A carbazole compound, an intermediate and an organic electroluminescent device

Abstract

The application provides a carbazole compound, an intermediate and an organic electroluminescent device. The application designs the structure of the carbazole compound, and an excellent carbazole compound is prepared, so that the carbazole compound is used as a light-emitting layer host material, and the prepared organic electroluminescent device has high current efficiency, long service life and low driving voltage.

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescent materials technology, specifically relating to a carbazole compound, an intermediate, and an organic electroluminescent device. Background Technology

[0002] Compared to other flat panel displays (e.g., liquid crystal displays (LCDs), plasma display panels (PDPs), field emission displays (FEDs), etc.), organic light-emitting devices (OLEDs) have a simpler structure, various processing advantages, higher brightness, excellent viewing angle characteristics, faster response speed, and lower driving voltage. Therefore, they have been fully developed for use as light sources for flat panel displays (e.g., wall-mounted TVs), or as backlight units for displays, lighting fixtures, advertising boards, etc.

[0003] The structure of an organic light-emitting diode (OLED) consists of an anode, a cathode, and an organic layer between them. To improve the efficiency and stability of OLEDs, the organic material layer comprises multiple layers of different materials. To meet the increasingly demanding requirements of OLED devices, there is an urgent need to develop a wider variety of materials to improve the performance of OLED devices in terms of current efficiency, lifetime, and other aspects. Summary of the Invention

[0004] This invention provides a carbazole compound, an intermediate, and an organic electroluminescent device. By designing the structure of the carbazole compound, this invention prepares a high-performance carbazole compound. Using this carbazole compound as the host material for the light-emitting layer, the resulting organic electroluminescent device exhibits high current efficiency, long lifetime, and low driving voltage.

[0005] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a carbazole compound having the structure shown in Formula I: Formula I; Among them, R1, R2, R3, and R4 are each independently selected from one of C6-C20 aryl and C3-C20 heteroaryl, and the linkage site of the C3-C20 heteroaryl is the carbon atom in the C3-C20 heteroaryl. In the compound of Formula I, each hydrogen atom can be independently replaced by a deuterium atom (-D), -F, -CN, a C1-C12 straight-chain or branched alkyl group, a C3-C12 cycloalkyl group, a C1-C12 alkoxy group, or a triphenylsilyl group. (The dashed line indicates the connection site, the same below), triphenylmethyl ( At least one of the following: ), C6-C20 aryl, C3-C20 heteroaryl.

[0006] This invention designs the structure of carbazole compounds to prepare high-performance carbazole compounds. Using carbazole compounds as the main material of the light-emitting layer, the resulting organic electroluminescent devices have high current efficiency, long lifespan, and low driving voltage.

[0007] In this invention, C1-C12 can be C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11 or C12.

[0008] C3-C12 can be C3, C4, C5, C6, C7, C8, C9, C10, C11 or C12.

[0009] C6-C20 can be C6, C8, C10, C12, C18, or C20, etc.

[0010] C3-C20 can be C3, C4, C5, C7, C8, C9, C12, C18, or C20, etc.

[0011] In this invention, "-D" represents a deuterium atom. Unless otherwise specified, "-H" and "hydrogen" both represent "protium".

[0012] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0013] Preferably, the straight-chain or branched alkyl group of C1-C12 is selected from any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, and n-undecyl.

[0014] Preferably, the C3-C12 cycloalkyl group is selected from any one of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or adamantyl.

[0015] Preferably, the alkoxy group of C1-C12 is selected from any one of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, cyclopentoxy, n-hexyloxy, or cyclohexyloxy.

[0016] Preferably, the aryl group of C6-C20 is selected from any one of phenyl, naphthyl, biphenyl, terphenyl, 9,9-dimethylfluorenyl, triphenylene, anthracene, phenanthrene, or fluoranthyl.

[0017] Preferably, the heteroaryl group of C3-C20 is selected from any one of triazinyl, carbazoleyl, dibenzofuranyl, dibenzothiophenyl, naphthobenzofuranyl or naphthobenzothiophenyl.

[0018] Preferably, R1 and R2 are each independently selected from aryl groups of C6-C20; Preferably, R1 and R2 are each independently selected from any one of phenyl, naphthyl, biphenyl, terphenyl, and 9,9-dimethylfluorenyl, and more preferably any one of phenyl, biphenyl, and naphthyl.

[0019] Preferably, R3 and R4 are each independently selected from any one of phenyl, naphthyl, biphenyl, terphenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, and carbazoleyl.

[0020] Preferably, the hydrogen atoms in the compound of Formula I can each be independently selected from any one of deuterium (-D), -F, -CN, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclopentyl, cyclohexyl, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, n-hexoxy, phenyl, naphthyl, and biphenyl.

[0021] Preferably, the carbazole compound is selected from the following substituted or unsubstituted compounds: ; The substitution refers to the independent replacement of each hydrogen atom in the carbazole compound by a deuterium atom.

[0022] Preferably, the carbazole compound is selected from any one of the following compounds: , , , , , , , , , , , .

[0023] In this invention, there are no special limitations on the preparation method of the above-mentioned carbazole compounds, and commonly used preparation methods in the art are applicable.

[0024] Secondly, the present invention provides an intermediate having the structures shown in formulas MA and MB: , ; Among them, X1 and X2 are each independently selected from any one of -F, -Cl, -Br or -I; R1, R2, R3, and R4 have the same definitions as above; In the compounds of formula MA and formula MB, the hydrogen atoms can be independently substituted by at least one of the following: a deuterium atom, -F, -CN, C1-C12 alkyl, C1-C12 alkoxy, triphenylsilyl, triphenylmethyl, C6-C20 aryl, or C3-C20 heteroaryl.

[0025] Preferably, the intermediate comprises the following compounds: , , , , .

[0026] The preparation of compounds represented by formulas MA and MB, and their application in the preparation of compounds of formula I, are illustrated below with examples: ; Among them, X1, X2, and X3 are each independently selected from any one of -F, -Cl, -Br, or -I; R1, R2, R3, and R4 have the same definitions as above; The hydrogen atoms in each of the above-mentioned raw materials and intermediate compounds can be independently substituted by at least one of deuterium, -F, -CN, C1-C12 alkyl, C1-C12 alkoxy, triphenylsilyltriphenylmethyl, C6-C20 aryl, or C3-C20 heteroaryl.

[0027] In a second aspect, the present invention provides an organic electroluminescent device, the organic electroluminescent device comprising an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode; The material of the organic thin film layer includes carbazole compounds as described in the first aspect.

[0028] Preferably, the organic thin film layer includes a light-emitting layer, and the main material of the light-emitting layer includes carbazole compounds as described in the first aspect.

[0029] Preferably, the light-emitting layer is a phosphorescent light-emitting layer.

[0030] Preferably, the organic electroluminescent device is a blue organic electroluminescent device.

[0031] In this invention, the light-emitting layer comprises a host material and a dopant material, wherein the dopant material is also called a dye or a phosphorescent material. The host material of the light-emitting layer can be a single compound or a mixture of two or more compounds.

[0032] The light-emitting layer includes a phosphorescent light-emitting layer, which 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.

[0033] The volume percentage of the main material in the phosphorescent luminescent layer is 60% to 99.9% (e.g., it can be 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or 99.9%), preferably 70% to 99.5%, and more preferably 85% to 95%.

[0034] In this invention, the doping material of the light-emitting layer can be a phosphorescent material, also known as a triplet luminescent material, which refers to the light emitted by a substance from a triplet excited state. The specific selection of phosphorescent materials in this invention is not particularly limited; commonly used doping materials for the light-emitting layer in this field are applicable, including but not limited to: compounds having a structure as shown in formula PD. PD; Wherein, M is selected from any one of Ir, Pt, Pd, Os, Ti, Zr, Hf, Eu, Tb, Tm, Cu or Au; Y1-Y4 are each independently selected from carbon or nitrogen; Y1 and Y2 can be connected by a single key or a double key, and Y3 and Y4 can be connected by a single key or a double key. Cy1 and Cy2 are each independently selected from any one of phenyl, naphthyl, fluorenyl, spirofluorenyl, indyl, pyrroleyl, thiopheneyl, furanyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, quinolinyl, isoquinolinyl, benzoquinolinyl, quinoxalinyl, quinazolinyl, carbazoleyl, benzimidazolyl, benzofuranyl, benzothiopheneyl, isobenzothiopheneyl, benzimidazolyl, benzozolyl, triazolyl, tetrazolyl, diazolyl, triazinyl, dibenzofuranyl, dibenzothiopheneyl, N-hexacarbazolyl, N-hexadibenzofuranyl, wherein Cy1 and Cy2 may optionally be linked to each other via a single bond or an organic linking group; Any two or more ligands of M can be connected by single or double bonds, or by O or S bridging, or by any chemical group or chemical structure to form a structure that conforms to chemical principles. R 91 and R 92Each group is independently selected from -H, -D, -F, -Cl, -Br, -I, hydroxyl, cyano, nitro, amino, amidine, hydrazine, hydrazone, carboxylic acid group, carboxylate group, sulfonic acid group, sulfonate group, phosphate group, phosphate group, -SF5, substituted or unsubstituted C1-C60 (e.g., can be C1, C5, C10, C15, C20, C25, C30, C35, C40, C45, C50, C55, or C60, etc.) alkyl, substituted or unsubstituted C2-C6. 0 (e.g., can be C2, C5, C10, C15, C20, C25, C30, C35, C40, C45, C50, C55, or C60, etc.) alkenyl, substituted or unsubstituted C2-C60 (e.g., can be C2, C5, C10, C15, C20, C25, C30, C35, C40, C45, C50, C55, or C60, etc.) alkynyl, substituted or unsubstituted C1-C60 (e.g., can be C1, C5, C10, C15, C20, C40, C50, C55, C60, etc.) alkyne, substituted or unsubstituted C1-C60 (e.g., can be C1, C5, C10, C15, C20, C50, C10, C15, C20, C1 ... 25. alkoxy, substituted or unsubstituted C2-C10 (e.g., can be C2, C3, C4, C5, C6, C7, C8, C9, or C10), heterocyclic alkyl, substituted or unsubstituted C6-C60 (e.g., can be 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 the following: aryloxy group (C6, C12, C15, C18, C24, C30, C32, C36, C40, C42, C54 or C60, etc.), substituted or unsubstituted C6-C60 (e.g., it can be C6, C12, C15, C18, C24, C30, C32, C36, C40, C42, C54 or C60, etc.), substituted or unsubstituted monovalent non-aromatic fused polycyclic group, or substituted or unsubstituted monovalent non-aromatic fused heterocyclic group.

[0035] a1 and a2 are each independent integers selected from 1 to 5, for example, they can be 1, 2, 3, 4 or 5; b is an integer selected from 0 to 4, for example, it can be 0, 1, 2, 3 or 4; a is selected from 1, 2, or 3; L1 can be a monovalent organic ligand, a divalent organic ligand, or a trivalent organic ligand.

[0036] Preferably, the PD compound is selected from any one of the following compounds: .

[0037] In this invention, the organic thin film layer includes a hole layer, which comprises a hole injection layer, a hole transport layer, and an electron blocking layer.

[0038] The hole injection layer material includes a P-type dopant. A P-type dopant is a material that coexists with the hole injection layer material in the OLED device, oxidizing the hole injection layer material and thus acting as an electron acceptor to promote the movement of holes from the hole injection layer to the anode. In this 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 more preferably greater than 0.2eV.

[0039] The P-type dopant exists in the hole injection layer at a volume percentage of 1% to 10% (e.g., 1%, 2%, 4%, 6%, 8%, or 10%, etc.). In this invention, no special limitation is made on the type of P-type dopant; for example, compounds D-1 to D-13 disclosed in CN113728453A or compounds HI-1 to HI-9 as described below can be used. .

[0040] In this invention, the hole layer material (including a hole injection layer, a hole transport layer, and an electron blocking layer) has the structure shown in the following formula HT-GH4: ; Among them, L 41 Selected from single-bonded, C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aryl, and C6-C20 (e.g., C6, C8, C10, C12, C16, or C20, etc.) heteroaryl; Ar 41 Ar 42Each is independently selected from C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aryl and C6-C20 (e.g., C6, C8, C10, C12, C16, or C20, etc.) heteroaryl; X is selected from CR 41 R 42 Or NR 43 , where R 41 R 42 R 43 Each is independently selected from substituted or unsubstituted phenyl groups (the substituents are selected from C1-C6 (e.g., C1, C2, C3, C4, C5, or C6) alkyl, C1-C6 (e.g., C1, C2, C3, C4, C5, or C6) alkoxy, dibenzofuranyl, naphthyl, triphenylene, fluoranyl, 9,9-dimethylfluorenyl, biphenyl, substituted or unsubstituted dibenzofuranyl (the substituent is phenyl), substituted or unsubstituted dibenzothiophenyl (the substituent is phenyl), dibenzofuran-substituted thiophenyl, C1-C6 (e.g., C1, C2, C3, C4, C5, or C6) alkyl, R 41 R 42 A ring can be formed by connecting the links with a single key.

[0041] In this invention, the hole layer material (including a hole injection layer, a hole transport layer, and an electron blocking layer) further includes a compound having a structure as shown in Formula IA or a compound having a structure as shown in Formula IB: Formula ⅠA; Formula IB; Wherein, L is selected from any one of C6-C40 (e.g., it can be C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36 or C40, etc.) arylene, dibenzofuranyl or dibenzothiophene group; m is selected from an integer between 0 and 4 (for example, it can be 0, 1, 2, 3 or 4), and n is selected from 0 or 1; Ar is selected from any one of triphenylene, fluorene anthracene, dibenzofuranyl or dibenzothiophene; Ar1 and Ar2 are each independently selected from any one of aryl, dibenzofuranyl, or dibenzothiophene groups containing C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.); Ar1 and Ar, Ar2 and Ar, and Ar1 and Ar2 can be independently connected or bridged by single bonds, O, S, CR1R2, NR.

[0042] R, R1, and R2 are each independently selected from any one of the following: C1-C20 (e.g., C1, C2, C4, C6, C8, C10, C12, C14, C16, C18, or C20), alkyl, C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40), aryl, dibenzofuranyl, or dibenzothiopheneyl. In compounds of formula IB and formula IA, the hydrogen atoms can be independently replaced by at least one of -F, -CN, -D (deuterium atom), C1-C6 alkyl, C1-C6 alkoxy, phenyl, biphenyl, naphthyl, phenanthryl, anthracene, fluorenyl, benzo[a]fluorenyl, dibenzo[a]fluorenyl, triphenylene, fluoranyl, pyrene, peryl, spirofluorenyl, indo[a]fluorenyl, or hydrogenated benzo[a]anthryl.

[0043] Preferably, the Ar is fluoreneanthracene, where m+n>1.

[0044] Preferably, the H in the compounds of formula IB and formula IA can be replaced by at least one of -F, -CN, -D, C1-C3 alkyl (e.g., methyl, ethyl, or propyl), C1-C3 alkoxy (e.g., methoxy, ethoxy, or propoxy), phenyl, biphenyl, triphenylene, or fluoranthyl.

[0045] Preferably, L, Ar1, and Ar2 are each independently selected from at least one of phenyl, biphenyl, naphthyl, phenanthryl, anthracene, fluorenyl, benzo[a]fluorenyl, dibenzo[a]fluorenyl, triphenylene, fluoranyl, pyrene, perylene, spirofluorenyl, indo[a]fluorenyl, or hydrogenated benzo[a]anthryl.

[0046] Preferably, the compound of formula IB is selected from any one of the following compounds: .

[0047] In the OLED device provided by this invention, the hole layer material, in addition to the compounds described in formula HT-GH4, formula IB, and formula IA, may also include conventional hole materials in the art, without particular limitation. Exemplarily, it includes, but is not limited to, triarylamine compounds or carbazole compounds. Triarylamine compounds or carbazole compounds containing three or more nitrogen atoms are preferred because they have a higher HOMO (lower absolute value) and are more suitable as hole injection layer materials. Triarylamine compounds or carbazole compounds containing two or one nitrogen atom can be used as hole transport layer materials. Some compounds or carbazole compounds containing one nitrogen atom, if they have a high LUMO, can also be used as electron blocking layer materials.

[0048] The triaryl amine compound or carbazole compound is used as the hole layer material, and the hole layer material includes the following structure: ; Among them, Ar 601 ~Ar 609 Each is independently selected from any one of the following: substituted or unsubstituted C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aryl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiophene, substituted or unsubstituted naphthobenzofuranyl, substituted or unsubstituted naphthobenzothiophene, substituted or unsubstituted dinaphthofuranyl, substituted or unsubstituted dinaphthothiophene. And Ar 601 ~Ar 609 Ar atoms that are adjacent to or connected to the same N atom 601 ~Ar 609 It can be connected via a single key or via O, S, CR 701 R 702 NR 703 bridging; R 701 R 702 R 703 Selected from C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aryl, C6-C20 (e.g., C6, C8, C10, C12, C16, or C20, etc.) heteroaryl, C1-C6 (e.g., C1, C2, C3, C4, C5, or C6) alkyl, and R 701 R 702 It can be connected with a single button.

[0049] Hole blocking layers (HBLs) can confine holes and / or excitons within the emissive layer to improve device current efficiency and lifetime. Compared to emissive layer materials closest to the HBL interface, HBL materials exhibit lower HOMO (larger absolute values) and / or higher triplet energies.

[0050] An electron transport layer (ETL) may comprise a material capable of transporting electrons. The ETL may be intrinsic (undoped) or doped, and doping can be used to enhance conductivity. In this invention, there are no particular limitations on the ETL material; any metal complex or organic compound can be used, as long as it can transport electrons. Generally, electron transport layer materials contain at least one of the following structural segments: pyridine, pyrimidine, triazine, benzimidazole, benzoxazole, benzothiazole, N-naphthalene, N-phenanthion, N-carbazole, N-dibenzofuran, and N-dibenzothiophene.

[0051] In this invention, no special restrictions are placed on the electron transport layer material, which includes, but is not limited to, the following: .

[0052] In this invention, the cathode material is a metal with 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 (an alloy composed of alkali metals or alkaline earth metals and silver, such as 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 function can also be used, such as Ag or Al. In this case, combinations of the metals are typically used, such as Ca / Ag, Mg / Ag, or Ba / Ag.

[0053] Alternatively, a thin interlayer of material with a high dielectric constant can be introduced between the metal cathode and the organic semiconductor to form a multilayer structure; the material with a high dielectric constant can also be called an electron injection material, and can be an alkali metal or alkaline earth metal fluoride, as well as the corresponding oxide or carbonate (e.g., LiF, Li2O, BaF2, MgO, NaF, CsF, Cs2CO3, etc.) or lithium quinoline (LiQ).

[0054] Compared with the prior art, the present invention has the following beneficial effects: This invention designs the structure of carbazole compounds to prepare high-performance carbazole compounds. Using carbazole compounds as the main material of the light-emitting layer, the resulting organic electroluminescent devices have high current efficiency, long lifespan, and low driving voltage. Detailed Implementation

[0055] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0056] Preparation Example 1 This preparation provides intermediate P1-1 and its synthesis method, which is as follows: Under nitrogen atmosphere, toluene (80 mL), ethanol (30 mL), water (15 mL), intermediate M0 (3.5 g), intermediate M1 (4.0 g), sodium carbonate (2.12 g), and tetraphenylphosphine palladium (0.23 g) were added to a three-necked flask. The mixture was slowly heated to reflux and reacted for 8 h. After cooling to room temperature, water and toluene were added and the mixture was separated. The organic layer was washed with water and dried with magnesium sulfate. After removing the desiccant, the mixture was concentrated to dryness and crystallized with toluene to obtain intermediate 1-1 (3.6 g).

[0057] The obtained intermediate 1-1 was subjected to mass spectrometry analysis, and the mass-to-charge ratio (m / z) was measured to be 552.12.

[0058] Preparation Examples 2-3 Preparation Examples 2-3 respectively provide an intermediate and its synthesis method. The synthesis method of the corresponding intermediate is the same as that of intermediate 1-1. The corresponding starting material 1 and starting material 2 are reacted to prepare the corresponding intermediate (as shown in Table 1 below). The mass spectra of the prepared intermediates are measured and the m / z is recorded. See Table 1 below for details: Table 1 Preparation Example 4 This preparation provides intermediate P15-1 and its synthesis method, which is as follows: Under a nitrogen atmosphere, 90 mL of toluene, 30 mL of ethanol, and 15 mL of water were added to a three-necked flask. Then, 5.5 g of intermediate P1-1, 1.3 g of phenylboronic acid, 2.12 g of sodium carbonate, and 0.2 g of dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium(II) (CAS No. 887919-35-9) were added. The mixture was slowly heated to reflux and reacted for 8 hours. After cooling to room temperature, water was added to separate the organic layer. The organic layer was washed with water and dried with magnesium sulfate. After removing the desiccant, the mixture was concentrated to dryness and separated by silica gel column chromatography. The elution was performed with petroleum ether:ethyl acetate = 10:3 (volume ratio) to obtain intermediate P15-1 (6.9 g).

[0059] The obtained intermediate P15-1 was analyzed by mass spectrometry, and the mass-to-charge ratio (m / z) was found to be 594.19.

[0060] Preparation Example 5 This preparation provides intermediate P16-1 and its synthesis method, which is as follows: Intermediate P16-1 was prepared by referring to the synthesis method of intermediate P15-1.

[0061] The obtained intermediate P16-1 was subjected to mass spectrometry analysis, and the mass-to-charge ratio (m / z) was measured to be 670.22.

[0062] Example 1 This embodiment provides compound P1 and its synthesis method, which is as follows: Following the preparation method of intermediate P15-1 and based on common knowledge, the amounts of reactants, reagents, and solvents were adjusted to prepare compound P1.

[0063] Mass spectrometry analysis of compound P1 showed a mass-to-charge ratio (m / z) of 636.26.

[0064] Examples 2-5 Examples 2-5 respectively provide a carbazole compound and its synthesis method. The synthesis method of the corresponding carbazole compound is the same as that of compound P1. Based on common knowledge, the amounts of reactants, reagents and solvents are adjusted to prepare the corresponding carbazole compounds (as shown in Table 2 below). The mass spectra of the prepared compounds are measured and the m / z is recorded. See Table 2 below for details: Table 2 Other compounds not listed can be synthesized by referring to the above examples and combining them with common knowledge in the art.

[0065] The specific structures of some of the compounds used in the following application examples and comparative application examples are as follows: , , , , , , , , , , , , , , , , , , , , , , .

[0066] Application Example 1 This application example provides a blue organic electroluminescent device, using compound P1 provided by the present invention as the host material of the light-emitting layer. The structure of the blue organic electroluminescent device is as follows: ITO / HT-1: HI-2[5%](80nm) / HT-1(30nm) / EB-1(20nm) / Main material: PBD-1[5%](35nm) / ETL-1(25 nm) / LiF(0.5nm) / Al(150 nm).

[0067] The fabrication method of the blue organic electroluminescent device is as follows: The material was placed inside a vacuum chamber, and the vacuum was evacuated to 1×10⁻⁶. -5 ~1×10 -6 Pa, the above materials are sequentially vacuum-deposited onto the cleaned ITO substrate to prepare OLED devices.

[0068] 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, HT-1 is the hole transport material; HT-1:HI-2[5%] is used as the hole injection layer material, and EB-1 is the electron blocking layer material.

[0069] Application Examples 2-4 Application Examples 2-4 each provide a blue organic electroluminescent device. The only difference from Application Example 1 is that the host material compound P1 of the light-emitting layer is replaced with other compounds (see Table 3 below). The other preparation steps and conditions are the same as in Application Example 1.

[0070] Comparative Application Examples 1-3 Comparative Application Examples 1-3 provide a blue organic electroluminescent device. The only difference from Application Example 1 is that the host material compound P1 of the light-emitting layer is replaced with other compounds (see Table 3 below). The other preparation steps and conditions are the same as in Application Example 1.

[0071] Performance testing The luminance, driving voltage, current efficiency, and LT95 of the organic electroluminescent devices provided above were tested. The current efficiency was measured at a luminance of 1000 cd / m². 2 The corresponding value, LT95, refers to maintaining an initial device current density of 10 mA / cm². 2 The time required for the device efficiency to drop to 95% of the efficiency corresponding to the initial current density, while remaining constant, is given. The drive voltage, current efficiency, and LT95 are relative values. Specific test results are shown in Table 3 below. Table 3 Application Examples 5-7 Application Examples 5-7 each provide a blue organic electroluminescent device. The only difference from Application Example 1 is that the host material compound P1 of the light-emitting layer is replaced with other compounds (see Table 4 below). The other preparation steps and conditions are the same as in Application Example 1.

[0072] Performance testing The luminance, driving voltage, current efficiency, and LT95 of the organic electroluminescent devices provided above were tested. The current efficiency was measured at a luminance of 1000 cd / m². 2 The corresponding value, LT95, refers to maintaining an initial device current density of 10 mA / cm². 2 The time required for the device efficiency to drop to 95% of the efficiency corresponding to the initial current density, while remaining constant, is given. The drive voltage, current efficiency, and LT95 are relative values. Specific test results are shown in Table 4 below. Table 4 Application Examples 8-10 Application Examples 8-10 each provide a blue organic electroluminescent device. The only difference from Application Example 1 is that the host material compound P1 of the light-emitting layer is replaced with other compounds (see Table 5 below), and PBD-1 is replaced with PBD-2. The other preparation steps and conditions are the same as in Application Example 1.

[0073] Performance testing The luminance, driving voltage, current efficiency, and LT95 of the organic electroluminescent devices provided above were tested. The current efficiency was measured at a luminance of 1000 cd / m². 2 The corresponding value, LT95, refers to maintaining an initial device current density of 10 mA / cm². 2 The time required for the device efficiency to drop to 95% of the efficiency corresponding to the initial current density, while remaining constant, is given. The drive voltage, current efficiency, and LT95 are relative values. Specific test results are shown in Table 5 below. Table 5 Application Examples 11-13 Application Examples 11-13 each provide a blue organic electroluminescent device. The only difference from Application Example 1 is that the host material compound P1 of the light-emitting layer is replaced with other compounds (see Table 6 below), and PBD-1 is replaced with PBD-2. The other preparation steps and conditions are the same as in Application Example 1.

[0074] Performance testing The luminance, driving voltage, current efficiency, and LT95 of the organic electroluminescent devices provided above were tested. The current efficiency was measured at a luminance of 1000 cd / m². 2 The corresponding value, LT95, refers to maintaining an initial device current density of 10 mA / cm². 2 The time required for the device efficiency to drop to 95% of the efficiency corresponding to the initial current density, while remaining constant, is given. The drive voltage, current efficiency, and LT95 are relative values. Specific test results are shown in Table 6 below. Table 6 In summary, this invention has prepared high-performance carbazole compounds by designing their structures. As the main material for the light-emitting layer, the organic electroluminescent devices prepared by these carbazole compounds have high current efficiency, long lifespan, and low driving voltage.

[0075] The applicant declares that the detailed process flow of this invention is illustrated by the above embodiments, but this invention is not limited to the above detailed process flow, that is, it does not mean that this invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A carbazole compound, characterized in that, The carbazole compounds have the structure shown in Formula I: Equation I; Among them, R1, R2, R3, and R4 are each independently selected from one of C6-C20 aryl and C3-C20 heteroaryl, and the linkage site of the C3-C20 heteroaryl is the carbon atom in the C3-C20 heteroaryl. In the compound of Formula I, each hydrogen atom can be independently substituted by at least one of the following: deuterium atom, -F, -CN, C1-C12 straight-chain or branched alkyl group, C3-C12 cycloalkyl group, C1-C12 alkoxy group, triphenylsilyl group, triphenylmethyl group, C6-C20 aryl group, and C3-C20 heteroaryl group.

2. The carbazole compound according to claim 1, characterized in that, The C1-C12 straight-chain or branched alkyl group is selected from any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, and n-undecyl. Preferably, the C3-C12 cycloalkyl group is selected from any one of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or adamantyl; Preferably, the alkoxy group of C1-C12 is selected from any one of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, cyclopentoxy, n-hexoxy, or cyclohexoxy. Preferably, the aryl group of C6-C20 is selected from any one of phenyl, naphthyl, biphenyl, terphenyl, 9,9-dimethylfluorenyl, triphenylene, anthracene, phenanthrene, or fluoranthyl. Preferably, the heteroaryl group of C3-C20 is selected from any one of triazinyl, carbazoleyl, dibenzofuranyl, dibenzothiophenyl, naphthobenzofuranyl or naphthobenzothiophenyl.

3. The carbazole compound according to claim 1 or 2, characterized in that, R1 and R2 are each independently selected from aryl groups of C6-C20; Preferably, R1 and R2 are each independently selected from any one of phenyl, naphthyl, biphenyl, terphenyl, and 9,9-dimethylfluorenyl, and more preferably any one of phenyl, biphenyl, and naphthyl; Preferably, R3 and R4 are each independently selected from any one of phenyl, naphthyl, biphenyl, terphenyl, 9,9-dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, and carbazoleyl.

4. The carbazole compound according to any one of claims 1-3, characterized in that, The hydrogen atoms in the compound of Formula I can each be independently replaced by any one of the following: deuterium, -F, -CN, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclopentyl, cyclohexyl, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, n-hexoxy, phenyl, naphthyl, and biphenyl.

5. The carbazole compound according to any one of claims 1-4, characterized in that, The carbazole compounds are selected from the following substituted or unsubstituted compounds: ； The substitution refers to the independent replacement of each hydrogen atom in the carbazole compound by a deuterium atom.

6. The carbazole compound according to any one of claims 1-5, characterized in that, The carbazole compound is selected from any one of the following compounds: 、 、 、 、 、 、 、 、 、 、 、 。 7. An intermediate, characterized in that, The intermediate has the structures shown in formulas MA and MB: 、 ； Among them, X1 and X2 are each independently selected from any one of -F, -Cl, -Br or -I; R1, R2, R3, and R4 have the same definitions as in claim 1; In the compounds of formula MA and formula MB, the hydrogen atoms can be independently substituted by at least one of the following: a deuterium atom, -F, -CN, C1-C12 alkyl, C1-C12 alkoxy, triphenylsilyl, triphenylmethyl, C6-C20 aryl, or C3-C20 heteroaryl.

8. The intermediate according to claim 7, characterized in that, The intermediate includes the following compounds: 、 、 、 、 。 9. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode; The material of the organic thin film layer includes carbazole compounds as described in any one of claims 1-6.

10. The organic electroluminescent device according to claim 9, characterized in that, The organic thin film layer includes a light-emitting layer, and the main material of the light-emitting layer includes a carbazole compound as described in any one of claims 1-6; Preferably, the light-emitting layer is a phosphorescent light-emitting layer; Preferably, the organic electroluminescent device is a blue organic electroluminescent device.

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