Indolecarbazole compounds with symmetrical structures, their applications and organic electroluminescent devices

Abstract

The present invention relates to the field of organic electroluminescent devices, and discloses an indolecarbazole compound with a symmetrical structure, its application and an organic electroluminescent device, wherein the compound has a structure shown in formula (I). When the indolecarbazole compound with a symmetrical structure provided by the present invention is used in OLED, the OLED obtained thereby can have the advantages of high luminous efficiency, high color purity and long service life. #imgabs0#

Description

Technical Field

[0001] The invention relates to the field of organic electroluminescent devices, in particular to indolecarbazole compounds with symmetrical structures and applications thereof and organic electroluminescent devices. Background Art

[0002] Research on organic electroluminescence began as early as the 1960s. In 1963, Pope et al. at New York University in the United States observed blue electroluminescence of anthracene when they applied a 400V DC voltage to both sides of anthracene single crystals using electrolyte solutions as electrodes. However, due to the difficulty in growing single crystals and the high driving voltage, it had almost no practical use, but these early studies established an understanding of the entire process of organic electroluminescence.

[0003] The epoch-making development of organic electroluminescence was in the 1980s. In 1987, Tang et al. of Kodak Company prepared a double-layer organic electroluminescent diode by vacuum evaporation, using aromatic diamine as the hole transport layer and 8-hydroxyquinoline aluminum as the light-emitting layer. The driving voltage was less than 10V, the luminous efficiency was 1.5lm / W, and the luminous brightness was as high as 1000cd / m 2 This has made organic electroluminescent devices practical and has greatly promoted the research on organic electroluminescent devices and materials.

[0004] It is reported that the earliest OLED light-emitting layer was a layer of pure Alq3, and the device structure was simple, but due to the concentration quenching effect of the light-emitting material, the device efficiency was very low. In 1989, CW Tang et al. also proposed host-guest doping, where excitons recombine on the host material and then transfer energy to the guest for light emission, solving the guest concentration quenching problem, thereby improving the device's luminous efficiency and effectively solving the problem of short device life.

[0005] However, OLED devices or screens still have problems with high driving voltage and low luminous efficiency. Among them, blue light guest materials, especially deep blue light materials, are the shortcomings that affect the overall performance of OLED screens, including low exciton utilization, low luminous efficiency, low color purity, short service life, and concentration quenching, which is also a problem that needs to be solved urgently. In order to improve these defects, on the one hand, the device structure needs to be further optimized, and on the other hand, the performance of each functional layer and luminescent material needs to be improved. Among them, the guest material in the luminescent layer plays a vital role in luminous efficiency and color purity. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of low luminous efficiency, poor color purity and short service life of OLED provided by the prior art.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides an indolecarbazole compound having a symmetrical structure, wherein the compound has a structure shown in formula (I):

[0008]

[0009] Wherein, in formula (I),

[0010] Each R1 is the same and is H or D;

[0011] Each R2 is the same and is H or D;

[0012] Each R5 is the same and is H or D;

[0013] Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D;

[0014] R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl;

[0015] The combination A consists of C1-C6 alkyl, C1-C3 perdeuterated alkyl, cyano, halogen, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and C1-C3 alkyl substituted by at least one halogen.

[0016] The second aspect of the present invention provides use of the indolecarbazole compound with a symmetrical structure described in the first aspect in an organic electroluminescent device.

[0017] The third aspect of the present invention provides an organic electroluminescent device containing one or two or more of the aforementioned indolecarbazole compounds having a symmetrical structure.

[0018] When the indolecarbazole compound with a symmetrical structure provided by the present invention is used in OLED, the OLED obtained thereby can have the advantages of high luminous efficiency, high color purity and long service life. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] In the present invention, unless otherwise stated, the terms used are interpreted as follows:

[0021] D stands for deuterium.

[0022] Halogen includes fluorine, chlorine, bromine and iodine.

[0023] The C1-C6 alkyl group refers to a branched alkyl group having a total number of carbon atoms of 1 to 6 or a straight alkyl group having a total number of carbon atoms of 1 to 6, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, etc. The C1-C3 alkyl group has a similar explanation, except that the total number of carbon atoms is different.

[0024] The carbazole group is a structure shown in the following formula, wherein the wavy line indicates the connection position with the parent core structure:

[0025]

[0026] When the connection position of a substituent is not described in detail herein, it means that any position of the substituent that can be chemically bonded can be connected or substituted.

[0027] Likewise, the core described herein does not necessarily represent a general structure, but rather represents a structure to which the corresponding substituents are attached.

[0028] As mentioned above, the first aspect of the present invention provides an indolecarbazole compound having a symmetrical structure, wherein the compound has a structure shown in formula (I):

[0029]

[0030] Wherein, in formula (I),

[0031] Each R1 is the same and is H or D;

[0032] Each R2 is the same and is H or D;

[0033] Each R5 is the same and is H or D;

[0034] Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2The other is H or D;

[0035] R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl;

[0036] The combination A consists of C1-C6 alkyl, C1-C3 perdeuterated alkyl, cyano, halogen, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and C1-C3 alkyl substituted by at least one halogen.

[0037] According to a preferred embodiment, in formula (I),

[0038] Each R1 is the same and is H or D;

[0039] Each R2 is the same and is H or D;

[0040] Each R5 is the same and is H or D;

[0041] Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D;

[0042] R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl;

[0043] The combination A is composed of C1-C5 alkyl, perdeuterated methyl, perdeuterated ethyl, perdeuterated n-propyl, perdeuterated isopropyl, cyano, fluorine, chlorine, bromine, iodine, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and C1-C3 alkyl substituted by at least one halogen.

[0044] According to a first particularly preferred embodiment, in formula (I),

[0045] Each R1 is the same and is H;

[0046] Each R2 is the same and is H;

[0047] Each R5 is the same and is H;

[0048] Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D;

[0049] R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl;

[0050] The combination A is composed of C1-C5 alkyl, perdeuterated methyl, perdeuterated ethyl, perdeuterated n-propyl, perdeuterated isopropyl, cyano, fluorine, chlorine, bromine, iodine, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and C1-C3 alkyl substituted by at least one halogen.

[0051] In the aforementioned first preferred embodiment, preferably, the compound having the structure shown in formula (I) is selected from any one of the following:

[0052]

[0053]

[0054]

[0055]

[0056] According to a second particularly preferred embodiment, in formula (I),

[0057] Each R1 is the same and is D;

[0058] Each R2 is the same and is H;

[0059] Each R5 is the same and is H;

[0060] Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D;

[0061] R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl;

[0062] The combination A is composed of C1-C5 alkyl, perdeuterated methyl, perdeuterated ethyl, perdeuterated n-propyl, perdeuterated isopropyl, cyano, fluorine, chlorine, bromine, iodine, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and C1-C3 alkyl substituted by at least one halogen.

[0063] In the aforementioned second particularly preferred embodiment, preferably, the compound having the structure shown in formula (I) is selected from any one of the following:

[0064]

[0065]

[0066]

[0067] According to a third particularly preferred embodiment, in formula (I),

[0068] Each R1 is the same and is D;

[0069] Each R2 is the same and is D;

[0070] Each R5 is the same and is D;

[0071] Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D;

[0072] R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl;

[0073] The combination A is composed of C1-C5 alkyl, perdeuterated methyl, perdeuterated ethyl, perdeuterated n-propyl, perdeuterated isopropyl, cyano, fluorine, chlorine, bromine, iodine, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and C1-C3 alkyl substituted by at least one halogen.

[0074] In the aforementioned third particularly preferred embodiment, preferably, the compound having the structure shown in formula (I) is selected from any one of the following:

[0075]

[0076]

[0077]

[0078] According to the present invention, a fourth particularly preferred embodiment is provided, in formula (I),

[0079] Each R1 is the same and is H or D;

[0080] Each R2 is the same and is H or D;

[0081] Each R5 is the same and is H or D;

[0082] Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D;

[0083] R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl;

[0084] The combination A is composed of methyl, ethyl, n-propyl, isopropyl, tert-butyl, (CH3CH2)2CH-, perdeuterated methyl, perdeuterated ethyl, perdeuterated isopropyl, cyano, fluorine, chlorine, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and a C1-C3 alkyl group substituted by at least one halogen.

[0085] In the aforementioned fourth particularly preferred embodiment, preferably, the compound having the structure shown in formula (I) is selected from any one of the following:

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095] The present invention has no particular restrictions on the specific method for preparing the aforementioned compounds. Those skilled in the art can obtain the aforementioned compounds of the present invention according to the specific structural formula provided by the present invention in combination with the known process routes in the field of organic synthesis, and the present invention hereinafter exemplarily lists several examples to illustrate the preparation method of the compounds of the present invention. Those skilled in the art can also obtain the specific preparation method of all the remaining compounds by replacing the types of raw materials according to the preparation method of the compounds in the present invention hereinafter. The present invention no longer describes the preparation methods of all compounds in detail, and those skilled in the art should not be construed as limiting the present invention.

[0096] As mentioned above, the second aspect of the present invention provides the use of the indolecarbazole compound with a symmetrical structure described in the first aspect in an organic electroluminescent device.

[0097] As mentioned above, the third aspect of the present invention provides an organic electroluminescent device containing one or two or more of the indolecarbazole compounds with a symmetrical structure described in the first aspect.

[0098] Preferably, the indolecarbazole compound having a symmetrical structure is present in at least one of the hole transport layer, the electron blocking layer and the light-emitting layer of the organic electroluminescent device.

[0099] With particular preference, the compound is present in the light-emitting layer and / or the electron-blocking layer of the device.

[0100] Further preferably, the compound is a guest material in the light-emitting layer of the device.

[0101] Further preferably, the compound is a blue light guest material in the light-emitting layer of the device.

[0102] Preferably, the organic electroluminescent device of the present invention further comprises an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and a cathode.

[0103] According to some embodiments of the present invention, the anode material forming the anode is generally preferably a material with a large work function. For example, the anode material used in the present invention is selected from one or more of the following materials: metals, such as vanadium, chromium, copper and gold, or other alloys: metal oxides, such as zinc oxide, indium oxide, indium tin oxide, indium zinc oxide and tin dioxide, combinations of metals and oxides, such as zinc oxide: aluminum, but not limited thereto.

[0104] According to some embodiments of the present invention, the material forming the hole injection layer has the ability to transport holes, so the material of the hole injection layer has the effect of injecting holes into the anode, has an excellent hole injection effect on the light-emitting layer or the light-emitting material, prevents the excitons generated in the light-emitting layer from moving to the electron injection layer or the electron injection material, and has excellent thin film forming ability. The HOMO of the hole injection material is preferably between the work function of the anode material and the HOMO of the surrounding organic material layer.

[0105] According to some embodiments of the present invention, the material forming the hole transport layer is a material that can receive holes from the anode or the hole injection layer, move the holes to the light emitting layer, and has high mobility for holes.

[0106] According to some embodiments of the present invention, the hole injection material and the hole transport material include at least one of aromatic amine derivatives (such as NPB, SqMA1), hexaazatriphenylene derivatives (such as HACTN), indolecarbazole derivatives, conductive polymers (such as PEDOT / PSS), phthalocyanine or porphyrin derivatives, dibenzoindenofluorene amine, and spirobifluorene amine, but are not limited thereto.

[0107] According to some embodiments of the present invention, the hole injection layer and the hole transport layer may be formed by, for example, an aromatic amine derivative of the following general formula:

[0108]

[0109]

[0110] The groups R1 to R9 in the above general formula are each independently selected from a single bond, hydrogen, deuterium, alkyl, benzene, biphenyl, terphenyl, naphthalene, anthracene, phenanthrene, triphenylene, pyrene, fluorene, dimethylfluorene, spirobifluorene, carbazole, thiophene, benzothiophene, dibenzothiophene, furan, benzofuran, dibenzofuran, indole, indolecarbazole, indenocarbazole, pyridine, pyrimidine, imidazole, thiazole, quinoline, isoquinoline, quinoxaline, quinazoline, porphyrin, carboline, pyrazine, pyridazine or triazine.

[0111] According to some embodiments of the present invention, the material for forming the electron blocking layer is not particularly limited. Generally, compounds that meet the first and / or second conditions below can be considered for use:

[0112] First: It has a shallower LUMO energy level (smaller absolute value), the purpose of which is to reduce the number of electrons leaving the light-emitting layer, thereby increasing the probability of electrons and holes recombining in the light-emitting layer.

[0113] Second: It has a larger triplet energy, the purpose of which is to reduce the number of excitons leaving the light-emitting layer, thereby increasing the efficiency of exciton conversion to luminescence.

[0114] According to some embodiments of the present invention, the materials forming the electron blocking layer include but are not limited to aromatic amine derivatives (such as NPB) and spirobifluorenamine (such as SpMA2), wherein some electron blocking materials have structures similar to those of hole injection materials and hole transport materials.

[0115] According to some embodiments of the present invention, the light-emitting material of the light-emitting layer is a material that can emit light in the visible light region by receiving holes and electrons from the hole transport layer and the electron transport layer respectively and combining the holes and electrons, and is preferably a material with good quantum efficiency for fluorescence or phosphorescence.

[0116] According to some embodiments of the present invention, the light emitting layer may include a host material and a guest material.

[0117] According to some embodiments of the present invention, the host material may include anthracene derivatives, carbazole derivatives, fluorene derivatives, aromatic amine derivatives, silicone derivatives, carbazole-triazine derivatives, phosphorus-oxygen derivatives, and phenanthroline derivatives, but is not limited thereto.

[0118] In some preferred embodiments of the present invention, the anthracene derivative has the general formula shown below:

[0119]

[0120] The phosphorus-oxygen derivatives have the general formula shown below:

[0121]

[0122] In the general formula of the above-mentioned anthracene derivatives and phosphine-oxy derivatives, R11, R12, R13, R14, R15 and R16 are each independently selected from a single bond, hydrogen, deuterium, alkyl, benzene, diphenyl, terphenyl, quaterphenyl, naphthalene, phenylnaphthalene, anthracene, phenanthrene, triphenylene, pyrene, fluorene, carbazole, thiophene, benzothiophene, dibenzothiophene, furan, benzofuran, dibenzofuran, indole, indolecarbazole, indenocarbazole, pyridine, pyrimidine, imidazole, thiazole, quinoline, isoquinoline, quinoxaline, quinazoline, porphyrin, carboline, pyrazine, pyridazine or triazine, and groups represented by their substituents.

[0123] According to some embodiments of the present invention, when the guest material of the device contains the compound described in the first aspect of the present invention, the guest material is preferably a compound that produces emission via at least one of phosphorescence, fluorescence, TADF (thermally activated delayed fluorescence), MLCT (metal to ligand charge transfer), HLCT (with hybrid CT state) and triplet-triplet annihilation methods.

[0124] According to some embodiments of the present invention, the material of the hole blocking layer may also preferably be a compound having the following first and / or second conditions:

[0125] First: It has a deeper HOMO energy level (larger absolute value), the purpose of which is to reduce the number of holes leaving the light-emitting layer, thereby increasing the probability of electrons and holes recombining in the light-emitting layer.

[0126] Second: It has a larger triplet energy, the purpose of which is to reduce the number of excitons leaving the light-emitting layer, thereby increasing the efficiency of exciton conversion to luminescence.

[0127] According to some embodiments of the present invention, the material forming the hole blocking layer may include, for example, phenanthroline derivatives (eg, Bphen, BCP), triphenylene derivatives, benzimidazole derivatives, but is not limited thereto.

[0128] According to some embodiments of the present invention, the electron injection layer is a layer that injects electrons from the electrode, and the electron injection material is preferably a compound having the following properties: it has the ability to transport electrons, has the effect of injecting electrons from the cathode, has an excellent effect of injecting electrons into the light-emitting layer or the light-emitting material, prevents the excitons generated in the light-emitting layer from moving to the hole injection layer, and also has excellent film forming ability. The electron injection layer material includes, for example, LiF, CsF, Cs2CO3, LiQ, but is not limited thereto.

[0129] According to some embodiments of the present invention, the cathode material is preferably formed of a material with a small work function, which can smoothly inject electrons into the organic material layer. The cathode material that can be used in the present disclosure can be selected from one or more of the following materials, one or more of Al, Mg and Ag.

[0130] Through the above technical solution, the present invention has at least the following specific advantages:

[0131] 1. The organic compound provided by the present invention has a symmetrical structure, a uniform electron cloud distribution, and reduces non-radiative transition channels. When applied to organic electroluminescent devices, the luminous efficiency of the devices can be effectively improved.

[0132] 2. The organic compound provided by the present invention has the advantage of a narrow half-width. On the one hand, it can be applied to organic electroluminescent devices to improve the color purity of the device; on the other hand, it can improve the light extraction efficiency of the top-emitting device using the compound, thereby significantly improving the overall performance of the device without changing the electrical properties of the device.

[0133] 3. Furthermore, when the aforementioned organic compound of the present invention is applied to a device, the current density can be reduced and the life of the device can be increased while ensuring a certain brightness.

[0134] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, all the raw materials used are common commercial products.

[0135] Unless otherwise specified, the room temperature mentioned below means 25±1°C.

[0136] Preparation Example 1:

[0137]

[0138] Synthesis of intermediate M1-1: In a 1L three-necked flask, 3-bromophenylhydrazine hydrochloride (0.203 mol), 1,2-cyclohexanedione (0.102 mol), and ethanol (550 ml) were added in sequence, and concentrated sulfuric acid (0.98 g) was added dropwise within 3 minutes. Under nitrogen protection, the mixture was heated and stirred to 65°C. The reaction was completed after 4 hours. The mixture was cooled to room temperature, filtered, washed with ethanol and petroleum ether, and recrystallized to obtain a brown solid (yield: 73%).

[0139] Synthesis of intermediate M1-2: In a 500 ml three-necked flask, add intermediate M1-1 (0.07 mol), acetic acid (360 ml), and trifluoroacetic acid (0.45 mol). Under nitrogen protection, heat and stir, raise the temperature to reflux, and the reaction is completed after 10 hours. Cool to room temperature, filter, and recrystallize with acetic acid and petroleum ether to obtain a light yellow solid (yield: 70%).

[0140] Synthesis of intermediate M1: In a 500ml three-necked flask, add intermediate M1-2 (0.05mol), cesium carbonate (0.12mol), and DMF (200ml). Under nitrogen protection, heat with stirring and raise the temperature to reflux. The reaction is completed after 5h. Cool to room temperature, filter, and recrystallize with toluene and ethanol to obtain a light yellow solid (yield: 85%).

[0141] Mass spectrum: C24H12Br2N2, theoretical value: 485.94, measured value: 485.9. 1H-NMR (400 MHz, CDCl3) (ppm) δ = 7.04 ~ 7.09 (2H, m), 7.61 ~ 7.65 (2H, d), 7.66 ~ 7.68 (4H, s), 8.08 ~ 8.10 (2H, d), 8.23 ​​~ 8.25 (2H, s).

[0142] Preparation Example 2:

[0143]

[0144] Synthesis of intermediate M2: The synthesis method is the same as that of intermediate M1, and a light yellow solid is obtained (yield: 83%).

[0145] Mass spectrum: C24H8D4Br2N2, theoretical value: 489.96, measured value: 489.9. 1H-NMR (400 MHz, CDCl3) (ppm) δ = 7.05 ~ 7.10 (2H, m), 7.61 ~ 7.65 (2H, d), 8.08 ~ 8.10 (2H, d), 8.23 ​​~ 8.25 (2H, s).

[0146] Preparation Example 3:

[0147]

[0148] Synthesis of intermediate M3-1: The synthesis method is the same as that of intermediate M1-1, and a brown solid is obtained (yield: 75%).

[0149] Synthesis of intermediate M3-2: The synthesis method is the same as that of intermediate M1-2 to obtain a light yellow solid (yield: 70%).

[0150] Synthesis of intermediate M3: The synthesis method is the same as that of intermediate M1, and a light yellow solid is obtained (yield: 83%).

[0151] Mass spectrum: C24H12Br2N2, theoretical value: 485.94, measured value: 485.9. 1H-NMR (400 MHz, CDCl3) (ppm) δ = 7.13 ~ 7.17 (2H, m), 7.39 ~ 7.42 (2H, d), 7.66 ~ 7.68 (4H, s), 8.18 ~ 8.20 (2H, d), 8.25 ~ 8.28 (2H, s).

[0152] Preparation Example 4:

[0153]

[0154] Synthesis of intermediate M4: The synthesis method is the same as that of intermediate M1, and a white solid is obtained (yield: 80%).

[0155] Mass spectrum: C24H8D4Br2N2, theoretical value: 489.96, measured value: 489.9. 1H-NMR (400 MHz, CDCl3) (ppm) δ = 7.13 ~ 7.17 (2H, m), 7.39 ~ 7.41 (2H, d), 8.18 ~ 8.20 (2H, d), 8.25 ~ 8.28 (2H, s).

[0156] Preparation Example 5:

[0157]

[0158] Synthesis of intermediate M5-1: The synthesis method is the same as that of intermediate M1-1, and a brown solid is obtained (yield: 78%).

[0159] Synthesis of intermediate M5-2: The synthesis method is the same as that of intermediate M1-2 to obtain a light yellow solid (yield: 72%).

[0160] Synthesis of intermediate M5-3: The synthesis method is the same as that of intermediate M1, and a light yellow solid is obtained (yield: 81%).

[0161] Synthesis of intermediate M5-4: Under nitrogen protection, MoCl5 (1mmol) and C6D6 (103ml) (99% D) were stirred at room temperature, and then intermediate M5-3 (0.01mol) was added to the reaction mixture. After stirring for 1h, the reaction was quenched with 3mol / L hydrochloric acid solution, the organic phase was extracted with ether, the organic extract was washed with water and sodium bicarbonate in sequence, and then dried with anhydrous magnesium sulfate, and the crude product was obtained by rotary drying under reduced pressure, and purified by silica gel column chromatography using n-hexane as the eluent to obtain a white solid (yield: 90%, deuteration rate: 98%)

[0162] Synthesis of intermediate M5-5: In a 500ml three-necked flask, add intermediate M5-4 (0.05mol) and dichloromethane (190ml), add BBr3 (0.12mol) dropwise at 0°C, no obvious temperature rise during the dropwise addition, warm to room temperature after the addition is complete, react for 1h, and detect that the raw materials are basically reacted. Pour the reaction solution into ice water, add 2M sodium hydroxide aqueous solution to adjust to alkalinity (greater than 9), separate the organic phase, wash twice with water, separate the organic phase, and decompress and spin-dry to obtain a pink solid, heat with petroleum ether to pulp, cool and filter, and dry to obtain an off-white solid (yield: 45%).

[0163] Synthesis of intermediate M5: Add intermediate M5-5 (0.03 mol), pyridine (0.15 mol), and dichloromethane (120 ml) to a 2L three-necked flask and start stirring. Dissolve trifluoromethanesulfonic anhydride (0.09 mol) in 80 ml of dichloromethane and place in a 250 mL constant pressure dropping funnel. Cool to between 0 and 5°C, drop the above trifluoromethanesulfonic anhydride (nitrogen protection), and after the addition is complete, naturally raise the temperature to room temperature and react for 2 hours. Add 200 ml of water to the reaction system to obtain an organic phase, and concentrate the organic phase to obtain a light yellow solid (yield 90%).

[0164] Mass spectrum: C26D12F6N2O6S2, theoretical value: 638.08, measured value: 638.1.

[0165] Preparation Example 6:

[0166]

[0167] Synthesis of intermediate M6-1: The synthesis method is the same as that of intermediate M1-1, and a brown solid is obtained (yield: 75%).

[0168] Synthesis of intermediate M6-2: The synthesis method is the same as that of intermediate M1-2, and a light yellow solid is obtained (yield: 73%).

[0169] Synthesis of intermediate M6-3: The synthesis method is the same as that of intermediate M1, and a light yellow solid is obtained (yield: 83%).

[0170] Synthesis of intermediate M6-4: The synthesis method is the same as that of intermediate M5-4, and a light yellow solid is obtained (yield: 88%).

[0171] Synthesis of intermediate M6-5: The synthesis method is the same as that of intermediate M5-5 to obtain a light yellow solid (yield: 82%).

[0172] Synthesis of intermediate M6: The synthesis method is the same as that of intermediate M5 to obtain a light yellow solid (yield: 92%).

[0173] Mass spectrum: C26D12F6N2O6S2, theoretical value: 638.08, measured value: 638.1.

[0174] Compound Example 1:

[0175]

[0176] Synthesis of compound 7: In a 1L three-necked flask, the intermediate M1 (0.12mol), bis(4-isopropylphenyl)amine (0.25mol), sodium tert-butoxide (0.6mol), tri(dibenzylideneacetone)dipalladium (2.4mmol), tri-tert-butylphosphine (24ml) and toluene solvent (580ml) were sequentially added, stirred under nitrogen, and the temperature was raised to reflux for 8h. HPLC detected that the reaction of the raw materials was complete, and the reaction solution was cooled to room temperature. Dilute hydrochloric acid was added thereto to adjust the pH value to neutral, 300ml of deionized water was added, stirred, and separated. The organic phase was washed three times with toluene solvent and dried over anhydrous magnesium sulfate. The organic phase was removed by rotary evaporation to remove the solvent, and the residue was separated by silica gel column chromatography to obtain a yellow solid (yield: 78%).

[0177] Mass spectrum: C60H56N4, theoretical value: 832.45, measured value: 832.5. 1H-NMR (400 MHz, CDCl3) (ppm) δ = 1.18 ~ 1.19 (12H, s), 1.21 ~ 1.22 (12H, s), 2.83 ~ 2.93 (4H, m), 7.03 ~ 7.05 (3H, m), 7.06 ~ 7.08 (5H, m), 7.16 ~ 7.17 (5H, m), 7.19 ~ 7.21 (3H, m), 7.24 ~ 7.26 (3H, m), 7.28 ~ 7.29 (1H, m), 7.66 ~ 7.68 (4H, s), 8.22 ~ 8.28 (4H, m).

[0178] Compound Example 2:

[0179]

[0180] Synthesis of compound 6: The synthesis method is the same as that of compound 7 to obtain a light yellow solid (yield: 78%).

[0181] Mass spectrum: C52H28N8, theoretical value: 764.24, measured value: 764.3. 1H-NMR (400MHz, CDCl3) (ppm) δ = 7.24~7.26 (3H, m), 7.28~7.29 (1H, m), 7.34~7.38 (8H, m), 7.55~7.59 (8H, m), 7.66~7.68 (4H, s), 8.22~8.23 (1H, m), 8.25~8.26 (1H, m), 8.30~8.31 (2H, s).

[0182] Compound Example 3:

[0183]

[0184] Synthesis of compound 25: The synthesis method is the same as that of compound 7 to obtain a light yellow solid (yield: 81%).

[0185] Mass spectrum: C66H48N4O2, theoretical value: 928.38, found value: 928.4. 1H-NMR (400MHz, CDCl3) (ppm) δ = 1.18 ~ 1.19 (6H, s), 1.21 ~ 1.22 (6H, s), 2.81 ~ 2.93 (2H, m), 7.03 ~ 7.08 (4H, m), 7.15 ~ 7.21 (6H, m), 7 .24~7.26(3H,m), 7.27~7.31(2H,m), 7.33~7.43(3H,m), 7.47~7.56(4H,m), 7.62~7.6 4(1H,m), 7.65~7.68(5H,m), 7.96~8.00(4H,m), 8.22~8.23(1H,m), 8.25~8.26(1H,m).

[0186] Compound Example 4:

[0187]

[0188] Synthesis of compound 28: The synthesis method is the same as that of compound 7 to obtain a light yellow solid (yield: 79%).

[0189] Mass spectrum: C76H56N4, theoretical value: 1024.45, measured value: 1024.5. 1H-NMR (400MHz, CDCl3) (ppm) δ = 2.12 ~ 2.14 (12H, s), 6.19 ~ 6.20 (2H, s), 7.24 ~ 7.26 (3H, m), 7.28 ~ 7.29 (1H, m), 7.30 ~ 7.31 (1H, m), 7.33 ~ 7.3 4(2H,m), 7.37~7.41(2H,m), 7.41~7.44(5H,m), 7.45~7.47(4H,m), 7.48~7.53(6H,m), 7.66 ~7.68 (4H, s), 7.73 ~ 7.74 (8H, m), 7.75 ~ 7.78 (4H, m), 8.22 ~ 8.23 ​​(1H, m), 8.25 ~ 8.26 (1H, m).

[0190] Compound Example 5:

[0191]

[0192] Synthesis of compound 52: The synthesis method is the same as that of compound 7 to obtain a light yellow solid (yield: 80%).

[0193] Mass spectrum: C64H44D4N4, theoretical value: 876.41, measured value: 876.4. 1H-NMR (400MHz, CDCl3) (ppm) δ = 2.12~2.14 (12H, m), 6.88~6.93 (2H, m), 7.11~7.21 (6H, m), 7.24~7.28 (4H, m), 7.31~7.33 (2H, m), 7.39~7.51 (8H, m), 7.73~7.76 (6H, m), 7.84~7.85 (2H, s), 8.23~8.25 (2H, d).

[0194] Compound Example 6:

[0195]

[0196] Synthesis of compound 65: The synthesis method is the same as that of compound 7 to obtain a light yellow solid (yield: 77%).

[0197] Mass spectrum: C66H44D4N4O2, theoretical value: 932.40, measured value: 932.4. 1H-NMR (400MHz, CDCl3) (ppm) δ = 1.14~1.19 (6H, s), 1.21~1.24 (6H, s), 2.77~2.97 (2H, m), 7.03~7.09 (4H, m), 7.15~7.26 (6H, m), 7.24~7.43 (8H, m), 7.47~7.56 (4H, m), 7.62~7.66 (2H, m), 7.96~7.98 (3H, m), 7.99~8.00 (1H, m), 8.22~8.26 (2H, m).

[0198] Compound Example 7:

[0199]

[0200] Synthesis of compound 67: The synthesis method is the same as that of compound 7 to obtain a light yellow solid (yield: 84%).

[0201] Mass spectrum: C76H52D4N4, theoretical value: 1028.48, found value: 1028.5. 1H-NMR (400MHz, CDCl3) (ppm) δ = 2.12 ~ 2.14 (12H, s), 7.21 ~ 7.22 (2H, s), 7.24 ~ 7.26 (3H, m), 7.28 ~ 7.29 (1H, m), 7.30 ~ 7.3 1(1H, m), 7.33~7.34(2H, s), 7.37~7.42(2H, m), 7.43~7.44(4H, m), 7.45~7.47(4H , m), 7.48~7.53(6H,m), 7.73~7.77(13H,m), 8.22~8.23(1H,m), 8.25~8.26(1H,m).

[0202] Compound Example 8:

[0203]

[0204] Synthesis of Compound 78: The synthesis method is the same as that of Compound 7 to obtain a light yellow solid (yield: 80%).

[0205] Mass spectrum: C64H64N4, theoretical value: 888.51, measured value: 888.5. 1H-NMR (400MHz, CDCl3) (ppm) δ = 1.18~1.19 (12H, s), 1.21~1.22 (12H, s), 1.24~1.25 (12H, s), 7.04~7.08 (3H, m), 7.09~7.12 (5H, m), 7.15~7.18 (5H, m), 7.20~7.23 (3H, m), 7.24~7.26 (3H, m), 7.30~7.32 (1H, m), 7.68~7.69 (4H, s), 8.25~8.29 (4H, m).

[0206] Compound Example 9:

[0207]

[0208] Synthesis of Compound 81: The synthesis method is the same as that of Compound 7 to obtain a light yellow solid (yield: 84%).

[0209] Mass spectrum: C52H28D12N4, theoretical value: 732.40, measured value: 732.5. 1H-NMR (400MHz, CDCl3) (ppm) δ = 7.10~7.12 (2H, m), 7.13~7.15 (6H, m), 7.16~7.18 (6H, m), 7.19~7.21 (2H, m), 7.34~7.37 (4H, m), 7.66~7.68 (4H, m), 7.76~7.78 (2H, m), 8.21~8.23 (2H, s).

[0210] Compound Example 10:

[0211]

[0212] Synthesis of Compound 82: The synthesis method was the same as that of Compound 7 to obtain a light yellow solid (yield: 83%).

[0213] Mass spectrum: C48H12D20N4, theoretical value: 684.39, measured value: 684.4. 1H-NMR (400 MHz, CDCl3) (ppm) δ = 7.32 ~ 7.39 (4H, m), 7.66 ~ 7.69 (4H, m), 7.77 ~ 7.79 (2H, s), 8.21 ~ 8.23 ​​(2H, m).

[0214] Compound Example 11:

[0215]

[0216] Synthesis of compound 93: The synthesis method is the same as that of compound 7 to obtain a light yellow solid (yield: 76%).

[0217] Mass spectrum: C66H48N4O2, theoretical value: 928.38, measured value: 928.4. 1H-NMR (400MHz, CDCl3) (ppm) δ = 1.18~1.19 (6H, s), 1.20~1.22 (6H, s), 2.82~2.93 (2H, m), 7.03~7.08 (4H, m), 7.15~7.21 (6H, m), 7.24~7.43 (12H, m), 7.52~7.56 (2H, m), 7.62~7.68 (6H, m), 7.96~8.02 (4H, m).

[0218] Compound Example 12:

[0219]

[0220] Synthesis of compound 106: The synthesis method is the same as that of compound 7 to obtain a light yellow solid (yield: 75%).

[0221] Mass spectrum: C64H40N4, theoretical value: 864.33, found value: 864.3. 1H-NMR (400MHz, CDCl3) (ppm) δ = 6.42 ~ 6.43 (2H, s), 7.10 ~ 7.12 (4H, m), 7.32 ~ 7.34 (2H, m), 7.34 ~ 7.36 (5H, m), 7.37 ~ 7.38 (2H, m), 7.40 ~ 7.41 (3H, m), 7. 42~7.44(4H,m), 7.44~7.46(2H,m), 7.47~7.49(1H,m), 7.52~7.53(2H,m), 7.55~7.56(1H,m), 7 .60~7.62(2H,m), 7.63~7.65(2H,m), 7.67~7.67(4H,m), 7.69~7.70(2H,m), 7.72~7.73(2H,m).

[0222] Compound Example 13:

[0223]

[0224] Synthesis of compound 111: The synthesis method is the same as that of compound 7 to obtain a light yellow solid (yield: 80%).

[0225] Mass spectrum: C60H52D4N4, theoretical value: 836.48, measured value: 836.5. 1H-NMR (400MHz, CDCl3) (ppm) δ = 1.18~1.19 (12H, s), 1.21~1.22 (12H, s), 2.82~2.93 (4H, m), 7.04~7.08 (8H, m), 7.16~7.20 (8H, m), 7.35~7.36 (4H, m), 7.76~7.78 (2H, m), 8.22~8.22 (2H, s).

[0226] Compound Example 14:

[0227]

[0228] Synthesis of compound 116: The synthesis method is the same as that of compound 7 to obtain a light yellow solid (yield: 86%).

[0229] Mass spectrum: C48H24D4N4F4, theoretical value: 740.25, measured value: 740.3. 1H-NMR (400MHz, CDCl3) (ppm) δ = 7.09~7.10 (8H, m), 7.13~7.20 (8H, m), 7.32~7.39 (4H, m), 7.76~7.78 (2H, m), 8.21~8.24 (2H, m).

[0230] Compound Example 15:

[0231]

[0232] Synthesis of compound 141: The synthesis method is the same as that of compound 7 to obtain a light yellow solid (yield: 75%).

[0233] Mass spectrum: C60H52D12N4Si4, theoretical value: 964.50, measured value: 964.5. 1H-NMR (400 MHz, CDCl3) (ppm) δ = 1.06 ~ 1.08 (12H, s), 1.20 ~ 1.23 (12H, s), 1.25 ~ 1.26 (12H, s), 7.11 ~ 7.13 (2H, m), 7.14 ~ 7.16 (6H, m), 7.16 ~ 7.18 (6H, m), 7.19 ~ 7.21 (2H, m).

[0234] Compound Example 16:

[0235]

[0236] Synthesis of compound 150: The synthesis method was the same as that of compound 7 to obtain a light yellow solid (yield: 77%).

[0237] Mass spectrum: C66H36D12N4O2, theoretical value: 940.45, found value: 940.5. 1H-NMR (400MHz, CDCl3) (ppm) δ = 1.17-1.18 (6H, s), 1.22-1.23 (6H, s), 2.77-2.97 (2H, m), 7.03-7.08 (4H, m), 7.15-7.21 (6H, m) , 7.27~7.34(2H,m), 7.35~7.43(2H,m), 7.47~7.49(1H,m), 7.50~7.53(2H,m), 7.55~7. 56 (1H, m), 7.62~7.63 (1H, m), 7.65~7.66 (1H, m), 7.96~7.97 (1H, m), 7.99~8.01 (1H, m).

[0238] Compound Example 17:

[0239]

[0240] Synthesis of compound 181: The synthesis method was the same as that of compound 7 to obtain a light yellow solid (yield: 73%).

[0241] Mass spectrum: C66H36D12N4O2, theoretical value: 940.45, measured value: 940.5. 1H-NMR (400MHz, CDCl3) (ppm) δ = 1.17~1.19 (6H, s), 1.22~1.23 (6H, s), 2.73~3.02 (2H, m), 7.03~7.09 (4H, m), 7.15~7.21 (6H, m), 7.27~7.34 (2H, m), 7.36~7.43 (2H, m), 7.47~7.56 (4H, m), 7.62~7.67 (2H, m), 7.96~7.97 (1H, m), 7.99~8.01 (1H, m).

[0242] Compound Example 18:

[0243]

[0244] Synthesis of compound 187: The synthesis method was the same as that of compound 7 to obtain a light yellow solid (yield: 78%).

[0245] Mass spectrum: C76H44D12N4, theoretical value: 1036.53, measured value: 1036.5. 1H-NMR (400MHz, CDCl3) (ppm) δ = 2.13 ~ 2.13 (12H, s), 7.30 ~ 7.31 (2H, m), 7.33 ~ 7.34 (2H, m), 7.40 ~ 7.44 (6H, m), 7.46 ~ 7.47 (4H, m), 7.48 ~ 7.53 (6H, m), 7.73 ~ 7.74 (8H, m), 7.76 ~ 7.77 (4H, m).

[0246] Device Example 1

[0247] The glass plate coated with the ITO transparent conductive layer was ultrasonically treated in a commercial cleaning agent, rinsed in deionized water, ultrasonically degreased in a mixed solvent of acetone:ethanol (volume ratio 1:1), baked in a clean environment until the water was completely removed, cleaned with ultraviolet light and ozone, and bombarded with a low-energy cation beam;

[0248] Place the glass substrate with the anode in a vacuum chamber and evacuate to 1×10 -5Pa, vacuum evaporating HAT-CN as a hole injection layer on the above anode layer film, the evaporation rate is 0.1nm / s, and the total evaporation film thickness is 1nm; then evaporating the hole transport layer NPB, the evaporation rate is 0.1nm / s, and the thickness is 60nm;

[0249] The electron blocking layer TCTA of the device is vacuum evaporated on the hole transport layer, with an evaporation rate of 0.1nm / s and a total evaporation film thickness of 10nm;

[0250] The light-emitting layer of the device is vacuum-evaporated on the electron blocking layer. The light-emitting layer includes a main material and a guest material. The evaporation rate of the main material ADN is adjusted to 0.1nm / s, and the evaporation rate of the guest material compound 7 is set at 5% by using a multi-source co-evaporation method. The total evaporation film thickness is 30nm.

[0251] The hole blocking layer TPBi of the device was vacuum-deposited on the light-emitting layer at a rate of 0.1 nm / s and a thickness of 5 nm. Then, the electron transport layer was evaporated. The evaporation rates of ET-1 and ET-2 were adjusted to 0.1 nm / s by using a multi-source co-evaporation method, and the total evaporation film thickness was 30 nm.

[0252] LiF with a thickness of 0.5 nm was vacuum-evaporated on the electron transport layer (ETL) as an electron injection layer, and an Al layer with a thickness of 150 nm was used as the cathode of the device.

[0253] The molecular structures involved are as follows:

[0254]

[0255] Device Examples 2-18

[0256] Organic light-emitting devices of device examples 2 to 18 were prepared by a method similar to that of device example 1, except that compound 7 in device example 1 was replaced by a compound shown in Table 1.

[0257] Device Comparison Example 1-2

[0258] An organic electroluminescent device of Device Comparative Example 1 was prepared by a method similar to that of Device Example 1, except that Compound 7 in Device Example 1 was replaced by ref-1 and ref-2, respectively.

[0259]

[0260] Test Example 1

[0261] At brightness 1000cd / m 2 The driving voltage and current efficiency of the organic electroluminescent devices prepared in device examples 1 to 18 and device comparative examples 1 to 2 were measured. The results are shown in Table 1.

[0262] Table 1

[0263]

[0264]

[0265] The above results show that, compared with the comparative example, the organic compound of the present invention has a narrower half-peak width when applied to an organic electroluminescent device, so that the device has better color purity, higher device luminous efficiency and lower driving voltage.

[0266] Test Example 2

[0267] At brightness 1000cd / m 2 The lifespans of the organic electroluminescent devices prepared in device embodiments 3, 4, 6, 7, 11, 16, 17 and comparative examples 1 and 2 were measured. The results are shown in Table 2.

[0268] Table 2

[0269] Example No. Blue light guest material <![CDATA[Required luminance (cd / m 2 )]]> Lifespan (T90 / h) Example 3 Compound 25 1000 90 Example 4 Compound 28 1000 87 Example 6 Compound 65 1000 108 Example 7 Compound 67 1000 105 Embodiment 11 Compound 93 1000 89 Example 16 Compound 150 1000 133 Embodiment 17 Compound 181 1000 131

[0270] The above results show that the deuterated compound provided by the present invention has stronger stability and longer service life when applied to organic electroluminescent devices.

[0271] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. An indolecarbazole compound having a symmetrical structure, characterized in that: The compound has a structure shown in formula (I), Wherein, in formula (I), Each R1 is the same and is H or D; Each R2 is the same and is H or D; Each R5 is the same and is H or D; Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D; R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl; The combination A consists of C1-C6 alkyl, C1-C3 perdeuterated alkyl, cyano, halogen, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and C1-C3 alkyl substituted by at least one halogen.

2. The compound according to claim 1, wherein In formula (I), Each R1 is the same and is H or D; Each R2 is the same and is H or D; Each R5 is the same and is H or D; Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D; R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl; The combination A is composed of C1-C5 alkyl, perdeuterated methyl, perdeuterated ethyl, perdeuterated n-propyl, perdeuterated isopropyl, cyano, fluorine, chlorine, bromine, iodine, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and C1-C3 alkyl substituted by at least one halogen.

3. The compound according to claim 2, wherein In formula (I), Each R1 is the same and is H; Each R2 is the same and is H; Each R5 is the same and is H; Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D; R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl; The combination A is composed of C1-C5 alkyl, perdeuterated methyl, perdeuterated ethyl, perdeuterated n-propyl, perdeuterated isopropyl, cyano, fluorine, chlorine, bromine, iodine, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and C1-C3 alkyl substituted by at least one halogen.

4. The compound according to claim 3, wherein The compound of the structure shown in formula (I) is selected from any one of the following:

5. The compound according to claim 2, wherein In formula (I), Each R1 is the same and is D; Each R2 is the same and is H; Each R5 is the same and is H; Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D; R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl; The combination A is composed of C1-C5 alkyl, perdeuterated methyl, perdeuterated ethyl, perdeuterated n-propyl, perdeuterated isopropyl, cyano, fluorine, chlorine, bromine, iodine, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and C1-C3 alkyl substituted by at least one halogen.

6. The compound according to claim 5, wherein The compound of the structure shown in formula (I) is selected from any one of the following:

7. The compound according to claim 2, wherein In formula (I), Each R1 is the same and is D; Each R2 is the same and is D; Each R5 is the same and is D; Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D; R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl; The combination A is composed of C1-C5 alkyl, perdeuterated methyl, perdeuterated ethyl, perdeuterated n-propyl, perdeuterated isopropyl, cyano, fluorine, chlorine, bromine, iodine, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and C1-C3 alkyl substituted by at least one halogen.

8. The compound according to claim 7, wherein The compound of the structure shown in formula (I) is selected from any one of the following:

9. The compound according to claim 1 or 2, wherein In formula (I), Each R1 is the same and is H or D; Each R2 is the same and is H or D; Each R5 is the same and is H or D; Each R3 is the same, and each R4 is the same, and one of R3 and R4 is -NR 1 R 2 The other is H or D; R 1 and R 2 Each is independently selected from phenyl, biphenyl, phenyl substituted by at least one group in combination A, biphenyl substituted by at least one group in combination A, perdeuterated phenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, naphthyl, phenanthryl; The combination A is composed of methyl, ethyl, n-propyl, isopropyl, tert-butyl, (CH3CH2)2CH-, perdeuterated methyl, perdeuterated ethyl, perdeuterated isopropyl, cyano, fluorine, chlorine, trimethylsilyl, naphthyl, carbazolyl, naphthyl, and a C1-C3 alkyl group substituted by at least one halogen.

10. The compound according to claim 9, wherein The compound of the structure shown in formula (I) is selected from any one of the following:

11. Use of the indolecarbazole compound with a symmetrical structure according to any one of claims 1 to 10 in an organic electroluminescent device.

12. An organic electroluminescent device comprising one or more of the indolocarbazole compounds having a symmetrical structure as claimed in any one of claims 1 to 10.

13. The organic electroluminescent device according to claim 12, wherein: The indolecarbazole compound with a symmetrical structure exists in at least one of a hole transport layer, an electron blocking layer and a light-emitting layer of the organic electroluminescent device.

14. The organic electroluminescent device according to claim 13, wherein: The indolecarbazole compound with a symmetrical structure exists in the light-emitting layer and / or the electron blocking layer of the organic electroluminescent device.

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