] An object of the fourth aspect of the present invention is to provide a display device, which contains the organic electroluminescent device provided in the third aspect of the present invention.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The compound disclosed in the present invention has a parent structure of substituted fluorenyl replacing arylamine, with high bond energy between atoms, good thermal stability, which is beneficial to the solid-state stacking between molecules, strong hole transition ability. When used as a hole transporting layer material, it can effectively reduce the device voltage and improve the material life. The fluorenyl structure substituted by a larger aromatic ring can enhance the charge transport ability of the molecule, improve the material stability, correspondingly improve the device luminescence efficiency and increase the life.

[0024] The compound of the present invention, when applied in the hole transporting layer, has a suitable energy level with the adjacent layer, which is beneficial to the injection and migration of holes, can effectively reduce the driving voltage. At the same time, with a high hole migration rate, it can achieve good luminescence efficiency in the device. The compound of the present invention has a large conjugated plane, which is beneficial to molecular stacking, shows good thermodynamic stability, and shows a long life in the device.

[0025] Meanwhile, the preparation process of the derivatives of the present invention is simple and easy to implement, and the raw materials are readily available, which is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only one embodiment of the present invention, and those of ordinary skill in the art can also obtain other embodiments according to these drawings.

[0027] Figure 1 It is a schematic structural diagram of a typical organic electroluminescent device. Each part is respectively:

[0028] 1. Substrate; 2. Reflective anode electrode; 3. Hole injection layer; 4. Hole transport layer; 5. Light-emitting layer; 6. Electron transport layer; 7. Electron injection layer; 8. Cathode electrode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following will clearly and completely describe the technical solutions in the present invention in conjunction with the drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0030] In the present invention, there is no particular limitation on the type and structure of the organic electroluminescent device, as long as the hole transport material provided by the present invention can be used.

[0031] The organic electroluminescent device of the present invention can be a light-emitting device with a top-emitting structure. For example, it sequentially includes an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a transparent or semi-transparent cathode on a substrate.

[0032] The organic electroluminescent device of the present invention can also be a light-emitting device with a bottom-emitting structure. For example, it sequentially includes a transparent or semi-transparent anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode structure on a substrate.

[0033] The organic electroluminescent device of the present invention can also be a light-emitting device with a double-sided emission structure. For example, it sequentially includes a transparent or semi-transparent anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a transparent or semi-transparent cathode structure on a substrate.

[0034] In the organic electroluminescent device of the present invention, except that the hole transport layer contains the hole transport material provided by the present invention, any material used for the layer in the prior art can be used for other layers.

[0035] Figure 1 FIG. shows a schematic diagram of a typical organic electroluminescent device, in which, from bottom to top, a substrate 1, a reflective anode electrode 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 electrode 8 are sequentially arranged.

[0036] It can be understood that Figure 1 Only the structure of a typical organic electroluminescent device is schematically shown, and the present invention is not limited to this structure. The hole transport material of the present invention can be used in any type of organic electroluminescent device. For example, the organic electroluminescent device may further include an electron blocking layer, a hole blocking layer, a light extraction layer, etc. In actual applications, these layers can be added or omitted according to specific circumstances.

[0037] For convenience, the organic electroluminescent device of the present invention will be described below with reference to Figure 1 However, this does not mean any limitation to the protection scope of the present invention. It can be understood that all organic electroluminescent devices capable of using the hole transport material of the present invention are within the protection scope of the present invention.

[0038] In the present invention, the substrate 1 is not particularly limited, and conventional substrates used in organic electroluminescent devices in the prior art can be used. For example, glass, polymer materials, and glass and polymer materials with TFT components, etc.

[0039] In the present invention, the material of the reflective anode electrode 2 is not particularly limited, and it can be selected from transparent conductive materials known in the prior art such as indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO), low-temperature polycrystalline silicon (LTPS), etc., or can be metal materials such as silver and its alloys, aluminum and its alloys, etc., or can be organic conductive materials such as PEDOT (poly-3,4-ethylenedioxythiophene), or a multilayer structure of the above materials, etc.

[0040] In the present invention, the material of the hole injection layer 3 is not particularly limited, and a hole injection material well-known in the art or the hole transport material provided by the present invention can be selected as the hole injection material.

[0041] For example, the material of the hole injection layer can be selected from at least one of the following compounds HT-1 to HT-31:

[0042]

[0043]

[0044]

[0045] In the present invention, the hole injection layer 3 may further include a p-type dopant. There is no particular limitation on the type of the p-type dopant, and various p-type dopants known in the art can be used. For example, the p-type dopant can be selected from at least one of the following compounds:

[0046]

[0047] In the present invention, there is no particular limitation on the amount of the p-type dopant used, and the amount can be known to those skilled in the art.

[0048] In the present invention, the hole transport layer 4 contains at least one of the hole transport materials of the present invention. The hole transport layer 4 may also contain any combination of at least one of the hole transport materials of the present invention and known hole transport materials. Currently known hole transport materials can be selected from at least one of the above-mentioned compounds HT-1 to HT-31, but are not limited to the compounds listed above.

[0049] In the present invention, there is no particular limitation on the luminescent material of the light-emitting layer 5, and any luminescent material known to those skilled in the art can be used. For example, the luminescent material may include a host material and a guest material. For example, it can be selected from at least one of the following compounds RH-1 to RH-13, but not limited thereto:

[0050]

[0051]

[0052] The host material of the light-emitting layer can also use at least one of the known host materials for green light-emitting layers in the art. For example, it can be selected from at least one of the following compounds GPH-1 to GPH-80, but not limited thereto:

[0053]

[0054]

[0055]

[0056] The host material of the light-emitting layer can also use at least one of the known host materials for blue light-emitting layers in the art. For example, it can be selected from at least one of the following compounds BH-1 to BH-10, but not limited thereto:

[0057] The host material of the light-emitting layer can be a host material for a red light-emitting layer. For example, it can be selected from at least one of the following compounds RPD-1 to RPD-28, but not limited thereto:

[0058]

[0059]

[0060] The host material of the light-emitting layer can be a host material for a green light-emitting layer. For example, it can be selected from at least one of the following compounds GD01 to GD04, but not limited thereto:

[0061]

[0062] The host material of the light-emitting layer can be a host material for a blue light-emitting layer. For example, it can be selected from at least one of the following compounds BD-1 to BD-9, but not limited thereto:

[0063]

[0064]

[0065] In the present invention, the material of the electron transport layer 6 is not particularly limited and can be made of electron transport materials well-known in the art. For example, the electron transport layer material can be selected from at least one of the following compounds ET-1 to ET-57:

[0066]

[0067]

[0068]

[0069] In the present invention, the electron transport layer 6 may further include an n-type dopant. The type of the n-type dopant is not particularly limited, and various n-type dopants known in the art can be used. For example, the n-type dopant can be a compound represented by the following formula:

[0070]

[0071] In the present invention, the amount of the n-type dopant is not particularly limited and can be an amount well-known to those skilled in the art.

[0072] In the present invention, the material of the electron injection layer 7 is not particularly limited, and electron injection materials well-known in the art can be used. For example, it can include at least one of the materials such as LiQ, LiF, NaCl, CsF, Li2O, Cs2CO3, BaO, Na, Li, Ca, etc. in the prior art.

[0073] In the present invention, the material of the cathode electrode 8 is not particularly limited. For example, it may be selected from, but not limited to, metals, metal mixtures, oxides such as magnesium-silver mixture, LiF / Al, ITO, Al, etc.

[0074] The display device provided by the present invention includes the organic electroluminescent device provided by the present invention. The display device includes, but is not limited to, a display, a television, a tablet computer, a mobile communication terminal, etc.

[0075] The method for preparing the organic electroluminescent device of the present invention is not particularly limited, and any method known in the art can be used. For example, the present invention can be prepared by the following preparation method:

[0076] (1) Clean the reflective anode electrode 2 on the substrate 1 of the top-emitting OLED device. In a cleaning machine, perform steps such as chemical cleaning, water washing, brushing, high-pressure water washing, air knife, etc., and then perform heat treatment;

[0077] (2) Vacuum deposit a hole injection material on the reflective anode electrode 2 as the hole injection layer 3;

[0078] (3) Vacuum deposit a hole transport material on the hole injection layer 3 as the hole transport layer 4;

[0079] (4) Vacuum deposit a light-emitting layer 5 on the hole transport layer 4. The light-emitting layer 5 contains a host material and a guest material;

[0080] (5) Vacuum deposit an electron transport material on the light-emitting layer 5 as the electron transport layer 6;

[0081] (6) Vacuum deposit an electron injection material on the electron transport layer 6 as the electron injection layer 7. The electron injection material is selected from one or a combination of several materials such as LiQ, LiF, NaCl, CsF, Li2O, Cs2CO3, BaO, Na, Li, Ca, etc.;

[0082] (7) Vacuum deposit a cathode material on the electron injection layer 7 as the cathode electrode 8.

[0083] The above only describes the structure and preparation method of a typical organic electroluminescent device. It should be understood that the present invention is not limited to this structure. The hole transport material of the present invention can be used in any structure of organic electroluminescent devices, and the organic electroluminescent devices can be prepared by any method known in the art.

[0084] The synthesis method of the compound of the present invention is not particularly limited, and any method known to those skilled in the art can be used for synthesis. The following is an example of the synthesis process of the compound of the present invention.

[0085] Synthesis Example 1: Synthesis of Compound A2

[0086]

[0087] Add 100 mmol of 2,6-dibromonaphthalene, 100 mmol of phenylboronic acid, 41.4 g of potassium carbonate (300 mmol), 800 ml of tetrahydrofuran (THF), and 200 ml of water to a reaction flask, and add 1 mol% of tetrakis(triphenylphosphine)palladium (Pd(PPh₃)₄). React at 60 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, concentrate the organic phase to obtain a white solid, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain a white powder M1. Among them, the addition amount of Pd(PPh₃)₄ is 1 mol% of 2,6-dibromonaphthalene.

[0088] Add 100 mmol of aniline, 100 mmol of M1, 28.83 g of sodium tert-butoxide (300 mmol), 800 ml of xylene to a reaction flask, and add 1 mol% of bis(dibenzylideneacetone)palladium (Pd(dba)). React at 120 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain a white powder M2. Among them, the addition amount of Pd(dba) is 1 mol% of aniline.

[0089] Add 100 mmol of 2-bromonaphthalene and 200 ml of THF to a reaction flask. At 0 °C, dropwise add 100 mmol of butyllithium. After the addition is completed, control the temperature and react for 1 h. Dissolve 100 mmol of 2-bromofluorene-9-one in 200 ml of THF, and drop the solution into the reaction flask. After the addition is completed, raise the temperature to room temperature and react for 12 h. After the reaction is completed, add water, separate the organic phase, concentrate, and obtain intermediate M3.

[0090] Add 100 mmol of M3, 100 mmol of biphenyl, and 10 ml of trifluoromethanesulfonic acid to a reaction flask, heat to reflux for water separation, and react for 12 h. After the reaction is completed, add water, a solid precipitates, filter, dry, and obtain intermediate M4.

[0091] Add 100 mmol of M2, 100 mmol of M4, 28.83 g of sodium tert-butoxide (300 mmol), 800 ml of xylene to a reaction flask, and add 1 mol% of bis(dibenzylideneacetone)palladium (Pd(dba)). React at 120 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain a white powder A2. Among them, the addition amount of Pd(dba) is 1 mol% of M2.

[0092] 11H NMR (400 MHz, Chloroform) δ 8.22 (s, 1H), 8.10 (d, J = 7.2 Hz, 1H), 7.92 (d, J = 6.8 Hz, 1H), 7.85 (d, J = 7.2 Hz, 1H), 7.80 (d, J = 8.0 Hz, 1H), 7.76 - 7.65 (m, 8H), 7.60 - 7.35 (m, 16H), 7.30 (d, J = 7.2 Hz, 2H), 7.21 (t, J = 7.2 Hz, 3H), 7.16 (s, 1H), 7.05 (t, J = 7.2 Hz, 3H), 6.94 (t, J = 7.2 Hz, 1H).

[0093] Synthesis Example 2: Synthesis of Compound A7

[0094]

[0095] Add 100 mmol of 2,6 - dibromonaphthalene, 100 mmol of 2 - naphthaleneboronic acid, 41.4 g of potassium carbonate (300 mmol), 800 ml of tetrahydrofuran (THF) and 200 ml of water into a reaction flask, and add 1 mol% of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4). React at 60 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, concentrate the organic phase to obtain a white solid, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain white powder M1. Among them, the addition amount of Pd(PPh3)4 is 1 mol% of 2,6 - dibromonaphthalene.

[0096] Add 100 mmol of M1, 100 mmol of aniline, 28.83 g of sodium tert - butoxide (300 mmol), 800 ml of xylene into a reaction flask, and add 1 mol% of bis(dibenzylideneacetone)palladium (Pd(dba)). React at 120 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain white powder M2. Among them, the addition amount of Pd(dba) is 1 mol% of M1.

[0097] Add 100 mmol of 2,2'-dibromospirobifluorene, 100 mmol of phenylboronic acid, 41.4 g of potassium carbonate (300 mmol), 800 ml of tetrahydrofuran (THF) and 200 ml of water into a reaction flask, and add 1 mol% of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4). React at 60 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, concentrate the organic phase to obtain a white solid, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain a white powder M3. Among them, the addition amount of Pd(PPh3)4 is 1 mol% of 2,2'-dibromospirobifluorene.

[0098] Add 100 mmol of M2, 100 mmol of M3, 28.83 g of sodium tert-butoxide (300 mmol), 800 ml of xylene into a reaction flask, and add 1 mol% of bis(dibenzylideneacetone)palladium (Pd(dba)). React at 120 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain a white powder A7. Among them, the addition amount of Pd(dba) is 1 mol% of M2.

[0099] 1 H NMR (400 MHz, Chloroform) δ 8.08 (t, J = 7.6 Hz, 3H), 8.01 (s, 1H), 7.97 (d, J = 7.2 Hz, 1H), 7.87 (d, J = 7.6 Hz, 2H), 7.82 (d, J = 7.6 Hz, 2H), 7.75 (d, J = 8.0 Hz, 2H), 7.70 - 7.55 (m, 8H), 7.50 (s, 1H), 7.43 - 7.24 (m, 7H), 7.22 - 7.10 (m, 6H), 7.06 (t, J = 7.2 Hz, 3H), 6.95 (s, 1H).

[0100] Synthesis Example 3: Synthesis of Compound A11

[0101]

[0102] Add 100 mmol of 2,6-dibromonaphthalene, 100 mmol of phenylboronic acid, 41.4 g of potassium carbonate (300 mmol), 800 ml of tetrahydrofuran (THF), and 200 ml of water into a reaction flask, and add 1 mol% of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4). React at 60 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, concentrate the organic phase to obtain a white solid, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain white powder M1. Among them, the addition amount of Pd(PPh3)4 is 1 mol% of 2,6-dibromonaphthalene.

[0103] Add 100 mmol of 5-chloro-1,2,3,4-tetrahydronaphthalene, 100 mmol of p-aminophenylboronic acid, 41.4 g of potassium carbonate (300 mmol), 800 ml of tetrahydrofuran (THF), and 200 ml of water into a reaction flask, and add 1 mol% of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4). React at 60 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, concentrate the organic phase to obtain a white solid, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain white powder M2. Among them, the addition amount of Pd(PPh3)4 is 1 mol% of 5-chloro-1,2,3,4-tetrahydronaphthalene.

[0104] Add 100 mmol of M1, 100 mmol of M2, 28.83 g of sodium tert-butoxide (300 mmol), 800 ml of xylene into a reaction flask, and add 1 mol% of bis(dibenzylideneacetone)palladium (Pd(dba)). React at 120 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain white powder M3. Among them, the addition amount of Pd(dba) is 1 mol% of M1.

[0105] Add 100 mmol of 4-bromo-terphenyl and 200 ml of THF into a reaction flask. At 0 °C, dropwise add 100 mmol of butyllithium. After the addition is completed, control the temperature and react for 1 h. Dissolve 100 mmol of 2-bromofluorene in 200 ml of THF, and drop the solution into the reaction flask. After the addition is completed, raise the temperature to room temperature and react for 12 h. After the reaction is completed, add water, separate the organic phase, concentrate, and obtain intermediate M4.

[0106] Add 100 mmol of M4, 200 ml of benzene, and 10 ml of trifluoromethanesulfonic acid into a reaction flask, heat to reflux for water separation, and react for 12 h. After the reaction is completed, add water, and a solid precipitates. Filter and dry to obtain intermediate M5.

[0107] Add 100 mmol of M3, 100 mmol of M5, 28.83 g of sodium tert-butoxide (300 mmol), 800 ml of xylene into a reaction flask, and add 1 mol% of bis(dibenzylideneacetone)palladium (Pd(dba)). React at 120 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain white powder A11. Among them, the addition amount of Pd(dba) is 1 mol% of M3.

[0108] 1 H NMR(400MHz,Chloroform)δ8.09(d,J=7.2Hz,1H),7.90(d,J=7.2Hz,2H),7.85(d,J=7.6Hz,2H),7.75(d,J=7.6Hz,4H),7.60-7.47(m,8H),7.45-7.30(m,12H),7.26-7.07(m,13H),7.02(d,J=8.0Hz,1H),2.75-2.67(m,4H),1.80-1.64(m,4H).

[0109] Synthesis Example 4: Synthesis of Compound A14

[0110]

[0111] Add 100 mmol of 2,6-dibromonaphthalene, 100 mmol of 9,9-dimethylfluorene-2-boronic acid, 41.4 g of potassium carbonate (300 mmol), 800 ml of tetrahydrofuran (THF) and 200 ml of water into a reaction flask, and add 1 mol% of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4). React at 60 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, concentrate the organic phase to obtain a white solid, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain white powder M1. Among them, the addition amount of Pd(PPh3)4 is 1 mol% of 2,6-dibromonaphthalene.

[0112] Add 100 mmol of aniline, 100 mmol of M1, 28.83 g of sodium tert-butoxide (300 mmol), 800 ml of xylene into a reaction flask, and add 1 mol% of bis(dibenzylideneacetone)palladium (Pd(dba)). React at 120 °C for 12 h. After the reaction is completed, stop the reaction, cool the reactant to room temperature, add water, filter, wash with water, and recrystallize and purify the obtained solid with toluene to obtain white powder M2. Among them, the addition amount of Pd(dba) is 1 mol% of aniline.

[0113] Add 200 mmol of 3-bromobiphenyl and 200 ml of THF to a reaction flask. At 0 °C, slowly add 220 mmol of butyllithium dropwise. After the addition is complete, maintain the temperature and react for 1 h. Dissolve 100 mmol of 2-bromofluorene-9-one in 200 ml of THF, and add this solution dropwise to the reaction flask. After the addition is complete, raise the temperature to room temperature and react for 12 h. After the reaction is complete, add water, separate the organic phase, and concentrate to obtain intermediate M3.

[0114] Add 100 mmol of M2, 100 mmol of M3, 28.83 g of sodium tert-butoxide (300 mmol), 800 ml of xylene to a reaction flask, and add 1 mol% of bis(dibenzylideneacetone)palladium (Pd(dba)). React at 120 °C for 12 h. After the reaction is complete, stop the reaction, cool the reactant to room temperature, add water, filter, wash with water, and recrystallize the obtained solid with toluene for purification to obtain white powder A14. Among them, the addition amount of Pd(dba) is 1 mol% of M2.

[0115] 1 H NMR (400 MHz, Chloroform) δ 8.26 (d, J = 7.2 Hz, 1H), 8.09 (d, J = 7.6 Hz, 1H), 8.04 (d, J = 7.2 Hz, 1H), 7.99 (s, 1H), 7.90 (d, J = 7.6 Hz, 2H), 7.84 (t, J = 7.6 Hz, 2H), 7.80 - 7.72 (m, 7H), 7.61 (d, J = 7.2 Hz, 1H), 7.55 - 7.31 (m, 16H), 7.28 - 7.15 (m, 7H), 7.10 (t, J = 6.8 Hz, 3H), 7.03 (t, J = 7.6 Hz, 1H), 1.69 (s, 6H).

[0116] Other compounds of the present invention can be synthesized by selecting appropriate raw materials according to the ideas of the above Synthesis Examples 1 - 4, or any other suitable methods and raw materials can also be selected for synthesis.

[0117] Example 1

[0118] Ultrasonically treat the glass plate coated with the ITO transparent conductive layer in a commercial cleaning agent, rinse it in deionized water, ultrasonically remove oil in an acetone-ethanol mixed solvent, bake it in a clean environment until all moisture is completely removed, clean it with ultraviolet light and ozone, and bombard the surface with a low-energy cation beam;

[0119] Place the above-mentioned glass substrate with the anode in a vacuum chamber, evacuate to less than 10 -5 Torr, and vacuum deposit HT-11 as the hole injection layer on the above-mentioned anode layer film at a deposition rate of 0.1 nm / s and a deposited film thickness of 10 nm;

[0120] Above the hole injection layer, A2 material is vacuum-evaporated as the hole transport layer at an evaporation rate of 0.1 nm / s, and the evaporated film thickness is 80 nm;

[0121] Above the hole transport layer, a light-emitting layer is vacuum-evaporated. The light-emitting layer includes a host material BH-4 and a dye material BD-1. The evaporation is carried out by the method of co-evaporation from multiple sources. The evaporation rate of the host material BH-4 is adjusted to 0.1 nm / s, and the evaporation rate of the dye BD-1 is 3% of the evaporation rate of the host material. The total evaporated film thickness is 20 nm;

[0122] Above the light-emitting layer, an electron transport layer is vacuum-evaporated. The material ET-42 is selected as the electron transport material, and its evaporation rate is 0.1 nm / s, and the evaporated film thickness is 30 nm;

[0123] On the electron transport layer (ETL), LiF with a thickness of 0.5 nm is vacuum-evaporated as the electron injection layer at an evaporation rate of 0.1 nm / s;

[0124] Finally, on the electron injection layer, an aluminum layer with a thickness of 150 nm is evaporated as the cathode of the organic electroluminescent device at an evaporation rate of 0.1 nm / s.

[0125] Example 2-4

[0126] Except that A7, A11, and A14 are used to replace A2 respectively, the rest is the same as in Example 1.

[0127] Comparative Example 1

[0128] Except that HT-27 is used to replace A2, the rest is the same as in Example 1.

[0129] Comparative Examples 2-4

[0130] For Comparative Examples 2-4, except that R-1, R-2, and R-3 are used to replace A2 respectively, the rest is the same as in Example 1.

[0131]

[0132] The following performance measurements are carried out on the organic electroluminescent devices prepared by the above process:

[0133] At the same brightness, a digital source meter and a luminance meter are used to measure the driving voltage, current efficiency, and device lifetime of the organic electroluminescent devices prepared in the examples and comparative examples. Specifically, the voltage is increased at a rate of 0.1 V per second, and the voltage when the brightness of the organic electroluminescent device reaches 1000 cd / m 2 is measured as the driving voltage, and the current density at this time is also measured; the ratio of brightness to current density is the current efficiency; the LT95 lifetime test is as follows: using a luminance meter at 1000 cd / m 2At a constant current under a certain brightness, measure the time when the brightness of the organic electroluminescent device drops to 950 cd / m 2 , in hours.

[0134] Table 1. Performance results of organic electroluminescent devices

[0135]

[0136]

[0137] From the data in Table 1, it can be seen that the compound prepared by the present invention used as a hole transport material for organic electroluminescent devices can effectively reduce the driving voltage, improve the current efficiency, and extend the device life, and it is a hole transport material with good performance.

[0138] The above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are all included in the protection scope of the present invention.

Claims

1. A compound, characterized in that, It has a structure represented by formula (I): Among them, R 1 -R 2 are each independently selected from an aryl group having 6 to 30 carbon atoms or a heteroaryl group having 3 to 30 carbon atoms, and at least one is selected from an aryl group or a heteroaryl group having 12 - 20 carbon atoms; R 1 , R 2 may be connected to form a ring; R 3 -R 7 Each independently selected from hydrogen, deuterium, C1-C4 alkanes, C5-C 10 cycloalkanes, C6-C 30 aryl groups of, C3-C 30 heteroaryl groups of, and adjacent substituents can be connected to form a ring; R 8 -R 9 Each independently selected from hydrogen, an aromatic group having 6 to 30 carbon atoms, a heteroaromatic group having 3 to 30 carbon atoms, and at least one is not H; The heteroatoms on the heteroaryl are each independently selected from O, S or N; The hydrogen atoms on the aryl group and heteroaryl group may each independently be replaced by Ra, and Ra are each independently selected from deuterium, halogen, nitro, cyano, C1-C4 alkyl, C5-C 20 cycloalkyl, phenyl, biphenyl, terphenyl or naphthyl.

2. The compound according to claim 1, characterized in that, Said R 1 -R 2 Each independently selected from the following groups which are unsubstituted or substituted by Ra: phenyl, biphenyl, terphenyl, naphthyl, phenanthryl, triphenylene, fluorene, benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, 9,9-dimethylfluorene, spirofluorene, arylamino, carbazolyl.

3. The compound according to claim 1, wherein Said R 3 -R 7 Each independently selected from hydrogen, deuterium, C1-C4 alkanes, C5-C 10 cycloalkanes, the following groups which are unsubstituted or substituted by Ra: phenyl, biphenyl, terphenyl, naphthyl, phenanthryl, triphenylene, fluorene, benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, 9,9-dimethylfluorene, spirofluorene, arylamine group, carbazolyl.

4. The compound according to claim 1, characterized in that, Said R 8 -R 9 Each independently selected from hydrogen and the following groups which are unsubstituted or substituted by Ra: phenyl, biphenyl, terphenyl, naphthyl, phenanthryl, triphenylene, fluorenyl, benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, 9,9-dimethylfluorenyl, spirofluorene, arylamino, carbazolyl.

5. The compound according to claim 1, wherein It is selected from the compounds shown in A1 - A20 below:

6. A hole transporting material, characterized in that, It contains at least one of the compounds described in any one of claims 1 - 5.

7. An organic electroluminescent device, characterized in that, It contains at least one of the hole - transporting materials of claim 6.

8. A display device, characterized in that, It contains the organic electroluminescent device of claim 7.

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