Carbazole compound and organic electroluminescent device

Abstract

The invention provides a carbazole compound and an organic electroluminescent device, and belongs to the technical field of organic electroluminescent materials. The carbazole compound has a structure as shown in a formula I. Through structural design of the carbazole compound, the carbazole compound with excellent performance is prepared, and the organic light-emitting device prepared by taking the carbazole compound as a material of a light-emitting layer has relatively high current efficiency, relatively long service life and relatively low driving voltage.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic electroluminescent materials, and particularly relates to a carbazole compound and an organic electroluminescent device. BACKGROUND

[0002] Compared with other flat panel displays (for example, liquid crystal display (LCD), plasma display panel (PDP), field emission display (FED), etc.), the organic electroluminescent device (OLED) has a simpler structure, various processing advantages, higher brightness, excellent viewing angle characteristics, faster response speed, and lower driving voltage, and therefore is fully developed to be used as a light source of a flat panel display (for example, a wall-mounted TV, etc.) or as a backlight unit of a display, an illuminator, an advertising board, etc.

[0003] The structure of the organic electroluminescent device is specifically an anode, a cathode, and an organic layer between the two. In order to improve the efficiency and stability of the organic electroluminescent element, the organic material layer includes multiple layers with different materials. In order to meet the higher requirements of OLED devices, more types of materials need to be developed in the field to improve the performance of OLED devices in terms of current efficiency, lifespan, etc. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application aims to provide a carbazole compound and an organic electroluminescent device. The present application designs the structure of the carbazole compound, and prepares a carbazole compound with excellent performance. The organic electroluminescent device prepared by using the carbazole compound as the material of the light-emitting layer has higher current efficiency, longer lifespan, and lower driving voltage.

[0005] To achieve this purpose, the present application adopts the following technical solutions:

[0006] In a first aspect, the present application provides a carbazole compound, which has the following structure shown in Formula I:

[0007]

[0008] wherein R1 and R2 are each independently selected from a phenyl group or a biphenyl group;

[0009] Ar1, Ar2, and Ar3 are each independently selected from any one of a C1-C12 alkyl group, a phenyl group, or a biphenyl group;

[0010] X is selected from C or Si;

[0011] The hydrogen atoms in the compound of Formula I can each independently be substituted with a deuterium atom (-D).

[0012] The application designs and prepares a carbazole compound with excellent performance, so that the carbazole compound as a material of a light-emitting layer, the prepared organic electroluminescent device has high current efficiency, long service life and low driving voltage.

[0013] In the application, C1-C12 can be C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11 or C12.

[0014] In the application, “-D” represents a deuterium atom, and in the application, H, hydrogen, which is not separately indicated, represents a mixture of protium, deuterium and tritium at natural abundance, and the same applies below.

[0015] The following is a preferred technical solution of the application, but is not a limitation on the technical solutions provided by the application. Through the following preferred technical solution, the purpose and beneficial effects of the application can be better achieved and realized.

[0016] As a preferred technical solution of the application, the C1-C12 alkyl is selected from any one of methyl, ethyl, propyl, butyl, pentyl, methylcyclopentyl, hexyl, methylcyclohexyl, heptyl, octyl, adamantyl, bicyclo[2.2.1]heptyl or bicyclo[2.2.2]octyl.

[0017] As a preferred technical solution of the application, Ar1, Ar2 and Ar3 are each independently selected from any one of methyl, ethyl, propyl, phenyl or biphenyl.

[0018] As a preferred technical solution of the application, at least one of R1 and R2 is selected from a phenyl group.

[0019] Preferably, R1 and R2 are both selected from a phenyl group.

[0020] As a preferred technical solution of the application, the carbazole compound is selected from any one of the following substituted or unsubstituted compounds:

[0021]

[0022]

[0023] The substitution means that the hydrogen atoms in the above-mentioned carbazole compound can each independently be replaced by a deuterium atom.

[0024] As a preferred technical solution of the application, the carbazole compound has any one of the structures shown in the following formula I-1 to formula I-4:

[0025]

[0026] In the compounds of formula I-1 to formula I-4, R1, R2, Ar1, Ar2, Ar3, and X each independently have the same meaning as defined above.

[0027] In the compounds of formula I-1 to formula I-4, each of the hydrogen atoms can be independently substituted with a deuterium atom.

[0028] Preferably, the carbazole compound is selected from any one of the following compounds:

[0029]

[0030] It should be noted that the preparation method of the carbazole compound is not particularly limited in the present application, and the preparation method commonly used in the art is applicable.

[0031] In a second aspect, the present application provides an organic electroluminescent device, which comprises an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode.

[0032] The material of the organic thin film layer comprises the carbazole compound as described in the first aspect.

[0033] Preferably, the organic thin film layer comprises a light-emitting layer, and the host material of the light-emitting layer comprises the carbazole compound as described in the first aspect.

[0034] Preferably, the light-emitting layer is a phosphorescent light-emitting layer.

[0035] As a preferred technical solution of the present application, the organic electroluminescent device is a blue organic electroluminescent device.

[0036] As a preferred technical solution of the present application, the organic electroluminescent device is a green organic electroluminescent device.

[0037] In the present application, the light-emitting layer comprises a light-emitting layer host material and a dopant material, wherein the dopant material is also called a dye or a phosphorescent light-emitting material. The light-emitting layer host material can be a single compound or a mixture formed by two or more compounds.

[0038] The light-emitting layer comprises a phosphorescent light-emitting layer, and the phosphorescent light-emitting layer comprises a green phosphorescent light-emitting layer, a red phosphorescent light-emitting layer, a yellow phosphorescent light-emitting layer, and a blue phosphorescent light-emitting layer.

[0039] The volume percentage of the host material in the phosphorescent light-emitting layer is 60% to 99.9% (for example, it can be 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99.9%, etc.), preferably 70% to 99.5%, and further preferably 85% to 95%.

[0040] In the present invention, the doping material for the light-emitting layer may be a phosphorescent material, which is also called a triplet light-emitting material and refers to a substance that emits light from a triplet excited state. The specific choice of phosphorescent material in the present invention is not particularly limited, and any doping material for the light-emitting layer commonly used in the art is applicable, including but not limited to compounds having a structure as shown in Formula PD:

[0041]

[0042] wherein M is selected from any one of Ir, Pt, Pd, Os, Ti, Zr, Hf, Eu, Tb, Tm, Cu, or Au;

[0043] Y1-Y4 are each independently selected from carbon or nitrogen;

[0044] Y1 and Y2 can be connected by a single bond or a double bond, and Y3 and Y4 can be connected by a single bond or a double bond;

[0045] Cy1 and Cy2 are each independently selected from any one of phenyl, naphthyl, fluorenyl, spirofluorenyl, indenyl, pyrrolyl, thienyl, furyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, quinolyl, isoquinolyl, benzoquinolyl, quinoxalinyl, quinazolinyl, carbazolyl, benzimidazolyl, benzofuranyl, benzothiophenyl, isobenzothiophenyl, benzimidazolyl, benzoxazolyl, triazolyl, tetrazolyl, oxadiazolyl, triazinyl, dibenzofuranyl, dibenzothiophenyl, N-heterocarbazolyl, N-heterodibenzofuranyl, wherein Cy1 and Cy2 may be optionally linked to each other via a single bond or an organic linking group;

[0046] Any two ligands of M, or more than two ligands, may be connected by a single bond or a double bond, or may be bridged by O or S, or may be connected by any chemical group or chemical structure to form a structural form that conforms to chemical principles;

[0047] R 91 and R 92Each is independently selected from -H, -D, -F, -Cl, -Br, -I, hydroxyl, cyano, nitro, amino, amidino, hydrazine, hydrazone, carboxylic acid, carboxylate, sulfonic acid, sulfonate, phosphoric acid, phosphate, -SF5, substituted or unsubstituted C1-C60 (for example, C1, C5, C10, C15, C20, C25, C30, C35, C40, C45, C50, C55 or C60, etc.) alkyl, substituted or unsubstituted C2-C6 C2, C5, C10, C15, C20, C25, C30, C35, C40, C45, C50, C55 or C60, etc.) alkenyl, substituted or unsubstituted C2-C60 (for example, C2, C5, C10, C15, C20, C25, C30, C35, C40, C45, C50, C55 or C60, etc.) alkynyl, substituted or unsubstituted C1-C60 (for example, C1, C5, C10, C15, C20, C25, C30, C35, C40, C45, C50, C55 or C60, etc.) C2-C10 (for example, C2, C3, C4, C5, C6, C7, C8, C9 or C10) heterocycloalkyl, substituted or unsubstituted C6-C60 (for example, C6, C12, C15, C18, C24, C30, C32, C36, C40, C42, C54 or C60) aryl, substituted or unsubstituted C6-C60 (for example, C6, C12, C15, C18, C24, C30, C32, C36, C40, C42, C54 or C60) aryl, substituted or unsubstituted C6-C60 ( For example, it can be any one of C6, C12, C15, C18, C24, C30, C32, C36, C40, C42, C54 or C60) aryloxy, substituted or unsubstituted C6-C60 (for example, it can be C6, C12, C15, C18, C24, C30, C32, C36, C40, C42, C54 or C60) arylthio, substituted or unsubstituted monovalent non-aromatic fused polycyclic group, and substituted or unsubstituted monovalent non-aromatic fused heteropolycyclic group.

[0048] a1 and a2 are each independently an integer selected from 1 to 5, for example, 1, 2, 3, 4 or 5;

[0049] b is an integer selected from 0-4, for example, 0, 1, 2, 3 or 4;

[0050] a is selected from 1, 2 or 3;

[0051] L1 is a monovalent organic ligand, a divalent organic ligand or a trivalent organic ligand.

[0052] Preferably, the compound of formula PD is selected from any one of the following compounds:

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059] In the present application, the organic thin film layer comprises a hole layer, and the hole layer comprises a hole injection layer, a hole transport layer and an electron blocking layer.

[0060] The hole injection layer material comprises a P-type dopant. The P-type dopant refers to coexisting with the hole injection layer material in the OLED device, which can oxidize the hole injection layer material, thereby serving as an electron acceptor, and can promote the movement of holes in the hole injection layer to the anode. In the present application, the absolute value of the LUMO of the P-type dopant and the absolute value of the HOMO of the hole layer material are greater than -0.2 V, preferably greater than -0.1 eV, further preferably greater than 0 eV, further preferably greater than 0.1 eV, further preferably greater than 0.2 eV.

[0061] The P-type dopant exists in the hole injection layer in a volume percentage of 1% to 10% (for example, it can be 1%, 2%, 4%, 6%, 8% or 10%, etc.). In the present application, the type of P-type dopant is not specially limited, and exemplary compounds can be selected from D-1 to D-13 disclosed in CN113728453A or the following HI-1 to HI-9 compounds:

[0062]

[0063]

[0064] In the present application, the hole layer material (including the hole injection layer, the hole transport layer and the electron blocking layer) has the structure shown in the following formula HT-GH4:

[0065]

[0066] L 41 is selected from a single bond, C6-C40 (for example, it can be C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36 or C40, etc.) aryl, C6-C20 (for example, it can be C6, C8, C10, C12, C16 or C20, etc.) heteroaryl;

[0067] Ar 41 , Ar42 Each is independently selected from C6-C40 (for example, C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36 or C40, etc.) aryl, C6-C20 (for example, C6, C8, C10, C12, C16 or C20, etc.) heteroaryl;

[0068] X is selected from CR 41 R 42 or NR 43 , where R 41 、R 42 、R 43 are each independently selected from any one of substituted or unsubstituted phenyl (the substituted substituent is selected from C1-C6 (for example, C1, C2, C3, C4, C5 or C6) alkyl, C1-C6 (for example, C1, C2, C3, C4, C5 or C6) alkoxy, dibenzofuranyl), naphthyl, triphenylene, fluoranthenyl, 9,9-dimethylfluorenyl, biphenyl, substituted or unsubstituted dibenzofuranyl (the substituted substituent is phenyl), substituted or unsubstituted dibenzothiophenyl (the substituted substituent is phenyl), dibenzofuran-substituted thienyl, C1-C6 (for example, C1, C2, C3, C4, C5 or C6) alkyl, R 41 、R 42 They can be linked to form rings via single bonds.

[0069] In the present invention, the hole layer material (including the hole injection layer, the hole transport layer and the electron blocking layer) also includes a compound having a structure shown in the following formula IA or a compound having a structure shown in the following formula IB:

[0070]

[0071] wherein L is selected from any one of a C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40) arylene group, a dibenzofuranyl group, or a dibenzothiophenyl group;

[0072] m is selected from an integer between 0 and 4 (for example, 0, 1, 2, 3 or 4), and n is selected from 0 or 1;

[0073] Ar is selected from any one of triphenylene, fluoranthenylene, dibenzofuranylene or dibenzothiophenylene;

[0074] Ar1and Ar2are each independently selected from any one of C6-C40 (e.g., can be C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aryl, dibenzofuranyl, or dibenzothiophenyl;

[0075] Ar1and Ar2, and Ar1, Ar2, are each independently connected or bridged by a single bond, O, S, CR1R2, NR.

[0076] R, R1, R2are each independently selected from any one of C1-C20 (e.g., can be C1, C2, C4, C6, C8, C10, C12, C14, C16, C18, or C20, etc.) alkyl, C6-C40 (e.g., can be C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aryl, dibenzofuranyl, or dibenzothiophenyl;

[0077] The hydrogen atoms in the compound of Formula IB and the compound of Formula IA can each independently be replaced by at least one of -F, -CN, -D (deuterium atom), C1-C6 alkyl, C1-C6 alkoxy, phenyl, biphenyl, naphthyl, phenanthryl, anthryl, fluorenyl, benzofluorenyl, dibenzofluorenyl, triphenylenyl, fluoranthenyl, pyrenyl, perylenyl, spirofluorenyl, indenofluorenyl, or hydrogenated benzanthracenyl.

[0078] Preferably, the Ar is a sub-fluoranthenyl group, and m+n > 1.

[0079] Preferably, the H in the compound of Formula IB and the compound of Formula IA can be replaced by at least one of -F, -CN, -D, C1-C3 alkyl (e.g., can be methyl, ethyl, or propyl), C1-C3 alkoxy (e.g., can be methoxy, ethoxy, or propoxy), phenyl, biphenyl, triphenylenyl, fluoranthenyl.

[0080] Preferably, the L, Ar1, Ar2are each independently selected from at least one of phenyl, biphenyl, naphthyl, phenanthryl, anthryl, fluorenyl, benzofluorenyl, dibenzofluorenyl, triphenylenyl, fluoranthenyl, pyrenyl, perylenyl, spirofluorenyl, indenofluorenyl, or hydrogenated benzanthracenyl.

[0081] Preferably, the compound of Formula IB is selected from any one of the following compounds:

[0082]

[0083]

[0084]

[0085] In the OLED device provided by the present invention, the hole layer material, in addition to the compound of formula HT-GH4, the compound of formula IB, and the compound of formula IA, may also include conventional hole materials in the art, without particular limitation. Exemplary examples include, but are not limited to, triarylamine compounds or carbazole compounds. Triarylamine compounds or carbazole compounds containing more than 3 N atoms are preferred, because the HOMO of triarylamine compounds or carbazole compounds containing more than 3 N atoms is higher (the absolute value is smaller), and they are more suitable for use as hole injection layer materials. Triarylamine compounds or carbazole compounds containing 2 or 1 N atoms can be used as hole transport layer materials. Some compounds or carbazole compounds containing 1 N atom, if they have a higher LUMO, can also be used as electron blocking layer materials.

[0086] The triarylamine compound or the carbazole compound is used as the hole layer material, and the hole layer material includes the following structure:

[0087]

[0088] Among them, Ar 601 ~Ar 609 Each independently selected from a substituted or unsubstituted C6-C40 (for example, C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36 or C40, etc.) aryl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted dibenzothiophenyl group, a substituted or unsubstituted naphthobenzofuranyl group, a substituted or unsubstituted naphthobenzothiophenyl group, a substituted or unsubstituted dinaphthofuranyl group, or a substituted or unsubstituted dinaphthothiophenyl group;

[0089] And Ar 601 ~Ar 609 Ar atoms adjacent to or connected to the same N atom 601 ~Ar 609 , can be connected by single key or through O, S, CR 701 R 702 NR 703 bridging;

[0090] R 701 、R 702 、R 703 is selected from C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aromatic groups, C6-C20 (e.g., C6, C8, C10, C12, C16, or C20, etc.) heteroaryl groups, C1-C6 (e.g., C1, C2, C3, C4, C5, or C6) alkyl groups, and R701 、R 702 Can connect via one-touch.

[0091] A hole-blocking layer (HBL) can confine holes and / or excitons within the emitting layer (EL) to improve device current efficiency and lifetime. Compared to the EL material closest to the HBL interface, the HBL material has a lower HOMO (larger absolute value) and / or higher triplet energy.

[0092] The electron transport layer (ETL) may include a material capable of transporting electrons. The electron transport layer may be intrinsic (undoped) or doped, and doping may be used to enhance conductivity. In the present invention, there is no particular restriction on the ETL material, and any metal complex or organic compound may be used as long as it can transport electrons. Generally, the electron transport layer material contains the following structural fragments: at least one of a pyridine structure, a pyrimidine structure, a triazine structure, a benzimidazole structure, a benzoxazole structure, a benzothiazole structure, an N-naphthalene structure, an N-heterophthalene structure, an N-heterocarbazole structure, an N-heterodibenzofuran structure, and an N-heterodibenzothiophene structure.

[0093] In the present invention, there is no particular limitation on the materials of the electron transport layer, and examples thereof include but are not limited to:

[0094]

[0095]

[0096]

[0097] In the present invention, the cathode material is a metal with a low work function (e.g., alkaline earth metals, alkali metals, main group metals, or lanthanides (e.g., Ca, Ba, Mg, Al, In, Mg, Yb, Sm, etc.)), a metal alloy composed of multiple metals (e.g., an alloy composed of an alkali metal or alkaline earth metal and silver, e.g., an alloy composed of magnesium and silver), or a multilayer structure. If the cathode material is a multilayer structure, in addition to the metals mentioned above, other metals with relatively high work functions, such as Ag or Al, may also be used. In this case, combinations of these metals are typically used, such as Ca / Ag, Mg / Ag, or Ba / Ag.

[0098] Alternatively, a thin intermediate layer of a material with a high dielectric constant may be introduced between the metal cathode and the organic semiconductor to form a multilayer structure. The material with a high dielectric constant may also be referred to as an electron injection material, and may be fluorides of alkali metals or alkaline earth metals, and corresponding oxides or carbonates (e.g., LiF, Li2O, BaF2, MgO, NaF, CsF, Cs2CO3, etc.) or lithium quinoline (LiQ).

[0099] Compared with the prior art, the present invention has the following beneficial effects:

[0100] The present invention designs the structure of carbazole compounds to prepare carbazole compounds with excellent performance. The organic electroluminescent device prepared by using the carbazole compounds as the material of the light-emitting layer has high current efficiency, long life and low driving voltage. DETAILED DESCRIPTION

[0101] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0102] Synthesis Example 1 Synthesis of Compound P1

[0103] This synthesis example provides compound P1 and its synthesis method, the synthesis method is as follows:

[0104]

[0105] Under a nitrogen atmosphere, dry toluene (80 mL), intermediate P1-1 (3.8 g), intermediate P1-2 (3.3 g), Pd(dba)2 (bis(dibenzylideneacetonepalladium, 0.1 g), 0.8 g of a 10% mass percentage tri-tert-butylphosphine toluene solution (the mass of tri-tert-butylphosphine is 0.08 g) and sodium tert-butoxide (1.2 g) were added to a three-necked flask, heated to reflux temperature, reacted for 8 h, cooled to room temperature, and separated by adding water. The organic layer was then washed with water until neutral, dried with magnesium sulfate, filtered to remove the magnesium sulfate, concentrated to dryness, and crystallized from a mixed solvent of toluene and ethanol to obtain compound P1 (4.9 g).

[0106] Compound P1 was subjected to mass spectrometry detection: its mass-to-charge ratio (m / z) was measured to be 616.29.

[0107] Synthesis Examples 2-7

[0108] Synthesis Examples 2-7 provide a compound and a synthesis method thereof, respectively. The synthesis method of the compound refers to the preparation method of compound P1, and the corresponding raw materials 1 and 2 are reacted to prepare the corresponding compounds. The mass spectra of the prepared compounds are measured and their mass-to-charge ratios m / z are recorded. Details are shown in Table 1 below:

[0109] Table 1

[0110]

[0111]

[0112]

[0113] The synthesis of other compounds not listed can be carried out according to the above examples, combined with common knowledge in the art. The specific structures of some compounds used in the following application examples and comparative application examples are as follows:

[0114]

[0115]

[0116] Application Example 1

[0117] This application example provides a blue light organic electroluminescent device, wherein the compound P1 provided by the present application is used as the host material of the light-emitting layer, and the structure of the blue light organic electroluminescent device is as follows:

[0118] ITO / HT-1:HI-2[5%](80nm) / HT-1(30nm) / EB-1(20nm) / Host material:PBD-1[5%](35nm) / ETL-1(25nm) / LiF(0.5nm) / Al(150nm).

[0119] The preparation method of the blue light organic electroluminescent device is as follows:

[0120] The materials are placed in a vacuum chamber, vacuumed to 1×10 -5 ~1×10 -6 Pa, and the above materials are vacuum evaporated on the cleaned ITO substrate in sequence to prepare an OLED device.

[0121] Among them, PBD-1[5%] refers to the doping ratio of the dye, that is, the volume ratio of the host material to the dye PBD-1 is 95:5; HT-1:HI-2[5%] refers to the ratio of the P-type dopant, that is, the volume ratio of the hole material HT-1 and the P-type dopant HI-2 is 95:5, and HT-1 is a hole transport material; HT-1:HI-2[5%] is used as a hole injection layer material, and EB-1 is an electron blocking layer material.

[0122] Application Example 2-4

[0123] Application Examples 2-4 respectively provide a blue light organic electroluminescent device, which is only different from the application example 1 in that the host material compound P1 of the light-emitting layer is replaced by other compounds (see Table 2 below for details), and the other preparation steps and conditions are the same as those of the application example 1.

[0124] Comparative Application Example 1

[0125] Comparative Application Example 1 provides an organic electroluminescent device, which is only different from the application example 1 in that the host material compound P1 of the light-emitting layer is replaced by other compounds (see Table 2 below for details), and the other preparation steps and conditions are the same as those of the application example 1.

[0126] Performance test

[0127] The luminance, driving voltage, current efficiency and LT95 of the organic electroluminescent device provided above were tested, wherein the current efficiency was 1000 cd / m 2 corresponding to the initial current density of 10 mA / cm 2 , the time required for the device efficiency to decrease to 95% of the efficiency corresponding to the initial current density, wherein the voltage, current efficiency and LT95 are relative values. The specific test results are shown in Table 2 below:

[0128] Table 2

[0129] Host material Dye <![CDATA[亮度 / (cd / m 2 )]]> Driving voltage Current efficiency LT95 Application Example 1 P1 PBD-1 1000 0.92 1.09 1.11 Application Example 2 P2 PBD-1 1000 0.96 1.13 1.14 Application Example 3 P3 PBD-1 1000 0.95 1.26 1.03 Application Example 4 P4 PBD-1 1000 0.78 1.02 1.03 Comparative Application Example 1 D2025-56-1 PBD-1 1000 1.00 1.00 1.00

[0130] From the above, it can be seen that in the present application, by designing the structure of the carbazole compound, an excellent carbazole compound is prepared, and thus the organic electroluminescent device prepared by using the carbazole compound as the material of the light-emitting layer has high current efficiency, long service life and low driving voltage.

[0131] After the specific position on the carbazole ring of the compound of the present application is substituted by a phenyl or biphenyl group, the degree of molecular twisting increases, the molecular film-forming property is better, and the charge mobility is improved, further improving the performance of the organic electroluminescent device prepared therefrom.

[0132] Application Examples 5-7, Comparative Application Examples 2-3

[0133] Application Examples 5-7, Comparative Application Examples 2-3 respectively provide a blue organic electroluminescent device, which is only different from Application Example 1 in that the host material compound P1 of the light-emitting layer is replaced by other compounds, and the dye PBD-1 is replaced by compound PBD-2 (see Table 3 below for details), and the other preparation steps and conditions are the same as those of Application Example 1.

[0134] Performance test

[0135] The luminance, driving voltage, current efficiency and LT95 of the organic electroluminescent device provided above were tested, wherein the current efficiency was 1000 cd / m 2 corresponding to the initial current density of 10 mA / cm 2 , the time required for the device efficiency to decrease to 95% of the efficiency corresponding to the initial current density, wherein the voltage, current efficiency and LT95 are relative values. The specific test results are shown in Table 3 below:

[0136] Table 3

[0137] Host material Dye Luminance / (cd / m 2 ) Driving voltage Current efficiency LT95 Application Example 5 P5 PBD-2 1000 1.05 1.06 1.03 Application Example 6 P6 PBD-2 1000 0.89 1.11 1.05 Application Example 7 P7 PBD-2 1000 1.04 1.09 0.96 Comparative Application Example 2 D2025-27-1 PBD-2 1000 1.00 1.00 1.00 Comparative Application Example 3 D2025-27-2 PBD-2 1000 1.04 0.92 0.88

[0138] As can be seen from the comparison between application example 6 and comparative application example 2, the positions of R1 and R2 in the carbazole compound shown in formula I are designed in the present application, so that after the specific position on the carbazole ring of the carbazole compound is substituted by phenyl or biphenyl, the degree of molecular distortion is increased, the film-forming property of the molecule is better, the charge mobility is improved, and the performance of the organic electroluminescent device is further improved.

[0139] In summary, the carbazole compound with excellent performance is prepared by designing the structure of the carbazole compound in the present application, and thus the organic electroluminescent device prepared by using the carbazole compound as the material of the light-emitting layer has high current efficiency, long service life and low driving voltage.

[0140] The applicant declares that the detailed process flow of the present application is illustrated by the above examples, but the present application is not limited to the above detailed process flow, that is, it does not mean that the present application must rely on the above detailed process flow to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A carbazole compound, characterized in that The carbazole compound has a structure shown in the following formula I: Wherein, R1 and R2 are each independently selected from phenyl or biphenyl; Ar1, Ar2, and Ar3 are each independently selected from any one of a C1-C12 alkyl group, a phenyl group, and a biphenyl group; X is selected from C or Si; The hydrogen atoms in the compounds of formula I may each independently be replaced by a deuterium atom.

2. The carbazole compound according to claim 1, wherein The C1-C12 alkyl group is selected from any one of methyl, ethyl, propyl, butyl, pentyl, methylcyclopentyl, hexyl, methylcyclohexyl, heptyl, octyl, adamantyl, bicyclo[2.2.1]heptyl or bicyclo[2.2.2]octyl.

3. The carbazole compound according to claim 1 or 2, characterized in that Ar1, Ar2, and Ar3 are independently selected from any one of methyl, ethyl, propyl, phenyl, and biphenyl.

4. The carbazole compound according to any one of claims 1 to 3, characterized in that At least one of R1 and R2 is selected from phenyl; Preferably, R1 and R2 are both selected from phenyl.

5. The carbazole compound according to any one of claims 1 to 4, characterized in that The carbazole compound is selected from any one of the following substituted or unsubstituted compounds: The substitution means that the hydrogen atoms in the carbazole compounds can be independently replaced by deuterium atoms.

6. The carbazole compound according to any one of claims 1 to 5, characterized in that The carbazole compound has any one of the structures shown in the following formulas I-1 to I-4: Wherein, R1, R2, Ar1, Ar2, Ar3, and X in the compounds of formula I-1 to formula I-4 have the same definitions as in claim 1; The hydrogen atoms in the compounds of formula I-1 to formula I-4 may each independently be substituted with a deuterium atom.

7. The carbazole compound according to any one of claims 1 to 6, characterized in that The carbazole compound is selected from any one of the following compounds:

8. An organic electroluminescent device, characterized in that: The organic electroluminescent device comprises an anode, a cathode and an organic thin film layer arranged between the anode and the cathode; The material of the organic thin film layer includes the carbazole compound according to any one of claims 1 to 7.

9. The organic electroluminescent device according to claim 8, characterized in that: The organic thin film layer includes a light-emitting layer, and the main material of the light-emitting layer includes the carbazole compound according to any one of claims 1 to 7; Preferably, the light-emitting layer is a phosphorescent light-emitting layer.

10. The organic electroluminescent device according to claim 8 or 9, characterized in that: The organic electroluminescent device is a blue organic electroluminescent device.

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