Carbazole fused ring compound and organic light-emitting device

Abstract

The invention belongs to the technical field of materials, and particularly relates to a carbazole fused ring compound and an organic light-emitting device. On the basis of an indolocarbazole structure, an alicyclic unit with a branch configuration is introduced, a mother nucleus structure with a more stable three-dimensional skeleton is constructed, and a novel electroluminescent material is formed. The organic compound has good stability and fluorescence efficiency, and when the organic compound is used as a luminescent layer of the organic electroluminescent device, the driving voltage of the organic electroluminescent device can be effectively reduced, the luminescent efficiency of the device can be improved, and the service life of the device can be prolonged.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, specifically relating to a carbazole fused-ring compound and an organic light-emitting device. Background Technology

[0002] Organic light-emitting devices (OLEDs) are core components of next-generation display and lighting technologies. Compared with traditional display technologies such as liquid crystal displays (LCDs), OLED devices have self-emissive properties, do not rely on backlights, and can achieve extremely thin and light device designs, with thicknesses reduced to the micrometer level. At the same time, OLEDs also have outstanding advantages such as high response speed, high contrast, flexibility, and low power consumption, and have been widely used in smartphones, smart wearable devices, televisions, automotive displays, and other fields.

[0003] As OLED applications continue to expand, the market is placing increasingly stringent standards and requirements on device performance. The emissive layer, as the core functional layer of an OLED device, directly determines the device's brightness, efficiency, lifetime, and color purity. The emissive layer typically consists of a host material and doped emissive materials (guest materials). The main function of the host material is to dissolve and disperse the guest material, preventing luminescence quenching due to guest material aggregation. Simultaneously, it enables the efficient transport, capture, and recombination of holes and electrons, providing energy to the guest material to excite its luminescence. However, current OLED host light-emitting materials still have many defects, making it difficult to meet the requirements of high-performance devices: First, poor charge transport balance, with most host materials tending to transport holes or electrons, causing the charge recombination region in the light-emitting layer to deviate from the interlayer interface, easily triggering exciton quenching and reducing device luminous efficiency; Second, insufficient thermal and morphological stability, with some host materials having low glass transition temperatures (Tg) (usually below 120℃), making them prone to crystallization or phase separation during device fabrication (such as evaporation and encapsulation) and long-term use, damaging the integrity of the light-emitting layer structure, leading to accelerated brightness decay and shortened lifespan; Third, low energy gap matching, for guest materials with specific emission wavelengths (especially deep blue or red guests), the highest occupied molecular orbital (HOMO) level and the lowest unoccupied molecular orbital (LUMO) level of existing host materials cannot achieve effective energy transfer, easily resulting in energy back-transfer or exciton leakage, leading to decreased device color purity and reduced efficiency. To address the issues of charge transport imbalance, poor thermal stability, and low energy matching in the existing OLED main light-emitting materials, it is necessary to continuously develop new materials for organic light-emitting devices. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a carbazole fused-ring compound and an organic light-emitting device.

[0005] The technical solution provided by this invention is as follows: A carbazole fused-ring compound having the structural formula shown in Formula 1: Any two adjacent bonds among X1, X2, X3, and X4 form The remainder are CH; L is selected from direct bonds, phenylene, or fused and aryl groups with 10-15 carbon atoms; A is selected from aryl groups with 6-30 carbon atoms (substituted or unsubstituted), arylamine groups with 6-30 carbon atoms (substituted or unsubstituted), or heteroaryl groups with 6-30 carbon atoms (substituted or unsubstituted).

[0006] In this invention, "substitution" means that the hydrogen atom on the compound group is replaced by another atom or group, and the substitution position is arbitrary; "unsubstitution" means that the hydrogen atom on the compound group is not replaced by another atom or group.

[0007] The first formula further has the structural formulas shown in formulas 1-1 to 1-3: .

[0008] Specifically, fused and aryl groups with 10-15 carbon atoms are aryl groups containing 2-3 phenyl groups.

[0009] Specifically, aryl groups with 6-30 carbon atoms are aromatic groups containing 2-4 phenyl groups, with the phenyl groups linked by single bonds, fused bonds, or a combination of both.

[0010] Specifically, the aromatic amino group with 6-30 carbon atoms is -NR1R2, where R1 and R2 are aromatic or heteroaromatic groups containing 2-4 phenyl groups, and the linkage between the phenyl groups is selected from any one or more combinations of single bond linkage, fused linkage, or heteroatom linkage.

[0011] Specifically, heteroaryl groups with 6-30 carbon atoms are heteroaryl groups containing 1-2 heteroatoms and 2-4 phenyl groups.

[0012] In the above technical solution, the substituents in the aryl group with 6-30 carbon atoms, the arylamine group with 6-30 carbon atoms, and the heteroaryl group with 6-30 carbon atoms are alkyl, cyano, or phenyl with 1-4 carbon atoms; the heteroatoms are O, S, or N.

[0013] Preferably, A is selected from , , , ; In formula A-1, R3-R7 are independently represented as H, cyano, hydroxyl, mercapto, or C, respectively. 1-4Alkyl groups, or those composed of cyano groups, C 1-4 Alkyl, phenyl-substituted or unsubstituted C 6-12 aryl, R 3-7 Any two adjacent groups can bond together to form a fused aromatic ring or a heteroaromatic ring; In formula A-2, n is selected from 0, 1, or 2, and each R8 is independently represented as a cyano group, C group, etc. 1-4 Alkyl groups, or those composed of cyano groups, C 1-4 Alkyl, phenyl-substituted or unsubstituted C 6-12 The aryl group, or the group consisting of cyano, C 1-4 Alkyl, phenyl-substituted or unsubstituted C 6-18 heteroaryl groups, R9 is represented by H, C 1-4 alkyl, C 6-12 The aryl group, or R9 is the linking site with L; R 10 -R 13 Each can be represented independently as the structure shown in A-1 or A-2; Z1-Z3 are each independently represented as N or CH, and at least one of them is N.

[0014] Preferred, C 6-12 The aryl group is selected from: phenyl, biphenyl, naphthyl; Preferred, C 6-12 The heteroaryl group is selected from: carbazolyl, dibenzofuranyl, and dibenzothiophenel.

[0015] Preferred, It has cyano, C 1-4 The alkyl, phenyl-substituted or unsubstituted compounds have the following structural formulas: , , ; Preferred, It has cyano, C 1-4 The alkyl, phenyl-substituted or unsubstituted compounds have the following structural formulas: , , , ; Z4 is selected from C(CH3)2, O, and S; Z5 is selected from C(CH3)2, O, S, and N-Ph.

[0016] Preferably, the fused and aryl groups having 10-15 carbon atoms are selected from any one of the following structural formulas: , .

[0017] The compound is any one of the following formulas 1-170: .

[0018] Generally, the carbazole fused-ring compounds provided by this invention can be prepared by methods similar to those described below: 1) and Prepared by electrophilic substitution reaction ; 2) Prepared by ring-closing reaction ; 3) and Electrophilic substitution reaction, or After the boric acid reaction occurs, it reacts with The halogenated derivatives were subjected to the Suzuki reaction to prepare a carbazole fused-ring compound with the structure of formula 1.

[0019] Secondly, this application provides an organic electroluminescent device, including a first electrode and a second electrode disposed opposite to each other, wherein an organic layer is disposed between the first electrode and the second electrode, and the organic layer includes any organic fused ring compound provided by this invention.

[0020] The organic layer includes any one, two or more of the following: a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, an electron blocking layer, a hole blocking layer, a light-emitting layer, and a light-emitting auxiliary layer. The organic layer containing an organic fused ring compound is a light-emitting layer, an electron transport layer, or a hole transport layer.

[0021] Any layer of organic material can be a single-layer structure composed of a single substance, or a single-layer or multi-layer structure composed of different substances.

[0022] Thirdly, the present invention provides an electronic device including the organic electroluminescent device described herein. The electronic device can be a display device, a lighting device, an optical communication device, or other types of electronic devices. For example, it can include a computer screen, a mobile phone screen, a television set, etc., but is not limited thereto.

[0023] This application, based on the indole-carbazole structure, introduces alicyclic units with branched configurations to construct a more stable three-dimensional core structure, achieving efficient balanced charge transport within the host material and improving charge recombination efficiency. Simultaneously, by introducing rigid large π-conjugated groups such as benzene rings to optimize the functional group composition in the molecular structure, the glass transition temperature and thermal decomposition temperature of the material are increased, enhancing its thermal and morphological stability and ensuring the structural integrity of the luminescent layer during device fabrication and long-term use. Furthermore, by precisely controlling molecular structural parameters, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the material are precisely controlled, achieving efficient energy matching with the energy levels of commonly used guest luminescent materials, avoiding energy back-transfer and exciton leakage, thereby significantly improving the luminous efficiency, color purity, brightness, and lifespan of OLED devices. Detailed Implementation

[0024] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0025] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0026] The halogenated or borated intermediates of the compounds provided in this invention can be prepared by the following methods: Specifically, taking the synthesis of borate intermediate D-1 as an example, the detailed steps are as follows: S1: In a round-bottom flask, add 300 mL of N,N-dimethylacetamide, raw material A-1 (27.74 g, 0.1 mol), raw material B-1 (23.04 g, 0.11 mol), and cesium carbonate (65.15 g, 0.2 mol). Stir and react under nitrogen protection at 150 °C for 16 h. After the reaction is complete, cool to room temperature, add 500 mL of deionized water to the reaction vessel, filter, add petroleum ether to the solid, slurry, filter, and obtain 33.60 g of intermediate a-1, yield 72%.

[0027] S2: In a round-bottom flask, intermediate a-1 (28.01 g, 60 mmol), K2CO3 (20.73 g, 150 mmol), tricyclohexylphosphine fluoroborate (1.1 g, 3 mmol), palladium acetate (0.34 g, 1.5 mmol), and 300 mL of N,N-dimethylacetamide were added sequentially. Under nitrogen protection, the mixture was heated to 120 °C and refluxed for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, and 500 mL of deionized water was added to the reaction vessel. The mixture was filtered, and the solid was crystallized by adding a mixed solvent of dichloromethane and petroleum ether. The crystals were filtered, dried, and 13.88 g of intermediate b-1 was obtained, with a yield of 60%.

[0028] S3: In a round-bottom flask, add 100 mL of tetrahydrofuran and intermediate b-1 (11.58 g, 30 mmol). In an ice bath at -80 °C, add n-butyllithium (18 mL, 45 mmol) and triisopropyl borate (8.56 g, 45 mmol) dropwise, stirring for 1 h. After the reaction is complete, add 45 mL of 1 mol / L dilute hydrochloric acid to the reaction mixture, stir, and separate the liquid to obtain the upper organic phase. Add saturated sodium chloride aqueous solution to the organic phase, stir, separate the liquid to obtain the upper organic phase, crystallize with petroleum ether, filter, and dry the solid to obtain 9.36 g of intermediate D-1, yield 79%. MALDI-TOF-MS mass spectrometry reading: 396.20 ([M+H)). + ), elemental analysis instrument test values: C, 78.90; H, 6.65; N, 3.59.

[0029] The synthesis steps for intermediates D-2 to D-6 are the same as those for intermediate D-1, except for the reactants. The specific reactants used are shown in Table 1 below. Table 1 Example 1: Synthesis of Compound 4 In a round-bottom flask, a mixed solution of 100 mL toluene, 50 mL ethanol, and 50 mL water was added. Intermediate D-3 (7.90 g, 20 mmol), 1-(5-chloro-[1,1'-biphenyl]-3-yl)naphthalene (6.93 g, 22 mmol), potassium carbonate (5.53 g, 40 mmol), and 0.01 g Pd132 (dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium) were added to the solution. Under nitrogen protection, the mixture was heated to 80 °C and reacted for 12 h. After the reaction was complete, the mixture was cooled to room temperature, 90 mL of water was added, and the mixture was filtered. The filter cake was washed with water, and the filtrate was separated and the organic phase was collected and concentrated. The filtrate was combined with the filter cake, and tetrahydrofuran was added and heated to dissolve the organic phase. Anhydrous magnesium sulfate was added for drying, followed by hot filtration, cooling to crystallize, and drying to obtain 8.18 g of compound 4, with a yield of 65%. The MALDI-TOF-MS mass spectrometry value was 630.31 ([M+H)). + ).

[0030] The following target compounds were synthesized by repeating the synthesis process of compound 4; the reaction conditions were the same, except that the intermediates and starting materials listed in Table 2 below were used: Table 2 Example 15: Synthesis of Compound 59 In a round-bottom flask, 200 mL of toluene, intermediate b-6 (7.72 g, 20 mmol), 3,9'-bicarbazole (7.31 g, 22 mmol), sodium tert-butoxide (3.84 g, 40 mmol), and tris(dibenzylacetone)dipalladium (0.2 g, 0.2 mmol) were added. Under nitrogen protection, the mixture was heated to 115 °C and reacted for 16 h. After the reaction was completed, the mixture was cooled to room temperature, and 200 mL of toluene and 200 mL of water were added to the reaction solution. The mixture was allowed to stand and separate, the organic phase was concentrated, tetrahydrofuran was added and heated to dissolve, then cooled to crystallize, filtered, and dried to obtain 9.20 g of compound 59, yielding 9.40 g of compound 59, with a yield of 69%. The MALDI-TOF-MS mass spectrometry value was 682.32 ([M+H)). + ).

[0031] The following target compounds were synthesized by repeating the synthesis process of compound 59; the reaction conditions were the same, except that the intermediates and starting materials listed in Table 3 below were used: Table 3 Performance testing: The glass substrate with a 120nm ITO transparent film was ultrasonically cleaned with acetone, isopropanol and deionized water for 10 minutes each, vacuum dried at 105°C for 2 hours, and then UV ozone washed for 15 minutes. The ITO glass substrate was then transferred to a vacuum evaporation machine. On the side where the ITO thin film is formed, molybdenum trioxide (MoO3) is vacuum evaporated to form a 10 nm thick hole injection layer. On the hole injection layer described above, 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC) is vacuum evaporated to form a hole transport layer with a thickness of 70 nm. On the hole transport layer mentioned above, the compounds in Table 4 (as the light-emitting host material, 90 wt%) and the dopants in Table 4 (as the light-emitting guest material, 10 wt%) are jointly vacuum evaporated to form a light-emitting layer with a thickness of 30 nm. On the aforementioned light-emitting layer, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) is vacuum-deposited to form a 5 nm hole-blocking layer. On the aforementioned light-emitting layer, 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]dipyridine (TmPyPB) is vacuum-deposited to form an electron transport layer with a thickness of 40 nm; On the aforementioned electron transport layer, lithium fluoride (LiF) is vacuum-deposited to form an electron injection layer with a thickness of 1 nm. Finally, aluminum (Al) is vacuum-deposited onto the aforementioned electron-injection layer to form a 100 nm cathode.

[0032] The luminescence characteristics of the prepared organic electroluminescent device were tested, and the test results are shown in Table 4. Table 4 In Table 4 above, Ir(ppy)3 is tris(2-phenylpyridine)iridium, BCzVBi is 4,4'-(bis(9-ethyl-3-carbazolevinyl)-1,1'-biphenyl), and Comparative Compound 1 and Comparative Compound 2 have the following structures: As can be seen from the table above, the organic compounds of this invention possess high glass transition temperatures (Tg), good thermal stability, and purer light colors. When the compounds provided by this invention are used as the light-emitting layer of organic electroluminescent devices, the driving voltage of the organic electroluminescent devices can be effectively reduced, the luminous efficiency of the devices can be improved, and the lifespan of the devices can be extended.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A carbazole fused-ring compound, characterized in that: The compound has the structural formula shown in Formula 1: Any two adjacent bonds among X1, X2, X3, and X4 form The remainder are CH; L is selected from direct linkages, phenylene, or fused and aryl groups with 10-15 carbon atoms; A is selected from aryl groups with 6-30 carbon atoms (substituted or unsubstituted), arylamine groups with 6-30 carbon atoms (substituted or unsubstituted), or heteroaryl groups with 6-30 carbon atoms (substituted or unsubstituted).

2. The carbazole fused-ring compound according to claim 1, characterized in that, The compound has the structural formulas shown in Formulas 1-1 to 1-3: 。 3. The carbazole fused-ring compound according to claim 1, characterized in that, Fused aryl groups with 10-15 carbon atoms are aryl groups containing 2-3 phenyl groups; Aryl groups with 6-30 carbon atoms are aromatic groups containing 2-4 phenyl groups, which are connected by single bonds, fused bonds, or a combination of both. The aromatic amino group with 6-30 carbon atoms is -NR1R2, where R1 and R2 are aromatic or heteroaromatic groups containing 2-4 phenyl groups, and the linkage between the phenyl groups is selected from any one or more combinations of single bond linkage, fused linkage, or heteroatom linkage. Heteroaryl groups with 6-30 carbon atoms are heteroaryl groups containing 1-2 heteroatoms and 2-4 phenyl groups; The substituents in aryl groups with 6-30 substituted carbon atoms, arylamine groups with 6-30 substituted carbon atoms, and heteroaryl groups with 6-30 substituted carbon atoms are alkyl, cyano, or phenyl groups with 1-4 carbon atoms. The heteroatoms are O, S, and N.

4. The carbazole fused-ring compound according to claim 1, characterized in that, A is selected from 、 、 、 ； In formula A-1, R3-R7 are independently represented as H, cyano, hydroxyl, mercapto, or C, respectively. 1-4 Alkyl groups, or those composed of cyano groups, C 1-4 Alkyl, phenyl-substituted or unsubstituted C 6-12 aryl, R 3-7 Any two adjacent groups in the group are not related or bonded to form a fused aromatic ring or a heteroaromatic ring; In formula A-2, n is selected from 0, 1, or 2, and each R8 is independently represented as a cyano group, C group, etc. 1-4 Alkyl groups, or those composed of cyano groups, C 1-4 Alkyl, phenyl-substituted or unsubstituted C 6-12 The aryl group, or the group consisting of cyano, C 1-4 Alkyl, phenyl-substituted or unsubstituted C 6-18 heteroaryl groups, R9 is represented by H, C 1-4 alkyl, C 6-12 The aryl group, or R9 is the linking site with L; R 10 -R 13 Each can be represented independently as the structure shown in A-1 or A-2; Z1-Z3 are each independently represented as N or CH, and at least one of them is N.

5. The carbazole fused-ring compound according to claim 4, characterized in that: C 6-12 The aryl group is selected from: phenyl, biphenyl, naphthyl; C 6-12 The heteroaryl group is selected from: carbazolyl, dibenzofuranyl, and dibenzothiophenel.

6. The carbazole fused-ring compound according to claim 4, characterized in that, It has cyano group, C 1-4 The following structural formulas are used for alkyl, phenyl-substituted or unsubstituted compounds: , , ; It has cyano group, C 1-4 The following structural formulas are used for alkyl, phenyl-substituted or unsubstituted compounds: , , , ; Z4 is selected from C(CH3)2, O, and S; Z5 is selected from C(CH3)2, O, S, and N-Ph.

7. The carbazole fused-ring compound according to claim 1, characterized in that, The fused and aryl groups with 10-15 carbon atoms are selected from any of the following structural formulas: , .

8. The carbazole fused-ring compound according to claim 7, characterized in that, The compound is any one of formulas 1 to 170: 。 9. An organic light-emitting device, comprising a cathode, an anode, and an organic material layer disposed between the cathode and the anode, characterized in that, The organic material layer comprises the carbazole fused-ring compound as described in any one of claims 1-8.

10. The organic light-emitting device according to claim 9, characterized in that, The organic layer includes any one, two or more of the following: a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, an electron blocking layer, a hole blocking layer, a light-emitting layer, and a light-emitting auxiliary layer. The organic layer containing an organic fused-ring compound is the light-emitting layer.

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