Indole (3, 2, 1-JK) carbazole derivative and organic electroluminescent device thereof

Abstract

The invention discloses an indole (3, 2, 1-JK) carbazole derivative and an organic light-emitting device thereof, and belongs to the technical field of organic light-emitting materials and semiconductors, the indole (3, 2, 1-JK) carbazole derivative takes indole (3, 2, 1-JK) carbazole as a donor group and an aromatic fused ring as a pi bridge connected donor-acceptor group, and a spatial TADF with donor units and acceptor units facing each other is designed. The compound combines the characteristics of indole and carbazole, and shows excellent hole transport performance, high HOMO energy level and good thermal stability. In addition, the compound as a luminescent layer material has the advantages of low starting voltage, high luminous efficiency, high brightness and the like, and is suitable for preparation of high-color-purity OLED devices. The compound has good thermal stability and film-forming property, so that the compound has good application prospects in rigid and flexible OLED devices, and has the advantages of saving cost, improving processing precision and the like. The material has wide development potential in the future display technology.

Description

Technical Field

[0001] This invention belongs to the field of organic light-emitting materials and semiconductor technology, and relates to an indole (3,2,1-JK) carbazole derivative and its organic electroluminescent device. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are considered a core development direction for next-generation solid-state lighting and full-color display technologies due to their self-emissive properties, high contrast, wide viewing angle, and flexibility. Their light-emitting mechanism is primarily based on electroluminescence: under an applied electric field, electrons injected from the cathode and holes injected from the anode recombine in the organic functional layer to form excitons. These excitons transfer energy to the luminescent material molecules, causing them to transition from the ground state to an excited state. When the excited-state molecules return to the ground state through radiative transitions, they release photons, thus emitting light.

[0003] Although the performance (such as efficiency and lifetime) of OLED devices has been significantly improved through optimization of luminescent material systems, further improvement of luminescent efficiency remains a core challenge in current research. Traditional fluorescent materials can only utilize 25% of singlet excitons, while phosphorescent materials, although achieving 100% internal quantum efficiency through triplet excitons, rely on noble metal (such as iridium and platinum) complexes, resulting in high costs and insufficient stability of blue light materials. In recent years, thermally activated delayed fluorescence (TADF) materials have become a research hotspot due to their theoretically 100% exciton utilization rate and lack of noble metal requirements. However, traditional TADF materials still suffer from the following problems: 1. Efficiency roll-off: efficiency drops sharply at high current densities due to exciton annihilation; 2. Insufficient color purity: strong charge transfer characteristics of donor-acceptor (DA) lead to broadening of the emission spectrum; 3. Molecular stacking defects: π-π stacking induces concentration quenching, reducing the luminescent efficiency of the thin film.

[0004] To overcome the aforementioned limitations, sterically hindered thermally activated delayed fluorescence (TADF) materials, by introducing sterically hindered groups to regulate molecular stacking behavior, possess the following significant advantages: First, they effectively suppress exciton quenching; the steric hindrance effect reduces the degree of intermolecular aggregation, thereby weakening nonradiative transition processes. Second, they achieve precise energy level control; through the spatial separation strategy of donor (D)-acceptor (A) units, a smaller singlet-triplet energy level difference can be constructed, corresponding to Δ... E ST <0.05 eV; Thirdly, it significantly improves color purity, and the rigid molecular framework can effectively suppress spectral broadening, specifically, the full width at half maximum (FWHM) is <50 nm. However, the steric hindrance TADF materials currently reported still have key problems such as complex synthesis routes, imbalanced carrier transport performance, and short lifespan of blue light devices. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an indole (3,2,1-JK) carbazole derivative and its organic electroluminescent device to solve the key problems of imbalance in carrier transport performance and short lifespan of blue light devices in the prior art TADF materials, thereby improving the luminous efficiency and lifespan of electroluminescent devices.

[0006] To achieve the above objectives, the present invention employs the following technical solution: An indole (3,2,1-JK)carbazole derivative, the structural formula of which is shown in general formula 1:

[0007] in," "A carbon chain containing 2-3 carbon atoms," Connected to Ar2 respectively in " The two ends of “”; Ar1 ​​is selected from substituted or unsubstituted C6~C 30 Aryl group; Ar2 is selected from C6~C 30 The substituted or unsubstituted heteroaryl group; R1 and R2 are independently selected from H, D, or straight-chain alkyl, alkoxy, having 1 to 10 C atoms, or branched or cyclic alkyl, alkoxy, or silyl groups having 3 to 10 C atoms.

[0008] A further improvement of the present invention is that: Preferably, Ar1 is derived from one of the following groups Y1 to Y6:

[0009] in," "Indicates Ar1 and the main structure" The * indicates a bonding site with Ar2. Y2, Y3, Y5, and Y6 are each bonded to Ar1 via a bonding site; among them, R3 and R4 are independently hydrogen, substituted or unsubstituted C1~C. 10 alkyl.

[0010] Preferably, R1 and R2 are each independently selected from hydrogen, methyl or tert-butyl.

[0011] Preferably, Ar2 is one of the following groups G1 to G15:

[0012] Where * represents the bonding site between Ar2 and Ar1, and R5 and R6 are independently selected from hydrogen, cyano, and trifluoromethyl, respectively.

[0013] Preferably, the indole (3,2,1-JK)carbazole derivative is selected from one of the following compounds 1 to 211:

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

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[0024]

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[0038] .

[0039] A second aspect of the present invention discloses an organic electroluminescent device, comprising a cathode, an anode, and an organic layer located between the cathode and the anode. The organic layer comprises a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, and the hole blocking layer, electron transport layer, and electron injection layer stacked sequentially. The light-emitting layer comprises a host light-emitting material and a guest light-emitting material. The host light-emitting material comprises a first light-emitting host and a second light-emitting host. The second light-emitting host material is an indole (3,2,1-JK) carbazole derivative as described in any one of claims 1-5.

[0040] Preferably, in the light-emitting layer, the mass ratio of the first light-emitting subject, the second light-emitting subject, and the guest light-emitting material is (30~70):(30~70):(0.5~5).

[0041] Preferably, in the light-emitting layer, the first light-emitting host material is... ; The guest luminescent material is preferably... .

[0042] Preferred, The hole injection layer is ; The hole transport layer is HT-1 or HT-2, and its structural formula is as follows: ; The electron blocking layer is EB-1 or EB-2, and its structural formula is: ; The hole-blocking layer is HB-1 or HB-2, and its structural formula is: ; The electron transport layer is ET-1 or ET-2, and its structural formula is as follows: ; The electron injection layer is made of LiF.

[0043] Preferably, in the light-emitting layer, the anode is one or more combinations of indium tin oxide, indium zinc oxide, tin dioxide, and zinc oxide; and the cathode is magnesium, silver, aluminum, aluminum-lithium alloy, calcium, magnesium-indium alloy, or magnesium-aluminum alloy.

[0044] Compared with the prior art, the present invention has the following beneficial effects: This invention provides an indole (3,2,1-JK)carbazole derivative and its organic electroluminescent device. This indole (3,2,1-JK)carbazole derivative can be used as the host luminescent material to fabricate electroluminescent devices. This indole (3,2,1-JK)carbazole derivative is a spatial TADF material. While ensuring an efficient RISC process, the molecular design is optimized to balance luminous efficiency, color purity, and device stability, thereby promoting the application of OLED technology in high-end display fields. The indole (3,2,1-JK)carbazole derivative of this invention has the following advantages: (1) This invention uses indole(3,2,1-JK)carbazole as the donor group and an aromatic fused ring as a π-bridge to connect the donor and acceptor groups, designing a face-to-face spatial TADF that avoids the electronic coupling generated by chemical bonds in traditional TADF molecules, thereby achieving extremely small Δ E ST(Singlet-triplet energy level difference) to achieve higher efficiency and performance stability under high brightness.

[0045] (2) The molecular configuration of the present invention can effectively prevent the close packing of luminescent molecules, thereby reducing fluorescence quenching caused by molecular aggregation. In addition, the steric hindrance of the donor and acceptor groups and the substituents on the aromatic ring bridge can effectively limit the vibration and rotation within the molecule, reduce non-radiative transition pathways, improve radiative transition efficiency, and enhance luminescence efficiency.

[0046] (3) The spatial TADF of the present invention can adjust the degree of conjugation of molecules and the range of electron delocalization by modifying the donor or acceptor units relatively independently, which helps to achieve narrow-band emission and thus improve the color purity of the emission.

[0047] (4) The raw materials of the indole (3,2,1-JK) carbazole derivatives of the present invention are simple and readily available, the preparation method is simple, the reaction route is short, the post-processing is simple, the yield is high, and it is easy to realize the large-scale production of indole (3,2,1-JK) carbazole derivatives.

[0048] (5) The electroluminescent device provided by the present invention uses an indole (3,2,1-JK) carbazole derivative as the main light-emitting material, which effectively improves the luminous efficiency of the device, extends its service life, and emits light with good color purity. Furthermore, the emission wavelength of the electroluminescent device is in the blue light range. Attached Figure Description

[0049] Figure 1 This is a cross-sectional view of an electroluminescent device according to the present invention; Explanation of reference numerals in the attached figures: 1. Substrate; 2. Anode; 3. Hole injection layer; 4. Hole transport layer; 5. Electron blocking layer; 6. Light emitting layer; 7. Hole blocking layer; 8. Electron transport layer; 9. Electron injection layer; 10. Cathode; and 10. Covering layer.

[0050] Figure 2 The 1H NMR spectrum data for compound 41; Figure 3 The data are the 1H NMR spectra of compound 93. Detailed Implementation

[0051] The present invention will now be described in further detail with reference to the accompanying drawings: To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0052] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0053] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0054] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0055] The first aspect of this invention discloses an indole (3,2,1-JK)carbazole derivative, the general structural formula of which is shown in Formula 1:

[0056] in," "A carbon chain containing 2-3 carbon atoms," Connected to Ar2 respectively in " The two ends of “”; Ar1 ​​is selected from substituted or unsubstituted C6~C 30 Aryl group; Ar2 is selected from C6~C 30 The substituted or unsubstituted heteroaryl group; R1 and R2 are independently selected from H, D, or straight-chain alkyl, alkoxy, having 1 to 10 C atoms, or branched or cyclic alkyl, alkoxy, or silyl groups having 3 to 10 C atoms.

[0057] In some embodiments of the present invention, Ar1 is selected from one of the following groups Y1 to Y6:

[0058] Among them, the groups Y1~Y6 are " "Indicates Ar1 and the main structure" The bonding sites are indicated by "*" in groups Y1~Y6, which represent potential bonding sites with Ar2. Groups Y2, Y3, Y5, and Y6 are each bonded to Ar1 via one bonding site. R3 and R4 are each independently hydrogen, substituted, or unsubstituted C1~C1 groups. 10 alkyl.

[0059] Preferably, R1 and R2 are each independently selected from hydrogen, methyl, or tert-butyl.

[0060] In some embodiments of the present invention, Ar2 is preferably selected from one of the following groups G1 to G15:

[0061] In this context, the "*" in groups G1~G15 represents the bonding site between Ar2 and Ar1, and R5 and R6 are independently selected from hydrogen, cyano, and trifluoromethyl, respectively.

[0062] In some embodiments of the present invention, the indole (3,2,1-JK)carbazole derivative is selected from one of the following compounds 1 to 211:

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[0088] In this invention, the term "aryl" refers to an all-carbon monocyclic or fused polycyclic (i.e., a ring sharing adjacent carbon atom pairs) group having a conjugated π-electron system.

[0089] In this invention, the term "heteroaryl" refers to the general term for groups obtained by replacing one or more aromatic carbon atoms or non-aromatic carbon atoms in an aryl group with heteroatoms. The heteroatoms include, but are not limited to, oxygen, sulfur, nitrogen, silicon, germanium, selenium, boron, arsenic or phosphorus atoms. The heteroaryl group can be a monocyclic heteroaryl, a polycyclic heteroaryl or a fused-ring heteroaryl.

[0090] The present invention also provides an electroluminescent device, comprising a cathode, an anode, and an organic layer located between the cathode and the anode. The organic layer comprises a hole injection layer, a hole transport layer, an electron blocking layer, and a light-emitting layer stacked sequentially. The light-emitting layer comprises a host light-emitting material and a guest light-emitting material. The host light-emitting material comprises a first light-emitting host and a second light-emitting host. The second light-emitting host material comprises an indole (3,2,1-JK) carbazole derivative as shown in formula (1). The mass ratio of the first light-emitting host, the second light-emitting host, and the guest light-emitting material is (30~70):(30~70):(0.5~5), preferably 60:40:5, wherein the sum of the masses of the first light-emitting host and the second light-emitting host is 100%.

[0091] Preferably, the first light-emitting host material in this invention is preferably... .

[0092] Preferably, the guest luminescent material in this invention is preferably... .

[0093] Preferably, the material of the hole injection layer in this invention is preferably... .

[0094] Preferably, the hole transport layer in this invention is selected from one of the following materials: .

[0095] Preferably, the material of the electron blocking layer in this invention is selected from one of the following materials: .

[0096] Preferably, the material of the hole-blocking layer in this invention is selected from one of the following materials: .

[0097] Preferably, the electron transport layer in this invention is selected from one of the following materials: .

[0098] In this invention, the material of the electron injection layer is LiF.

[0099] Preferably, the substrate is disposed outside the anode or cathode, and its material is selected from glass or polymer materials with high mechanical strength, excellent thermal stability, and waterproof and light-transmitting properties. Further, when applied to a display device, the substrate can integrate a thin-film transistor (TFT) array, and a preset display pattern can be formed by driving the TFT array. The thickness and surface treatment process of the substrate can be adjusted according to the device requirements, for example, using chemically strengthened glass or a polyimide flexible substrate.

[0100] The anode can be formed by sputtering or depositing a functional layer material on the substrate. The functional layer material is selected from oxide transparent conductive materials, including but not limited to one or more combinations of indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), and zinc oxide (ZnO).

[0101] The cathode can be made of a highly conductive elemental metal or alloy, preferably magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium alloy (Al-Li), calcium (Ca), magnesium-indium alloy (Mg-In), or magnesium-aluminum alloy (Mg-Al). The thickness of the anode can be 10~200 nm, and the thickness of the cathode can be 50~300 nm, which can be adjusted according to the photoelectric performance requirements of the device.

[0102] Preferably, the organic layer is formed on the hole transport layer by vacuum thermal evaporation, solution processing, or printing. The solution processing includes, but is not limited to, spin coating, dip coating, or inkjet printing; the printing process includes, but is not limited to, gravure printing, screen printing, or inkjet printing.

[0103] The electroluminescent device described in this invention can be applied to light-emitting devices, flat panel display devices, or photoelectric signal conversion devices in optical communication systems.

[0104] The synthesis process of the indole (3,2,1-JK) carbazole derivatives described in this invention is as follows.

[0105] The raw materials required for the synthesis process are as follows:

[0106]

[0107]

[0108]

[0109]

[0110] The intermediate is synthesized as follows: The steps for synthesizing A1 are as follows:

[0111]

[0112] Synthesis of A1-1: Procedure: A mixture of a1 (45.1 g, 0.2 mol) and NaH (4.8 g, 0.2 mol) was dissolved in dimethylformamide and stirred under an inert atmosphere until gas release was complete. Then, 5-chloro-1,3-dibromo-2-fluorobenzene (57.2 g, 0.2 mol) was added, and the mixture was continuously stirred and heated at 150 °C. The reaction progress was monitored by thin-layer chromatography (TLC). After the reaction was complete, the solvent was evaporated under reduced pressure, the residue was treated with 0.1 M HCl water, and then extracted with dichloromethane. Purification by column chromatography yielded 77.6 g of A1-1 (80% yield), HPLC purity 99%, and LC-MS showed an M+1 molecular weight of 493.96.

[0113] Synthesis of A1-2: Procedure: Under nitrogen protection, compound A1-1 (98.8 g, 0.2 mol), potassium carbonate (82.9 g, 0.6 mol), and (NHC)Pd(allyl)Cl catalyst (10% mol) were added to the reaction flask. After three purging cycles, anhydrous DMA (1.0 L) was injected. The reaction system was stirred at 95 °C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, quenched with water, and extracted with ethyl acetate. The organic phases were combined, washed successively with saturated ammonium chloride solution and saturated brine, and dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated under reduced pressure to obtain the crude product. Finally, the crude product was purified by silica gel column chromatography (petroleum ether / ethyl acetate gradient elution) to obtain 55.0 g of the target product A1-2, with a yield of 83%, HPLC purity of 99%, and LC-MS showing an M+ molecular weight of 331.11.

[0114] Synthesis of A1: Procedure: Under an inert atmosphere, add Al-2 (66.2 g, 0.2 mol), pinacol diboronate (53 g, 0.21 mol), potassium acetate (39 g, 0.4 mol), and 2 L of 1,4-dioxane to a 5 L three-necked flask. After stirring, heat to 60-65 °C, then add X-Phos (4.8 g, 0.01 mol) and Pd2(dba)3 (3.7 g, 0.004 mol). Continue heating to reflux for 8 hours until the reaction is complete. Filter the reaction solution directly, collect the filtrate, concentrate to dryness under reduced pressure, dissolve in 1 L of toluene, and wash with water. After passing the organic phase through a silica gel column, concentrate the column chromatography solution again under reduced pressure until solid precipitates, then stop. Cool to 10-15 °C for crystallization. After crystallization, filter and dry to obtain 67.7 g of Al, yield 80%, HPLC purity 99%, LC-MS shows M+ molecular weight 423.24.

[0115] The steps for synthesizing A2 are as follows:

[0116]

[0117] Synthesis of A2-1: Procedure: A mixture of 4,4'-dimethoxydiphenylamine (a2) (45.9 g, 0.2 mol) and NaH (4.8 g, 0.2 mol) was dissolved in dimethylformamide and stirred under an inert atmosphere until gas release was complete. Then, 5-chloro-1,3-dibromo-2-fluorobenzene (57.2 g, 0.2 mol) was added, and the mixture was continuously stirred and heated at 150 °C. The reaction progress was monitored by thin-layer chromatography (TLC). After the reaction was complete, the solvent was evaporated under reduced pressure, the residue was treated with 0.1 M HCl water, and then extracted with dichloromethane. Purification by column chromatography yielded 79.2 g of A2-1, with a yield of 80%, HPLC purity of 99%, and LC-MS showing a molecular weight of M of 496.92.

[0118] Synthesis of A2-2: Procedure: Under nitrogen protection, compound A2-1 (99.5 g, 0.2 mol), potassium carbonate (82.9 g, 0.6 mol), and (NHC)Pd(allyl)Cl catalyst (10% mol) were added to the reaction flask. After three purging cycles, anhydrous DMA (1.0 L) was injected. The reaction system was stirred at 95 °C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, quenched with water, and extracted with ethyl acetate. The organic phases were combined, washed successively with saturated ammonium chloride solution and saturated brine, and dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated under reduced pressure to obtain the crude product. Finally, the crude product was purified by silica gel column chromatography (petroleum ether / ethyl acetate gradient elution) to obtain 55.7 g of the target product A2-2, with a yield of 83%, HPLC purity of 99%, and LC-MS showing an M+1 molecular weight of 335.79.

[0119] Synthesis of A2: Procedure: Under an inert atmosphere, add A2-2 (67.2 g, 0.2 mol), pinacol diboronate (53 g, 0.21 mol), potassium acetate (39 g, 0.4 mol), and 2 L of 1,4-dioxane to a 5 L three-necked flask. After stirring, heat to 60-65 °C, then add X-Phos (4.8 g, 0.01 mol) and Pd2(dba)3 (3.7 g, 0.004 mol). Continue heating to reflux for 8 hours until the reaction is complete. Filter the reaction solution directly, collect the filtrate, concentrate under reduced pressure to dryness, dissolve in 1 L of toluene, and wash with water. After passing the organic phase through a silica gel column, concentrate the column chromatography solution again under reduced pressure until solid precipitates, then stop. Cool to 10-15 °C for crystallization. After crystallization, filter and dry to obtain 68 g of A2, yield 80%, HPLC purity 99%, LC-MS shows M+ molecular weight 427.31.

[0120] The synthesis steps for A3 are as follows:

[0121] Synthesis of A3-1: Procedure: A mixture of 4,4'-di-tert-butyldiphenylamine (a4) (56.3 g, 0.2 mol) and NaH (4.8 g, 0.2 mol) was dissolved in dimethylformamide and stirred under an inert atmosphere until gas release was complete. Then, 5-chloro-1,3-dibromo-2-fluorobenzene (57.2 g, 0.2 mol) was added, and the mixture was continuously stirred and heated at 150 °C. The reaction progress was monitored by thin-layer chromatography (TLC). After the reaction was complete, the solvent was evaporated under reduced pressure, the residue was treated with 0.1 M HCl water, and then extracted with dichloromethane. Purification by column chromatography yielded 90.8 g of A3-1, with a yield of 83%, HPLC purity of 99%, and LC-MS showing a molecular weight of M of 549.03.

[0122] Synthesis of A3-2: Procedure: Under nitrogen protection, compound A3-1 (55.0 g, 0.1 mol), potassium carbonate (41.5 g, 0.3 mol), and (NHC)Pd(allyl)Cl catalyst (5% mol) were added to the reaction flask. After three purging cycles, anhydrous DMA (1.0 L) was injected. The reaction system was stirred at 95 °C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, quenched with water, and extracted with ethyl acetate. The organic phases were combined, washed successively with saturated ammonium chloride solution and saturated brine, and dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated under reduced pressure to obtain the crude product. Finally, the crude product was purified by silica gel column chromatography (petroleum ether / ethyl acetate gradient elution) to obtain 32.2 g of the target product A3-2, with a yield of 85%, HPLC purity of 99%, and LC-MS showing an M+ molecular weight of 387.95.

[0123] Synthesis of A3: Procedure: Under an inert atmosphere, add A3-2 (77.6 g, 0.2 mol), pinacol diboronate (53 g, 0.21 mol), potassium acetate (39 g, 0.4 mol), and 2 L of 1,4-dioxane to a 5 L three-necked flask. After stirring, heat to 60-65 °C, then add X-Phos (4.8 g, 0.01 mol) and Pd2(dba)3 (3.7 g, 0.004 mol). Continue heating to reflux for 8 hours until the reaction is complete. Filter the reaction solution directly, collect the filtrate, concentrate to dryness under reduced pressure, dissolve in 1 L of toluene, and wash with water. After passing the organic phase through a silica gel column, concentrate the column chromatography solution again under reduced pressure until solid precipitates, then stop. Cool to 10-15 °C for crystallization. After crystallization, filter and dry to obtain 84.4 g of A3, yield 88%, HPLC purity 99%, LC-MS shows M+ molecular weight 479.47.

[0124] The steps for synthesizing B1 are as follows:

[0125] Procedure: Under an inert atmosphere, 1-bromo-3,5-di-tert-butyl-2-iodobenzene (73.0 g, 0.2 mol), Al (84.6 g, 0.2 mol), 2 L of tetrahydrofuran, potassium phosphate (42 g, 0.2 mol), 1 L of deionized water, and Pd(PPh3)4 (120 mg, 0.1 mmol) were added to a 5 L three-necked flask. The system was heated to reflux and the reaction was continued for 18 h until completion. The reaction solution was washed with water and separated. The organic phase was passed through a diatomaceous earth funnel, and the filtrate was collected. The filtrate was concentrated and dried under reduced pressure to obtain a crude solid. 30 mL of an appropriate proportion of ethyl acetate / petroleum ether solution was added, and the mixture was dispersed and slurried. Filtration yielded 93.5 g of intermediate B1, with a yield of 83%, HPLC purity of 99%, and LC-MS showing an M+1 molecular weight of 564.22.

[0126] Following the procedure in B1, replacing raw material b1 with b2~b8 respectively, and replacing intermediate A1 with A2 and A3 respectively, will yield the remaining intermediates B2~B24:

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[0128]

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[0131]

[0132] The following description, in conjunction with specific embodiments, provides further details.

[0133] Synthesis example 1 The synthetic steps of compound 41 are as follows:

[0134] Procedure: Under an inert atmosphere, 2,4-diphenyl-6-(4-(4,4,5,5-tetramethyl-1,3,2-dioxoborhexacyclopentan-2-yl)phenyl)-1,3,5-triazine (4.35 g, 0.01 mol), B1 (5.63 g, 0.01 mol), 1,4-dioxane (50 mL), potassium phosphate (4.2 g, 0.02 mol), deionized water (10 mL), and Pd(PPh3)4 (120 mg, 0.1 mmol) were added to a three-necked flask. The system was heated to reflux and the reaction was continued for 18 h until the reaction was complete. The reaction solution was first washed with water and separated. The organic phase was passed through a diatomaceous earth funnel and the filtrate was collected. The solution was concentrated under reduced pressure to obtain a crude solid product. 30 mL of an appropriate proportion of ethyl acetate / petroleum ether solution was added, and the mixture was dispersed and slurried. After filtration, 6.74 g of compound 41 was obtained, with a yield of 85%. The HPLC purity was 99%, and the LC-MS showed an M+1 molecular weight of 793.42.

[0135] See Figure 2 The 1H NMR data of compound 41 are as follows: 1H NMR (500 MHz, Chloroform-d) δ 8.33–8.30 (m, 4H), 8.26 (d, J = 1.1 Hz, 1H), 8.15 (s, 2H), 8.08 – 8.04 (m, 3H), 7.75 (dd, J = 6.3, 1.7 Hz, 1H), 7.51 – 7.46 (m, 9H), 7.42 – 7.40 (m, 2H), 7.38 (t, J = 1.1 Hz, 1H), 7.33 – 7.28 (m, 2H), 1.43 – 1.33 (m, 27H).

[0136] Synthesis example 2 Synthesis of compound 93:

[0137] Procedure: Under an inert atmosphere, B10 (5.05 g, 0.01 mol), 1,8-naphthalenediamine (1.97 g, 0.01 mol), and 50 mL of toluene were added to a 100 mL three-necked flask. The mixture was stirred until the solution was clear. Pd2(dba)3 (183 mg, 0.2 mmol), Am-phos (133 mg, 0.5 mmol), and sodium tert-butoxide (1.9 g, 0.01 mol) were added. The reaction mixture was heated to 120 °C and reacted for 10 h. After the reaction was completed, the mixture was filtered while hot using diatomaceous earth. The filtrate was cooled to room temperature, washed with purified water, and separated. The organic phase was retained, and the aqueous phase was extracted with ethyl acetate. The organic phases were combined, dried over anhydrous magnesium sulfate, concentrated, and column chromatography to obtain compound 93, weighing 5.16 g, with a yield of 83% and an HPLC purity of 99%. LC-MS showed an M+ molecular weight of 622.19.

[0138] See Figure 3 The 1H NMR data for compound 93 are as follows: 1H NMR (500 MHz, Chloroform-d) δ 8.45 (dd, J = 8.2, 1.1 Hz, 2H), 8.36 (dd, J = 7.6, 1.3 Hz, 2H), 8.10 (s, 2H), 8.02 (d, J = 8.3 Hz, 1H), 7.83 – 7.76 (m, 4H), 7.73 – 7.70 (m, 1H), 7.62 – 7.58 (m, 2H), 7.61 – 7.53 (m, 2H), 7.55 – 7.48 (m, 2H), 7.02 (dd, J = 8.1, 2.2 Hz, 2H), 3.82 (s, 6H). The synthesis processes of the compounds described in this invention are all carried out following the synthesis processes of compounds 41 and 93 mentioned above. The synthetic routes are similar, but the specific purification processes of the compounds require either crystallization purification based on the properties of the compounds themselves or separation and purification using chromatographic columns.

[0139] Device fabrication and testing applications were carried out using the above-mentioned preferred indole (3,2,1-JK) carbazole derivatives, and the above-mentioned preferred indole (3,2,1-JK) carbazole derivatives were used as the main light-emitting material by vapor deposition.

[0140] Based on the aforementioned preferred indole (3,2,1-JK)carbazole derivatives, the material was applied to the luminescent layer in the test device sample. The excellent device performance suggests that the material can be used in various applications such as light emission illumination, color imaging (e.g., mobile phone displays, automotive displays, tablet computers, televisions), and decorative crafts.

[0141] Schematic diagrams of the electroluminescent devices in the various embodiments and comparative examples of this invention are shown below. Figure 1 As shown, the device comprises a substrate 1, an anode layer 2, a hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, a light-emitting layer 6, a hole blocking layer 7, an electron transport layer 8, an electron injection layer 9, and a cathode layer 10. Finally, a cover layer material is deposited and the device is encapsulated to complete the fabrication process of the electroluminescent device.

[0142] Example 1 (Electroluminescent device containing compound 1) An electroluminescent device containing compound 1, comprising, in the direction from the anode layer to the cathode layer, a transparent polyimide (PI) film, an indium tin oxide (ITO) material, HI-1, HT-1, EB-1, a light-emitting layer, HB-1, ET-1, LiF, and Mg:Ag (1:9). In the luminescent layer, CBP and Compound 1 are used as the host luminescent materials, and GD-1 is used as the guest luminescent material, with a mass ratio of 60:40:5.

[0143] Specific fabrication process of the device embodiment: The device application methods and specific implementation processes of the materials are as follows: 1. The transparent substrate layer 1 is a transparent PI film. The ITO anode layer 2 (film thickness is 150nm) is washed by successively performing alkaline washing, pure water washing, drying, and then ultraviolet-ozone washing to remove organic residues on the transparent ITO surface.

[0144] 2. A layer of ITO material is adhered to a transparent PI film. Using a vacuum evaporation apparatus, a 10nm thick HI-1 layer is deposited as a hole injection layer 3. Next, a 60nm thick HT-1 layer is deposited as a hole transport layer 4. Following this, a 30nm thick EB-1 layer is deposited as an electron blocking layer 5. After the electron blocking materials are deposited, the emitting layer 6 of the OLED light-emitting device is fabricated. Its structure includes CBP as the first host material, compound 41 as the second host material, and GD-1 as the guest material. The mass ratio of CBP to compound 1 and GD-1 is 60:40:5, and the emitting layer thickness is 30nm. After the emitting layer 6, HB-1 is vacuum-deposited to a thickness of 5nm; this layer is the hole blocking layer 7. After the hole blocking layer 7, ET-1 is vacuum-deposited to a thickness of 30nm; this layer is the electron transport layer 8. On the electron transport layer 8, a 1nm thick LiF layer is fabricated using a vacuum evaporation apparatus; this layer is the electron injection layer 9. On the electron injection layer 9, a Mg:Ag electrode layer with a thickness of 80 nm is fabricated by a vacuum evaporation device, with a Mg:Ag mass ratio of 1:9. This layer is used as the cathode layer 10.

[0145] Examples 2-33 The difference from Example 1 is that in Examples 2 to 33, compounds 93, 10, 15, 22, 33, 36, 47, 56, 59, 64, 68, 69, 71, 78, 81, 90, 95, 98, 101, 108, 116, 120, 123, 128, 136, 138, 139, 143, 153, 165, 166, and 210 were selected as the second host luminescent material of the luminescent layer 6, respectively.

[0146] Comparative Example 1 The difference from Example 1 is that the light-emitting layer 6 uses the technology described in Chinese patent application publication number CN114249734A. As a secondary primary luminescent material.

[0147] The structure of the electroluminescent device is: transparent PI film / ITO (150nm) / HI-1 (10nm) / HT-1 (60nm) / EB-1 (30nm) / CBP:ref-88:GD-1=60:40:5 (30nm) / HB-1 (5nm) / ET-1 (30nm) / LiF (1nm) / Mg:Ag (Mg:Ag=1:9) (80nm).

[0148] Comparative Example 2 The difference from Example 1 is that the light-emitting layer 6 uses the technology described in Chinese patent application publication number CN114249734A. As a secondary primary luminescent material.

[0149] The structure of the electroluminescent device is: transparent PI film / ITO (150nm) / HI-1 (10nm) / HT-1 (60nm) / EB-1 (30nm) / CBP:ref-90:GD-1=60:40:5 (30nm) / HB-1 (5nm) / ET-1 (30nm) / LiF (1nm) / Mg:Ag (Mg:Ag=1:9) (80nm).

[0150] Comparative Example 3 The difference from Example 1 is that the light-emitting layer 6 uses the technology described in Chinese patent application publication number CN114249734A. As a secondary primary luminescent material.

[0151] The structure of the electroluminescent device is as follows: transparent PI film / ITO (150nm) / HI-1 (10nm) / HT-1 (60nm) / EB-1 (30nm) / CBP:ref-22:GD-1=60:40:5 (30nm) / HB-1 (5nm) / ET-1 (30nm) / LiF (1nm) / Mg:Ag (Mg:Ag=1:9) (80nm).

[0152] The electroluminescent devices from the above embodiments and comparative examples were fabricated into 30mm × 30mm samples. Then, under the same device fabrication process conditions, the anode and cathode layers were connected using an industry-known driving circuit. The luminous performance indicators of each electroluminescent device were tested. For the electroluminescent devices, at 10mA / cm... 2 The driving voltage and luminous efficiency were measured at a current density of 20 mA / cm². 2 The time required for the brightness to become 95% of its initial brightness at a given current density (LT) 95 (i.e., lifespan). The test results are shown in Table 1.

[0153] Table 1 Performance Test Table of Comparative Examples and Embodiments

[0154] Note: Here, EQE refers to 1000 cd / m 2 External quantum efficiency at operating brightness.

[0155] As can be seen from the performance data in Table 1, compared with the electroluminescent devices prepared by the second host luminescent materials ref-88, ref-90, and ref-22 in the comparative examples (comparative examples 1 to 3), the electroluminescent devices prepared by using the indole (3,2,1-JK) carbazole derivative of the present invention as the second host luminescent material have significantly improved overall luminous efficiency. Among them, the half-width at half-maximum is significantly narrowed, the external quantum efficiency is increased by about 65%, and the lifespan is extended by nearly 100%.

[0156] 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. An indole (3,2,1-JK) carbazole derivative, characterized in that, The structural formula of the indole (3,2,1-JK) carbazole derivative is shown in general formula 1: in," "A carbon chain containing 2-3 carbon atoms," Connected to Ar2 respectively in " The two ends of “”; Ar1 ​​is selected from substituted or unsubstituted C6~C 30 Aryl group; Ar2 is selected from C6~C 30 The substituted or unsubstituted heteroaryl group; R1 and R2 are independently selected from H, D, or straight-chain alkyl, alkoxy, having 1 to 10 C atoms, or branched or cyclic alkyl, alkoxy, or silyl groups having 3 to 10 C atoms.

2. The indole (3,2,1-JK) carbazole derivative according to claim 1, characterized in that, Ar1 is derived from one of the following groups Y1 to Y6: in," "Indicates Ar1 and the main structure" The * indicates a bonding site with Ar2. Y2, Y3, Y5, and Y6 are each bonded to Ar1 via a bonding site; among them, R3 and R4 are independently hydrogen, substituted or unsubstituted C1~C. 10 alkyl.

3. The indole (3,2,1-JK) carbazole derivative according to claim 1, characterized in that, R1 and R2 are each independently selected from hydrogen, methyl, or tert-butyl.

4. The indole (3,2,1-JK) carbazole derivative according to claim 1, characterized in that, Ar2 is one of the following groups G1 to G15: Where * represents the bonding site between Ar2 and Ar1, and R5 and R6 are independently selected from hydrogen, cyano, and trifluoromethyl, respectively.

5. An indole (3,2,1-JK) carbazole derivative according to claim 1, characterized in that, The indole (3,2,1-JK) carbazole derivatives are selected from one of the following compounds 1 to 211: 。 6. An organic electroluminescent device, characterized in that, The device includes a cathode, an anode, and an organic layer located between the cathode and the anode. The organic layer comprises a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, and the hole blocking layer, electron transport layer, and electron injection layer stacked sequentially. The light-emitting layer comprises a host light-emitting material and a guest light-emitting material. The host light-emitting material comprises a first light-emitting host and a second light-emitting host. The second light-emitting host material is an indole (3,2,1-JK) carbazole derivative as described in any one of claims 1-5.

7. An organic electroluminescent device according to claim 6, characterized in that, In the light-emitting layer, the mass ratio of the first light-emitting subject, the second light-emitting subject, and the guest light-emitting material is (30~70):(30~70):(0.5~5).

8. An organic electroluminescent device according to claim 6, characterized in that, In the light-emitting layer, the first light-emitting host material is ; The guest luminescent material is preferably... .

9. An organic electroluminescent device according to claim 6, characterized in that, The hole injection layer is ; The hole transport layer is HT-1 or HT-2, and its structural formula is as follows: ； The electron blocking layer is EB-1 or EB-2, and its structural formula is: ； The hole-blocking layer is HB-1 or HB-2, and its structural formula is: ； The electron transport layer is ET-1 or ET-2, and its structural formula is as follows: ； The electron injection layer is made of LiF.

10. An organic electroluminescent device according to claim 6, characterized in that, In the light-emitting layer, the anode is one or more combinations of indium tin oxide, indium zinc oxide, tin dioxide, and zinc oxide; the cathode is magnesium, silver, aluminum, aluminum-lithium alloy, calcium, magnesium-indium alloy, or magnesium-aluminum alloy.

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