Carbazole compound, intermediate and organic electroluminescent device

Abstract

The invention provides a carbazole compound, an intermediate 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 invention belongs to the technical field of organic electroluminescent materials, and in particular relates to a carbazole compound, an intermediate and an organic electroluminescent device. Background Art

[0002] Compared with other flat panel displays (for example, liquid crystal displays (LCDs), plasma display panels (PDPs), field emission displays (FEDs), etc.), organic electroluminescent devices (OLEDs) have a simpler structure, various processing advantages, higher brightness, excellent viewing angle characteristics, faster response speeds, and lower driving voltages. Therefore, they have been fully developed to be used as light sources for flat panel displays (for example, wall-mounted TVs, etc.), or as backlight units for displays, illuminators, billboards, etc.

[0003] The structure of an organic electroluminescent device specifically consists of an anode, a cathode, and an organic layer between them. To improve the efficiency and stability of organic electroluminescent elements, the organic material layer can be composed of multiple layers of different materials. To meet the increasing demands for OLED devices, the field urgently needs to develop a wider variety of materials to improve OLED device performance in terms of current efficiency, lifespan, and other aspects. Summary of the Invention

[0004] To address the shortcomings of the prior art, the present invention provides a carbazole compound, an intermediate, and an organic electroluminescent device. By designing the structure of the carbazole compound, the present invention produces a carbazole compound with excellent performance. Organic electroluminescent devices prepared using the carbazole compound as the material for the light-emitting layer exhibit high current efficiency, a long lifespan, and a low driving voltage.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a carbazole compound having a structure shown in the following formula I:

[0007]

[0008] wherein R1 and R2 are each independently selected from a hydrogen atom or an N-carbazolyl group, and at least one of R1 and R2 is selected from an N-carbazolyl group;

[0009] X is selected from one of O and S;

[0010] The hydrogen atoms in the compound of formula I can be replaced independently by deuterium atoms (-D), -F, -CN, C1-C12 alkyl, C1-C12 alkoxy, triphenylsilyl ( The dotted line indicates the connection site, the same below), triphenylmethyl The compound is substituted with at least one of a C6-C20 aryl group or a C6-C20 heteroaryl group.

[0011] The N-carbazolyl group refers to a carbazolyl group whose connecting site is the N atom, that is,

[0012] The present invention designs carbazole compounds to prepare excellent performance carbazole compounds with relatively suitable HOMO and LUMO energy levels and good molecular film-forming properties. 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.

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

[0014] C6-C20 can be C6, C10, C12, C15, C18 or C20, etc.

[0015] In the present invention, "-D" represents a deuterium atom. Unless otherwise indicated, H and hydrogen therein represent "protium", and the same shall apply hereinafter.

[0016] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0017] As a preferred technical solution of the present invention, 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.

[0018] Preferably, the C1-C12 alkoxy group is selected from any one of methoxy, ethoxy, propoxy, butoxy, pentyloxy or hexyloxy.

[0019] Preferably, the C6-C20 aryl group is selected from any one of phenyl, naphthyl, biphenyl and 9,9-dimethylfluorenyl.

[0020] Preferably, the C6-C20 heteroaryl group is selected from any one of a carbazolyl group, a dibenzofuranyl group or a dibenzothiophenyl group.

[0021] As a preferred technical solution of the present invention, R1 is selected from N-carbazolyl, and R2 is selected from hydrogen atom.

[0022] As a preferred technical solution of the present invention, R1 is selected from a hydrogen atom, and R2 is selected from an N-carbazolyl group.

[0023] As a preferred technical solution of the present invention, R1 and R2 are both selected from N-carbazolyl.

[0024] As a preferred technical solution of the present invention, the hydrogen atoms in the compound of formula I can each independently be replaced by at least one of a deuterium atom (-D), -F, -CN, a methyl group, an ethyl group, a tert-butyl group, a phenyl group, a carbazolyl group, a triphenylsilyl group, and a triphenylmethyl group.

[0025] As a preferred technical solution of the present invention, the carbazole compound is selected from any one of the following substituted or unsubstituted compounds:

[0026]

[0027]

[0028] The substitution means that the hydrogen atoms in the above carbazole compound can be independently replaced by deuterium atoms. Preferably, the carbazole compound is selected from any one of the following compounds:

[0029]

[0030] It should be noted that, in the present invention, there is no special limitation on the preparation method of the carbazole compound, and any commonly used preparation method in the art is applicable.

[0031] In a second aspect, the present invention provides an intermediate comprising a compound having a structure shown in the following formula MA:

[0032]

[0033] Wherein, X1 is selected from any one of -F, -Cl, -Br, and -I;

[0034] R1 and R2 have the same meanings as above;

[0035] The hydrogen atoms in the compound of formula MA may each independently be substituted by at least one of a deuterium atom (-D), -F, -CN, a C1-C12 alkyl group, a C1-C12 alkoxy group, a triphenylsilyl group, a triphenylmethyl group, a C6-C20 aryl group, or a C6-C20 heteroaryl group;

[0036] The intermediates do not include the following compounds:

[0037]

[0038] The intermediate is used to prepare the carbazole compound as described in the first aspect.

[0039] As a preferred technical solution of the present invention, the intermediate includes the following compounds:

[0040]

[0041] Similarly, it should be noted that the present invention does not have any special limitations on the synthesis methods of intermediates, and all commonly used synthesis methods in the art are applicable.

[0042] The synthesis method of the intermediate compound MA of the present invention includes the following steps:

[0043]

[0044] Wherein, X1 and X2 are each independently selected from any one of -F, -Cl, -Br, and -I;

[0045] R1 and R2 have the same meanings as above;

[0046] The hydrogen atoms in the above raw materials and intermediate compound MA can each independently be replaced by at least one of a deuterium atom (-D), -F, -CN, a C1-C12 alkyl group, a C1-C12 alkoxy group, a triphenylsilyl group, a triphenylmethyl group, a C6-C20 aryl group or a C6-C20 heteroaryl group.

[0047] In a third aspect, the present invention provides an organic electroluminescent device, comprising an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode;

[0048] The material of the organic thin film layer includes the carbazole compound as described in the first aspect.

[0049] Preferably, the organic thin film layer includes a light-emitting layer, and the main material of the light-emitting layer includes the carbazole compound as described in the first aspect.

[0050] Preferably, the light-emitting layer is a phosphorescent light-emitting layer.

[0051] As a preferred technical solution of the present invention, the organic electroluminescent device is a blue organic electroluminescent device.

[0052] The luminescent layer of the present invention includes a luminescent layer host material and a dopant material, wherein the dopant material is also called a dye or a phosphorescent luminescent material. The luminescent layer host material can be a single compound or a mixture of two or more compounds.

[0053] The light-emitting layer includes a phosphorescent light-emitting layer, and the phosphorescent light-emitting layer includes 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.

[0054] The volume percentage of the main 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 more preferably 85% to 95%.

[0055] 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:

[0056]

[0057] wherein M is selected from any one of Ir, Pt, Pd, Os, Ti, Zr, Hf, Eu, Tb, Tm, Cu, or Au;

[0058] Y1-Y4 are each independently selected from carbon or nitrogen;

[0059] 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;

[0060] 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;

[0061] 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;

[0062] 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.

[0063] a1 and a2 are each independently an integer selected from 1 to 5, for example, 1, 2, 3, 4 or 5;

[0064] b is an integer selected from 0-4, for example, 0, 1, 2, 3 or 4;

[0065] a is selected from 1, 2 or 3;

[0066] L1 is a monovalent organic ligand, a divalent organic ligand or a trivalent organic ligand.

[0067] Preferably, the compound of formula PD is selected from any one of the following compounds:

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074] In the present invention, the organic thin film layer includes a hole layer, and the hole layer includes a hole injection layer, a hole transport layer and an electron blocking layer.

[0075] The hole injection layer material includes a P-type dopant. The P-type dopant coexists with the hole injection layer material in the OLED device and is capable of oxidizing the hole injection layer material, thereby acting as an electron acceptor and promoting the migration of holes from the hole injection layer toward the anode. In the present invention, the difference between the absolute value of the LUMO of the P-type dopant and the absolute value of the HOMO of the hole layer material is greater than -0.2V, preferably greater than -0.1eV, more preferably greater than 0eV, more preferably greater than 0.1eV, and even more preferably greater than 0.2eV.

[0076] The P-type dopant is present in the hole injection layer at a volume percentage of 1% to 10% (e.g., 1%, 2%, 4%, 6%, 8%, or 10%). In the present invention, there is no particular limitation on the type of the P-type dopant. For example, compounds D-1 to D-13 disclosed in CN113728453A or compounds HI-1 to HI-9 described below may be used:

[0077]

[0078]

[0079] In the present invention, the hole layer material (including the hole injection layer, the hole transport layer and the electron blocking layer) has a structure shown in the following formula HT-GH4:

[0080]

[0081] Among them, L 41 is selected from a single bond, a C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aryl, or a C6-C20 (e.g., C6, C8, C10, C12, C16, or C20, etc.) heteroaryl;

[0082] 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;

[0083] 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.

[0084] In the present invention, the hole layer material (including the hole injection layer, the hole transport layer and the electron blocking layer) further includes a compound having a structure as shown in the following formula IA or a compound having a structure as shown in the following formula IB:

[0085]

[0086] 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;

[0087] 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;

[0088] Ar is selected from any one of triphenylene, fluoranthenylene, dibenzofuranylene or dibenzothiophenylene;

[0089] Ar1 and Ar2 are each independently selected from any one of a C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aryl group, a dibenzofuranyl group, or a dibenzothiophenyl group;

[0090] Ar1 and Ar, Ar2 and Ar, and Ar1 and Ar2 can each independently be connected or bridged by a single bond, O, S, CR1R2, or NR.

[0091] R, R1, and R2 are each independently selected from any one of a C1-C20 (e.g., C1, C2, C4, C6, C8, C10, C12, C14, C16, C18, or C20) alkyl group, a C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40) aryl group, a dibenzofuranyl group, or a dibenzothiophenyl group;

[0092] The hydrogen atoms in the compound of formula IB and the compound of formula IA may each independently be replaced by at least one of -F, -CN, -D (deuterium atom), C1-C6 alkyl, C1-C6 alkoxy, phenyl, biphenyl, naphthyl, phenanthrenyl, anthracenyl, fluorenyl, benzofluorenyl, dibenzofluorenyl, triphenylene, fluoranthenyl, pyrenyl, perylenyl, spirofluorenyl, indenofluorenyl or hydrogenated benzanthryl.

[0093] Preferably, Ar is a fluoranthenyl group, and m+n>1.

[0094] Preferably, 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 (for example, methyl, ethyl or propyl), C1-C3 alkoxy (for example, methoxy, ethoxy or propoxy), phenyl, biphenyl, triphenylene, and fluoranthenyl.

[0095] Preferably, L, Ar1, and Ar2 are each independently selected from at least one of phenyl, biphenyl, naphthyl, phenanthryl, anthracenyl, fluorenyl, benzofluorenyl, dibenzofluorenyl, triphenylene, fluoranthenyl, pyrenyl, perylene, spirofluorenyl, indenofluorenyl, and hydrogenated benzanthryl.

[0096] Preferably, the compound of formula IB is selected from any one of the following compounds:

[0097]

[0098]

[0099] 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.

[0100] Preferably, the organic thin film layer includes an electron blocking layer, and the material of the electron blocking layer includes at least one of the following compounds:

[0101] Preferably, the material of the electron blocking layer comprises a compound

[0102] The triarylamine compound or the carbazole compound is used as the hole layer material, and the hole layer material includes the following structure:

[0103]

[0104] 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;

[0105] 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;

[0106] R 701 、R 702 、R 703is 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 R 701 、R 702 Can connect via one-touch.

[0107] 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.

[0108] 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.

[0109] In the present invention, there is no particular limitation on the electron transport layer materials, which exemplarily include but are not limited to:

[0110]

[0111]

[0112]

[0113] 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.

[0114] 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).

[0115] Compared with the prior art, the present invention has the following beneficial effects:

[0116] 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

[0117] 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.

[0118] Preparation Example 1

[0119] This preparation example provides intermediate P1-1 and its synthesis method, the synthesis method is as follows:

[0120]

[0121] Under a nitrogen atmosphere, 100 mL of dry toluene, 3.1 g of raw material M1, 3.3 g of raw material M2, 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 1.2 g of sodium tert-butoxide were added to a three-necked flask, heated to 60° C. for 4 hours, then heated to 70° C. for 4 hours, then refluxed for 1 hour, cooled to room temperature, and separated by water. The organic layer was then washed with water until neutral, dried over magnesium sulfate, filtered to remove the magnesium sulfate, concentrated to dryness, and separated by silica gel column chromatography and eluted with petroleum ether to obtain intermediate P1-1 (4.7 g).

[0122] The intermediate P1-1 was subjected to mass spectrometry detection: the mass-to-charge ratio (m / z) was measured to be 562.10.

[0123] Preparation Example 2

[0124] This preparation example provides the intermediate P4-1 and its synthesis method, the synthesis method is as follows:

[0125]

[0126] Referring to the preparation method of intermediate P1-1, intermediate P4-1 was prepared.

[0127] The intermediate P4-1 was subjected to mass spectrometry detection: the mass-to-charge ratio (m / z) was measured to be 562.10.

[0128] Synthesis Example 1 Synthesis of Compound P1

[0129] This synthesis example provides compound P1 and its synthesis method, the synthesis method is as follows:

[0130]

[0131] Under a nitrogen atmosphere, 50 mL of toluene, 20 mL of ethanol, and 15 mL of water were added to a three-necked flask, followed by 5.6 g of intermediate P1-1, 2.2 g of dibenzo[b,d]furan-2-boric acid, 2.12 g of sodium carbonate, and 0.23 g of tetrakistriphenylphosphine palladium. The temperature was slowly raised to reflux for 7 h, then cooled to room temperature, and water was added to separate the layers. The organic layer was washed with water, dried over magnesium sulfate, and after removing the desiccant, the mixture was concentrated to dryness and crystallized with ethanol to obtain compound P1 (3.6 g).

[0132] The obtained compound P1 was subjected to mass spectrometry detection, and the mass-to-charge ratio (m / z) was measured to be 650.24.

[0133] Synthesis Examples 2-5

[0134] Synthesis Examples 2-5 provide a compound and a synthesis method thereof, respectively. The synthesis method of the compound refers to the preparation method of compound P1 to prepare the corresponding compound, and the mass spectra of the prepared compound are measured and the m / z is recorded. Details are shown in Table 1 below:

[0135] Table 1

[0136]

[0137]

[0138] The synthesis of other compounds not listed here can be carried out by referring to the above examples in combination with common knowledge in the art. The specific structures of some of the compounds used in the following application examples and comparative application examples are as follows:

[0139]

[0140]

[0141] Among them, the synthesis method of compound D2:

[0142]

[0143] (1) Synthesis of intermediate D2-1

[0144] Intermediate D2-1 was prepared by referring to the preparation method of intermediate P1-1.

[0145] The mass spectrometry of intermediate D2-1 was performed: the mass-to-charge ratio (m / z) was 562.10

[0146] (2) Synthesis of Compound D2

[0147] Compound D2 was prepared by referring to the preparation method of compound P1.

[0148] The mass spectrometry of compound D2 was performed: the mass-to-charge ratio (m / z) was 650.24

[0149] Application Example 1

[0150] This application example provides a blue organic electroluminescent device, using the compound P4 provided by the present invention as the main material of the light-emitting layer. The structure of the blue organic electroluminescent device is:

[0151] ITO / HT-1: HI-2[5%](80nm) / HT-1(30nm) / EB-2(20nm) / host material: PBD-1[5%](35nm) / ETL-1(25nm) / LiF(0.5nm) / Al(150nm).

[0152] The preparation method of the blue organic electroluminescent device is as follows:

[0153] The material was placed in a vacuum chamber and evacuated to 1×10 -5 ~1×10 -6 Pa, vacuum evaporating the above materials onto the cleaned ITO substrate in sequence to prepare an OLED device.

[0154] Among them, PBD-1[5%] refers to the doping ratio of the dye, that is, the volume ratio of the main 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 the hole transport material; HT-1:HI-2[5%] is used as the hole injection layer material, and EB-2 is the electron blocking layer material.

[0155] Application Example 2-6

[0156] Application Examples 2-6 each provide a blue organic electroluminescent device, which differs from Application Example 1 only in that the main material compound P4 of the light-emitting layer is replaced with other compounds (see Table 2 below for details). Other preparation steps and conditions are the same as those of Application Example 1.

[0157] Comparative Application Examples 1-3

[0158] Comparative Application Examples 1-3 each provide an organic electroluminescent device. The only difference from Application Example 1 is that the host material compound P4 of the light-emitting layer is replaced with another compound (see Table 2 below for details), and the electron blocking layer material is replaced as needed. The remaining preparation steps and conditions are the same as those of Application Example 1.

[0159] Performance Testing

[0160] The brightness, driving voltage, current efficiency and LT95 of the organic electroluminescent device provided above were tested, wherein the current efficiency is the brightness of 1000cd / m 2 The corresponding value, LT95, refers to maintaining the initial current density of the device at 10mA / cm 2 The time required for the device efficiency to drop to 95% of the efficiency corresponding to the initial current density is constant, where the driving voltage, current efficiency and LT95 are relative values. The specific test results are shown in Table 2 below:

[0161] Table 2

[0162]

[0163] As can be seen from the above, the present invention has prepared carbazole compounds with excellent performance by designing the structure of the carbazole compounds. The organic electroluminescent devices prepared using the carbazole compounds as the material of the light-emitting layer have high current efficiency, long life and low driving voltage.

[0164] In compound P4, used in Application Example 1, two carbazoles are linked in a specific manner to form a dicarbazole group, with the meta position of the intermediate biphenyl group substituted by a dicarbazole group and a dibenzofuran group, respectively. Compared to compounds D1, D2, and D3 used in comparative examples 1-3, the organic electroluminescent device prepared using the carbazole compounds provided by the present invention exhibits superior overall performance.

[0165] From the comparison between Application Example 5 and Application Example 6, it can be seen that when the electron blocking layer material is EB-1, the performance of the organic electroluminescent device can be further improved.

[0166] Application Examples 7-9

[0167] Application Examples 7-9 each provide a blue organic electroluminescent device. The only difference from Application Example 1 is that the main material compound P4 of the light-emitting layer is replaced by other compounds, and EB-2 is replaced by compound EB-1 (see Table 3 below for details). The other preparation steps and conditions are the same as those in Application Example 1.

[0168] Performance Testing

[0169] The brightness, driving voltage, current efficiency and LT95 of the organic electroluminescent device provided above were tested, wherein the current efficiency is the brightness of 1000cd / m 2 The corresponding value, LT95, refers to maintaining the initial current density of the device at 10mA / cm 2 The time required for the device efficiency to drop to 95% of the efficiency corresponding to the initial current density is constant, where voltage, current efficiency and LT95 are relative values. The specific test results are shown in Table 3 below:

[0170] Table 3

[0171] Main material <![CDATA[Brightness / (cd / m 2 )]]> Driving voltage Current efficiency LT95 Application Example 7 Compound P2 1000 1 1 1 Application Example 8 Compound P3 1000 0.97 1.05 0.82 Application Example 9 Compound P8 1000 0.81 1.06 0.80

[0172] As can be seen from the above, the present invention has prepared carbazole compounds with excellent performance by designing the structure of the carbazole compounds. The organic electroluminescent devices prepared using the carbazole compounds as the material of the light-emitting layer have high current efficiency, long life and low driving voltage.

[0173] The applicant declares that the present invention uses the above-described embodiments to illustrate the detailed process flow of the present invention, but the present invention is not limited to the above-described detailed process flow, that is, it does not mean that the present invention must rely on the above-described detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for various raw materials in the products of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

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 a hydrogen atom or an N-carbazolyl group, and at least one of R1 and R2 is selected from an N-carbazolyl group; X is selected from one of O and S; The hydrogen atoms in the compound of formula I may each independently be substituted by at least one of a deuterium atom, -F, -CN, a C1-C12 alkyl group, a C1-C12 alkoxy group, a triphenylsilyl group, a triphenylmethyl group, a C6-C20 aryl group or a C6-C20 heteroaryl group.

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; Preferably, the C1-C12 alkoxy group is selected from any one of methoxy, ethoxy, propoxy, butoxy, pentyloxy or hexyloxy; Preferably, the C6-C20 aryl group is selected from any one of phenyl, naphthyl, biphenyl or 9,9-dimethylfluorenyl; Preferably, the C6-C20 heteroaryl group is selected from any one of a carbazolyl group, a dibenzofuranyl group or a dibenzothiophenyl group.

3. The carbazole compound according to claim 1 or 2, characterized in that R1 is selected from N-carbazolyl, and R2 is selected from hydrogen atom; Preferably, R1 is selected from a hydrogen atom, and R2 is selected from an N-carbazolyl group; Preferably, R1 and R2 are both selected from N-carbazolyl.

4. The carbazole compound according to any one of claims 1 to 3, characterized in that The hydrogen atoms in the compound of formula I can be independently replaced by at least one of a deuterium atom, -F, -CN, a methyl group, an ethyl group, a tert-butyl group, a phenyl group, a carbazolyl group, a triphenylsilyl group, and a triphenylmethyl group.

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 compound can be independently replaced by deuterium atoms.

6. An intermediate, characterized in that The intermediate includes a compound having a structure shown in the following formula MA: Wherein, X1 is selected from any one of -F, -Cl, -Br, and -I; R1 and R2 have the same meanings as in claim 1; The hydrogen atoms in the compound of formula MA may each independently be substituted by at least one of a deuterium atom, -F, -CN, a C1-C12 alkyl group, a C1-C12 alkoxy group, a triphenylsilyl group, a triphenylmethyl group, a C6-C20 aryl group, or a C6-C20 heteroaryl group; The intermediates do not include the following compounds: The intermediate is used to prepare the carbazole compound according to any one of claims 1 to 5.

7. The intermediate according to claim 6, characterized in that The intermediates include 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 5.

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 5; Preferably, the light-emitting layer is a phosphorescent light-emitting layer; Preferably, the organic thin film layer includes an electron blocking layer, and the material of the electron blocking layer includes at least one of the following compounds: Preferably, the material of the electron blocking layer comprises a compound 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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