A dialkyl-substituted carbazole compound and an organic electroluminescent device

Abstract

The present application provides a kind of dialkyl-substituted carbazole compound and organic electroluminescent device.The dialkyl-substituted carbazole compound has the structure shown in formula I.The present application is designed by dialkyl-substituted carbazole compound, and excellent performance dialkyl-substituted carbazole compound is prepared, and thus the organic electroluminescent device prepared by dialkyl-substituted carbazole compound as the material of electron blocking layer has higher current efficiency and longer life.

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescent materials technology, specifically relating to a dialkyl-substituted carbazole compound 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] To address the shortcomings of existing technologies, the present invention aims to provide a dialkyl-substituted carbazole compound and an organic electroluminescent device. Through the design of dialkyl-substituted carbazole compounds, the present invention prepares high-performance dialkyl-substituted carbazole compounds. Organic electroluminescent devices prepared using these dialkyl-substituted carbazole compounds as electron blocking layer materials exhibit high current efficiency and long lifetime.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a dialkyl-substituted carbazole compound having the structure shown in Formula I:

[0007]

[0008] In this context, R1 and R2 each independently represent C1-C10 alkyl groups;

[0009] Ring A and ring B each independently represent either a benzene ring or a naphthalene ring;

[0010] Ar 601 Indicates C6-C20 aryl groups;

[0011] n represents 0 or 1, m represents 0 or 1;

[0012] Dashed lines indicate single bonds or absence of bonds;

[0013] In the compound of formula I shown, each hydrogen atom can be independently replaced by a deuterium atom (D);

[0014] The compounds of Formula I do not include compounds D1 and D5:

[0015]

[0016] This invention designs and prepares high-performance dialkyl-substituted carbazole compounds. These compounds have suitable HOMO and LUMO energy levels, good molecular film-forming properties, and strong charge transport capabilities. Organic electroluminescent devices prepared using these dialkyl-substituted carbazole compounds as electron blocking layer materials exhibit high current efficiency and long lifetime.

[0017] In this invention, C1-C10 can be C1, C2, C3, C4, C5, C6, C7, C8, C9 or C10.

[0018] C6-C20 can be C6, C8, C10, C12, C15, C18 or C20.

[0019] In this invention, "D" represents a deuterium atom, and the same applies below.

[0020] 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.

[0021] As a preferred embodiment of the present invention, R1 and R2 each independently represent any one of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl or decyl, and are further preferably any one of methyl, isopropyl, tert-butyl, methylcyclopentyl, methylcyclohexyl, adamantyl, bicyclo[2.2.1]heptyl or bicyclo[2.2.2]octyl.

[0022] As a preferred technical solution of the present invention, the Ar 601 It represents any one of phenylene, naphthylene, or biphenylene.

[0023] In a preferred embodiment of the present invention, both ring A and ring B represent benzene rings.

[0024] As a preferred embodiment of the present invention, one of ring A and ring B is a benzene ring and the other is a naphthalene ring.

[0025] In a preferred embodiment of the present invention, m represents 1 and n represents 0.

[0026] In a preferred embodiment of the present invention, m represents 1 and n represents 1.

[0027] As a preferred embodiment of the present invention, the compound of formula I is selected from any one of the following substituted or unsubstituted compounds P1 to P66:

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] The substitution refers to the independent replacement of hydrogen atoms in compounds P1 to P66 by deuterium atoms.

[0034] Preferably, the compound of formula I is selected from any one of the following compounds:

[0035]

[0036]

[0037] In this invention, there are no special restrictions on the preparation method of the compound of formula I, and all commonly used preparation methods in the art are applicable;

[0038] When m = 1 and n = 0, compound I has the structure shown in formula I-1:

[0039]

[0040] The first synthetic method for compound I-1 is as follows:

[0041]

[0042] Among them, R1, R2, ring A, and ring B have the same protection range as those mentioned above;

[0043] Dashed lines indicate single keys or non-existent keys;

[0044] X, Y, and Z each independently represent a halogen atom (e.g., F, Cl, Br, or I).

[0045] The specific reaction steps are as follows:

[0046] (1) M1-1-1 and M1-1-2 react to produce M1-1-3;

[0047] (2) M1-1-3 undergoes a halogenation reaction to generate I-1-0;

[0048] (3) The compound shown in I-1-0 first reacts with butyllithium, and then with... The reaction produces the intermediate shown in I-1-a;

[0049] (4) The intermediate shown in I-1-a first reacts with butyllithium, and then with... The reaction produces the compound shown in 1-1.

[0050] Of course, in the above synthesis method, the butyllithium in step (3) can be replaced with other alkyl lithium salts, or dialkylamino lithium (e.g., diisopropylamino lithium), and the compound shown in formula I-1 can also be prepared.

[0051] It should also be noted that the present invention does not impose any special restrictions on the specific process conditions in steps (1) to (4), and can be designed according to the preparation methods in the field.

[0052] In a second aspect, the present invention also provides an intermediate comprising the following compounds:

[0053]

[0054] Among them, R1, R2, ring A, and ring B have the same protection range as described above;

[0055] Dashed lines indicate single keys or non-existent keys;

[0056] X and Y each represent halogen atoms independently;

[0057] The intermediate is used to prepare dialkyl-substituted carbazole compounds as described in the first aspect.

[0058] Preferably, the intermediate comprises the following compounds:

[0059]

[0060] Thirdly, 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;

[0061] The organic thin film layer includes the dialkyl-substituted carbazole compounds described in the first aspect.

[0062] As a preferred embodiment of the present invention, the organic thin film layer includes a hole layer, which includes a hole injection layer, a hole transport layer, and an electron blocking layer.

[0063] Preferably, the organic thin film layer comprises an electron blocking layer and a light-emitting layer, wherein the electron blocking layer is made of a dialkyl-substituted carbazole compound as described in the first aspect.

[0064] Preferably, the light-emitting layer is a phosphorescent light-emitting layer.

[0065] As a preferred embodiment of the present invention, the organic electroluminescent device is a blue organic electroluminescent device.

[0066] In this invention, the light-emitting layer includes a main material and a dopant material. The dopant material is also called a dye or a phosphorescent material. The main material of the light-emitting layer can be a single compound or a mixture of two or more compounds.

[0067] 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.

[0068] 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%.

[0069] 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 light emitted by a substance from a triplet excited state. In this invention, the specific selection of the phosphorescent material 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 the structure shown in formula PD.

[0070]

[0071] Wherein, M is selected from any one of Ir, Pt, Pd, Os, Ti, Zr, Hf, Eu, Tb, Tm, Cu or Au;

[0072] Y1-Y4 are each independently selected from carbon or nitrogen;

[0073] 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.

[0074] 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;

[0075] 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.

[0076] 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., C2, C3, C4, C5, C6, C7, C8, C9, or C10), heterocyclic alkyl, substituted or unsubstituted C6-C60 (e.g., 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.

[0077] a1 and a2 are each independent integers selected from 1 to 5, for example, they can be 1, 2, 3, 4 or 5;

[0078] b is an integer selected from 0 to 4, for example, it can be 0, 1, 2, 3 or 4;

[0079] a is selected from 1, 2, or 3;

[0080] L1 can be a monovalent organic ligand, a divalent organic ligand, or a trivalent organic ligand.

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

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] In this invention, the hole layer material (including the hole injection layer, the hole transport layer, and the electron blocking layer) can also have the structure shown in the following formula HT-GH4:

[0089]

[0090] 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;

[0091] Ar 41 Ar 42 Each is independently selected from C6-C40 (e.g., C6, C8, C10, C12, C16, C20, C24, C28, C30, C32, C36, or C40, etc.) aryl groups and C6-C20 (e.g., C6, C8, C10, C12, C16, or C20, etc.) heteroaryl groups;

[0092] X is selected from CR 41 R 42 Or NR 43 , where R 41 R 42 R 43 Each is independently selected from any one of 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 dibenzothiophene (the substituent is phenyl), dibenzofuran-substituted thiophene, C1-C6 (e.g., C1, C2, C3, C4, C5, or C6) alkyl groups, R 41 R 42 They can be connected into a ring using a single key.

[0093] Preferably, the compound of formula HT-GH4 is selected from any one of the following compounds:

[0094]

[0095]

[0096]

[0097]

[0098]

[0099] 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.

[0100] 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-phenanthroline, N-carbazole, N-dibenzofuran, and N-dibenzothiophene.

[0101] In this invention, no special restrictions are placed on the electron transport layer material, and exemplary structures include, but are not limited to, the following:

[0102]

[0103] 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.

[0104] 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).

[0105] Compared with the prior art, the present invention has the following beneficial effects:

[0106] This invention designs the structure of dialkyl-substituted carbazole compounds to make them suitable as electron blocking layer materials for organic electroluminescent devices. The organic electroluminescent devices prepared in this way have high current efficiency and long service life. Detailed Implementation

[0107] 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.

[0108] Preparation Example 1

[0109] This preparation example provides the intermediate M5-0Br and its synthesis method, which is as follows:

[0110]

[0111] Under nitrogen protection, 200 mL of dichloromethane and 15 g of bromobenzene were added to a 1000 mL three-necked flask. 40 g of anhydrous aluminum trichloride was slowly added, and the temperature was lowered to 0-5 °C. A 100 mL solution of 15 g of cyclohexene in dichloromethane was slowly added dropwise. After the addition was complete, the mixture was kept at 0-5 °C for 2 hours, then allowed to react at room temperature for another 2 hours. After the reaction was complete, the temperature was lowered, dilute hydrochloric acid was added, and the mixture was separated. The organic layer was washed twice with water, dried, and concentrated under reduced pressure to obtain crude dicyclopentylbromobenzene. GC (gas chromatography) analysis showed that the crude dicyclopentylbromobenzene contained […].

[0112] The crude dicyclopentylbromobenzene was added to a 250 mL three-necked flask, along with 100 mL of nitrobenzene and 10 g of anhydrous aluminum trichloride. The mixture was heated to 100 °C and stirred for 12 hours. After cooling, dilute hydrochloric acid was added, and the mixture was separated. The organic layer was washed twice with water, dried, and concentrated under reduced pressure to obtain dicyclopentylbromobenzene. GC analysis showed that it contained […]. The intermediate M5-0Br was then separated by silica gel column chromatography and eluted with petroleum ether to obtain 16.1 g of the intermediate. GC analysis showed that the content of dicyclopentylbromobenzene was 99.2%.

[0113] The intermediate M5-0Br was analyzed by mass spectrometry, and the two peaks with the largest m / z were 292.08 and 294.08.

[0114] The intermediate M5-0Br was subjected to NMR analysis, and the data are as follows: 1H-NMR (Bruker, Switzerland, Avance II 400MHz NMR spectrometer, CDCl3), δ7.30 (d, 2H), δ7.11 (t, 1H), δ2.57 (m, 2H), δ2.10-1.65 (m, 16H).

[0115] Preparation Example 2

[0116] This preparation example provides the intermediate M6-0Br and its synthesis method, which is as follows:

[0117]

[0118] The specific preparation steps are the same as those for the synthesis of intermediate M5-0Br provided in Preparation Example 1, and M6-0Br is prepared.

[0119] The intermediate M6-0Br was analyzed by mass spectrometry, and the two peaks with the largest m / z were 320.11 and 322.11.

[0120] Preparation Example 3

[0121] This preparation example provides the intermediate M7-0Br and its synthesis method, which is as follows:

[0122]

[0123] Under nitrogen protection, 400 mL of dichloromethane and 15 g of bromobenzene were added to a 1000 mL three-necked flask. Then, 30 g of 98% sulfuric acid was slowly added. The temperature was lowered to 0-5 °C, and a 100 mL dichloromethane solution containing 22 g of 1-methylcyclopentanol was slowly added dropwise. After the addition was complete, the mixture was kept at 0-5 °C for 2 hours, then allowed to react at room temperature for another 2 hours. After the reaction was complete, the temperature was lowered, water was added, and the mixture was separated. The organic layer was washed twice with water, dried, and concentrated under reduced pressure to obtain crude di(1-methylcyclopentyl)bromobenzene. GC analysis showed that the crude di(1-methylcyclopentyl)bromobenzene contained […].

[0124] The crude di(1-methylcyclopentyl)bromobenzene was added to a 250 mL three-necked flask, along with 100 mL of nitrobenzene and 10 g of anhydrous aluminum trichloride. The mixture was heated to 100 °C and stirred for 12 hours. After cooling, dilute hydrochloric acid was added, and the mixture was separated. The organic layer was washed twice with water, dried, and concentrated under reduced pressure to obtain di(1-methylcyclopentyl)bromobenzene. GC analysis confirmed that it contained […]. The intermediate M7-0Br was then separated by silica gel column chromatography and eluted with petroleum ether, yielding 13.8 g of the intermediate. GC analysis showed that the content of di(1-methylcyclopentyl)bromobenzene was 99.3%.

[0125] The intermediate M7-0Br was analyzed by mass spectrometry, and the two peaks with the largest m / z were 320.11 and 322.11.

[0126] The intermediate M7-0Br was subjected to NMR analysis, and the data are as follows: 1H-NMR (Bruker, Switzerland, Avance II 400MHz NMR spectrometer, CDCl3), δ7.32 (t, 1H), δ7.24 (d, 2H), δ2.07-1.62 (m, 16H), δ1.33 (s, 6H).

[0127] Preparation Example 4

[0128] This preparation example provides the intermediate M8-0Br and its synthesis method, which is as follows:

[0129]

[0130] The specific preparation steps are the same as those provided in Preparation Example 3, which is used to synthesize intermediate M7-0Br, and M8-0Br is prepared.

[0131] The intermediate M8-0Br was analyzed by mass spectrometry, and the two peaks with the largest m / z were 348.15 and 350.14.

[0132] Preparation Example 5

[0133] This preparation example provides intermediate M1-0 and its synthesis method, which is as follows:

[0134]

[0135] Under nitrogen protection, dry toluene (70 mL), 3,4-di-tert-butylbromobenzene (2.7 g), carbazole (1.7 g), Pd(dba)2 (bis(dibenzylacetone palladium, 0.0575 g), a 10% (w / w) solution of tri-tert-butylphosphine toluene (0.4 g) and sodium tert-butoxide (1.44 g) were added to a 250 mL three-necked flask. The mixture was heated to reflux for 8 h, cooled to room temperature, and water was added to dissolve the mixture. The organic layer was then washed with water until neutral, dried with magnesium sulfate, filtered to remove magnesium sulfate, concentrated to dryness, and crystallized with ethanol to obtain intermediate M1-0 (2.8 g).

[0136] Mass spectrometry analysis of intermediate M1-0 revealed a mass-to-charge ratio (m / z) of 355.23.

[0137] Intermediate preparation examples 6-13

[0138] Examples 6-13 each describe the preparation of an intermediate (see Table 1 below). The synthesis method of the intermediate is the same as that of intermediate M1-0 provided in Example 5, except that different raw materials are used (see Table 1 below).

[0139] Table 1

[0140]

[0141]

[0142] Preparation Example 14

[0143] This preparation example provides intermediate M1 and its synthesis method, which is as follows:

[0144]

[0145] Under nitrogen protection, 3.6 g of intermediate M1-0 and 50 mL of DMF were added to a 500 mL three-necked flask. 3.7 g of solid NBS (N-bromosuccinimide) was added in portions at 20-25 °C. After the addition was complete, the mixture was stirred at 20-25 °C for 8 hours. Water was added, and the solid was filtered. After drying, it was crystallized from ethanol to obtain 4.7 g of intermediate M1.

[0146] Mass spectrometry analysis of intermediate M1 revealed that the peak with the largest mass-to-charge ratio (m / z) was 513.05, with an abundance of 100%. Other peaks at m / z were 511.05 and 515.05, with abundances of approximately 50%.

[0147] Preparation Examples 15-23

[0148] Preparation Examples 15-23 each provide an intermediate (see Table 2 below). The synthesis method of the intermediate is the same as that of intermediate M1 provided in Preparation Example 14, except that different raw materials are used (see Table 2 below).

[0149] Table 2

[0150]

[0151]

[0152] The intermediate M9 was analyzed by NMR, and the data are as follows: 1H-NMR (Bruker, Switzerland, Avance II 400MHz NMR spectrometer, CDCl3), δ8.09 (s, 1H), δ8.05 (d, 1H), δ7.88 (m, 2H), δ7.60 (d, 1H), δ7.50~7.40 (m, 4H), δ7.38 (d, 1H), δ7.10 (m, 1H), δ2.26 (s, 3H), δ1.33 (s, 9H).

[0153] Preparation Example 24

[0154] This preparation example provides intermediate M1-2 and its synthesis method, which is as follows:

[0155]

[0156] Under nitrogen protection, 0.01 mol of intermediate M1 and 200 mL of tetrahydrofuran were added to a 500 mL three-necked flask. The temperature was then lowered to -78 °C, and a hexane solution (1.6 M, 6.25 mL) containing 0.01 mol of butyllithium was slowly added. The mixture was then kept at -78 °C to -60 °C for 30 min. A solution of 0.012 mol of triphenylchlorosilane and 20 mL of tetrahydrofuran, 0.0001 mol of Pd(dba)2, and 0.0001 mol of anhydrous nickel chloride were added. The mixture was slowly heated to room temperature and reacted for 2 hours, then heated to reflux and reacted for another 2 hours. The mixture was then cooled, and water and toluene were added to separate the layers. The organic layer was washed with water until neutral, dried over anhydrous magnesium sulfate, and the desiccant was removed. The mixture was then concentrated to dryness and separated by silica gel column chromatography. Elution was performed using petroleum ether:ethyl acetate = 20:1 (v / v) to give intermediate M1-2 (5.6 g).

[0157] The obtained intermediate M1-2 was analyzed by mass spectrometry. The two peaks with the largest m / z values ​​were 693.22 and 691.23, and their abundances were basically the same.

[0158] Preparation Examples 25-27

[0159] Preparation Examples 25-27 each provide an intermediate (see Table 3 below). The synthesis method of the intermediate is the same as that of the reference intermediate M1-2 provided in Preparation Example 24, except that different raw materials are used (see Table 3 below).

[0160] Table 3

[0161]

[0162] Synthesis Example 1

[0163] This synthetic example provides compound P1 and its synthetic method, which is as follows:

[0164]

[0165] Under nitrogen protection, 0.01 mol of intermediate M1 and 200 mL of tetrahydrofuran were added to a 500 mL three-necked flask. The temperature was then lowered to -78 °C, and a hexane solution containing 0.022 mol of butyllithium (1.6 M, 13.8 mL) was slowly added. The mixture was then kept at -78 °C to -60 °C for 30 min. A solution of 0.022 mol of triphenylchlorosilane and 30 mL of tetrahydrofuran, 0.0002 mol of Pd(dba)2, and 0.0002 mol of anhydrous nickel chloride were added. The mixture was slowly heated to room temperature and reacted for 2 hours, then heated to reflux temperature and reacted for another 2 hours. The mixture was then cooled, and water and toluene were added to separate the layers. The organic layer was washed with water until neutral, dried over anhydrous magnesium sulfate, and the desiccant was removed. The mixture was then concentrated to dryness and separated by silica gel column chromatography. The eluent was 20:1 (v / v) of petroleum ether and ethyl acetate to give compound P1 (6.9 g).

[0166] The obtained compound P1 was analyzed by mass spectrometry, and the mass-to-charge ratio (m / z) was measured to be 871.40.

[0167] Synthesis Examples 2-7

[0168] Synthesis Examples 2-7 each describe a compound (see Table 4 below). The synthesis methods of the compounds are the same as those of compound P1 provided in Synthesis Example 1, except that M1 is replaced with other corresponding brominated derivatives and triphenylchlorosilane is replaced with other corresponding chlorinated derivatives. The obtained compounds were analyzed by mass spectrometry, and their mass-to-charge ratio data are shown in Table 4 below.

[0169] Table 4

[0170]

[0171]

[0172] Synthesis Example 8

[0173] This synthetic example provides compound P2 and its synthetic method, which is as follows:

[0174]

[0175] Under nitrogen protection, 0.01 mol of M1-2 intermediate and 300 mL of tetrahydrofuran were added to a 500 mL three-necked flask. The temperature was then lowered to -78 °C, and a hexane solution (1.6 M, 6.25 mL) containing 0.01 mol of butyllithium was slowly added. The temperature was then maintained at -78 °C to -60 °C for 30 min, and 0.012 mol of... A solution prepared with 20 mL of tetrahydrofuran, 0.0001 mol Pd(dba)2, and 0.0001 mol anhydrous nickel chloride was slowly heated to room temperature and reacted for 2 hours. The temperature was then raised to reflux temperature and reacted for another 2 hours. The mixture was cooled, and water and toluene were added to separate the layers. The organic layer was washed with water until neutral, dried over anhydrous magnesium sulfate, and the desiccant was removed. The mixture was then concentrated to dryness and separated by silica gel column chromatography. Elution was performed using petroleum ether:ethyl acetate = 20:1 (v / v) to give compound P2 (6.6 g).

[0176] The obtained compound P2 was analyzed by mass spectrometry, and the mass-to-charge ratio (m / z) was found to be 869.39.

[0177] Synthesis Examples 9-11

[0178] Synthesis Examples 9-11 each provide a compound (see Table 5 below for details). The synthesis method of the compound is the same as that of compound P2 provided in Synthesis Example 8, except that M1-2 are replaced with other corresponding brominated compounds. The obtained compounds are analyzed by mass spectrometry, and their mass-to-charge ratio data are shown in Table 5 below.

[0179] Table 5

[0180]

[0181] Synthesis Example 12

[0182] This synthetic example provides compound P34 and its synthetic method, which is as follows:

[0183]

[0184] Under nitrogen protection, 120 mL of toluene, 50 mL of ethanol, and 20 mL of water were added sequentially to a 500 mL three-necked flask. Then, 0.01 mol of intermediate M1-2, 0.01 mol of triphenylsilylphenylboronic acid, 0.02 mol of sodium carbonate, and 0.0002 mol of tetraphenylphosphine palladium were added. The mixture was slowly heated to reflux temperature 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 with petroleum ether:ethyl acetate = 10:0.5 (v / v) to give compound P34 (6.2 g).

[0185] The obtained compound P34 was analyzed by mass spectrometry, and the mass-to-charge ratio (m / z) was found to be 947.43.

[0186] Synthesis Example 13

[0187] This synthetic example provides compound P41 and its synthetic method, which is as follows:

[0188]

[0189] The specific synthesis method is the same as that used in Example 12 for synthesizing compound P34, except that triphenylsilylphenylboronic acid is replaced with an equal amount of phenylboronic acid to obtain compound P41.

[0190] The obtained compound P41 was analyzed by mass spectrometry, and the mass-to-charge ratio (m / z) was found to be 689.35.

[0191] Synthesis Example 14

[0192] This synthetic example provides compound P40 and its synthetic method, which is as follows:

[0193]

[0194] Under nitrogen protection, 0.01 mol of intermediate M1-2 and 150 mL of tetrahydrofuran were added to a 500 mL three-necked flask. The temperature was then lowered to -78 °C, and a hexane solution containing 0.01 mol of butyllithium (1.6 M, 6.25 mL) was slowly added. The temperature was maintained at -78 °C to -60 °C for 30 min. 1 mL of ethanol was added, and the mixture was brought to room temperature. Water and toluene were added and the mixture was separated. The organic layer was washed with water until neutral, dried over anhydrous magnesium sulfate, filtered to remove the desiccant, concentrated to dryness, and crystallized from ethanol to obtain compound P40 (5.0 g).

[0195] The obtained compound P40 was detected by mass spectrometry, and the m / z was 613.32.

[0196] Compounds not listed above can be synthesized by referring to the above methods and combining them with common knowledge in the field.

[0197] The specific structures of some of the compounds used in the following application examples and comparative application examples are as follows:

[0198]

[0199]

[0200] Application Example 1

[0201] This application example provides a blue organic electroluminescent device, using compound P1 provided by the present invention as the electron blocking layer material. The structure of the blue organic electroluminescent device is as follows:

[0202] ITO / HT-1: HI-2[5%](80nm) / HT-1(30nm) / P1(20nm) / H1: PBD-1[5%](35nm) / ETL-1(25nm) / LiF(0.5nm) / Al(150nm).

[0203] The fabrication method of the blue organic electroluminescent device is as follows:

[0204] 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.

[0205] Wherein, 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. In this application example, the host material is H1; 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 to 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. The compound P1 of this invention forms an electron blocking layer.

[0206] Application Example 2-12

[0207] Application Examples 2-12 provide a blue organic electroluminescent device, which differs from Application Example 1 only in that the electron blocking layer material compound P1 is replaced with other compounds (see Table 6 below). The other preparation steps and conditions are the same as in Application Example 1.

[0208] Comparative Application Examples 1-3

[0209] Comparative Application Examples 1-3 provide an organic electroluminescent device, the only difference from Application Example 1 is that the electron blocking layer material compound P1 is replaced with other compounds (see Table 6 below), and the other preparation steps and conditions are the same as in Application Example 1.

[0210] Performance testing

[0211] The luminance, driving voltage, current efficiency, and LT95 of the organic electroluminescent devices provided in the above application examples or comparative application examples were tested. The current efficiency is calculated when the luminance is 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 used. Here, current efficiency and LT95 are relative values. Specific test results are shown in Table 6 below:

[0212] Table 6

[0213]

[0214]

[0215] As can be seen from the above, the present invention designs the structure of dialkyl-substituted carbazole compounds to make them suitable as electron blocking layer materials for organic electroluminescent devices. The organic electroluminescent devices prepared in this way have high current efficiency and long service life.

[0216] Application Examples 13-18, Comparative Application Examples 4-5

[0217] Application Examples 13-18 and Comparative Application Examples 4-5 each provide a blue organic electroluminescent device. The only difference from Application Example 1 is that the main material is H2, and the electron blocking layer material compound P1 is replaced with other compounds (see Table 7 below). The other preparation steps and conditions are the same as in Application Example 1.

[0218] The luminance, driving voltage, current efficiency, and LT95 of the organic electroluminescent devices provided in the above application examples or comparative application examples were tested. The current efficiency is calculated when the luminance is 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 used. Here, current efficiency and LT95 are relative values. Specific test results are shown in Table 7 below:

[0219] Table 7

[0220] Application Example 13 P34 1000 1 1 Application Example 14 P40 1000 2.09 1.88 Application Example 15 P41 1000 1.87 2.02 Application Example 16 P48 1000 1.79 2.55 Application Example 17 P17 1000 1.17 1.29 Application Example 18 P8 1000 1.09 1.22 Comparative Application Example 4 D1 1000 0.34 0.57 Comparative Application Example 5 D4 1000 0.87 0.76

[0221] As can be seen from the above, the present invention designs the structure of dialkyl-substituted carbazole compounds to make them suitable as electron blocking layer materials for organic electroluminescent devices. The organic electroluminescent devices prepared in this way have high current efficiency and long service life.

[0222] 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 dialkyl-substituted carbazole compound, characterized in that, The dialkyl-substituted carbazole compound is selected from any one of the following substituted or unsubstituted compounds: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 ； The substitution refers to the fact that each hydrogen atom in the above compound can be independently replaced by a deuterium atom.

2. 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 organic thin film layer includes the dialkyl-substituted carbazole compound as described in claim 1.

3. The organic electroluminescent device according to claim 2, characterized in that, The organic thin film layer includes an electron blocking layer and a light-emitting layer, wherein the electron blocking layer is made of a dialkyl-substituted carbazole compound as described in claim 1.

4. The organic electroluminescent device according to claim 3, characterized in that, The light-emitting layer is a phosphorescent light-emitting layer.

5. The organic electroluminescent device according to claim 2, characterized in that, The organic electroluminescent device is a blue organic electroluminescent device.

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