Delayed fluorescence compound based on aryl and diazole unit as well as preparation method and application of delayed fluorescence compound

Abstract

The invention discloses a delayed fluorescence compound based on an aryl and diazole unit as well as a preparation method and application thereof, and belongs to the field of organic compound synthesis. According to the prepared delayed fluorescence compound based on the aryl and diazole unit, indolocarbazole and the aryl and diazole unit are connected together through a single bond, aryl or heteroaryl, and the compound has the advantages that the structure is simple; and a novel D-A-D system is constructed, which is beneficial to optimizing charge transfer characteristics and has important significance for improving the performance of photoelectric devices. When the delayed fluorescence compound prepared by the invention is used as a phosphorescent light-emitting main body of a light-emitting layer, an electron transport layer and a hole blocking layer and a delayed fluorescence material of the light-emitting layer, the layer has good charge carrier mobility and extremely long service life; the driving voltage and energy consumption of the organic EL device can be reduced, the efficiency of the organic EL device is increased, the half-life period of the organic EL device is prolonged, and the method has the economic advantage of industrial application.

Description

Technical Field

[0001] The invention belongs to the field of organic compound synthesis, and in particular relates to a delayed fluorescence compound based on an aryl oxadiazole unit and a preparation method and application thereof. Background Art

[0002] Organic electroluminescence is used in flat panel displays because of its high illumination, low weight, ultra-thin appearance, self-illumination without backlight, low energy consumption, wide viewing angle, high contrast, simple manufacturing and fast response time.

[0003] In general, an organic electroluminescence (hereinafter referred to as organic EL) device is composed of an organic material layer located between two electrodes, including a hole transport layer (HTL), an emitting layer (EML), and an electron transport layer (ETL). The basic mechanism of organic EL includes carrier injection, carrier transport, recombination, and the formation of luminescent excitons. When an external voltage is applied to the organic EL device, electrons and holes will be injected from the cathode and anode respectively, and electrons will be injected from the cathode into the lowest unoccupied molecular orbital (LUMO), and holes will be injected from the anode into the highest occupied molecular orbital (HOMO). When electrons and holes recombine in the luminescent layer, excitons will be formed and then emit light. When the luminescent molecule absorbs energy to reach an excited state, the excitons can be in a singlet state or a triplet state depending on the combination of electron and hole spins. The triplet excited state is reached by forming 75% of excitons by recombining electrons and holes. Decay from the triplet state is spin-forbidden, and therefore, fluorescent electroluminescent devices have an internal quantum efficiency of only 25%. In contrast to fluorescent electroluminescent devices, phosphorescent organic EL devices utilize spin-orbit interactions to promote cross-system crossing between singlet and triplet states, thereby obtaining singlet and triplet emission and an internal quantum efficiency of electroluminescent devices ranging from 25% to 100%. Spin-orbit interactions are accomplished by some heavy atoms, such as iridium, rhodium, platinum, and palladium, and phosphorescent transitions can be observed from excited metal-to-ligand charge-transfer transition (MLCT) states of organometallic complexes.

[0004] Recently, a thermally activated delayed fluorescence (TADF) mechanism has been developed and integrated into novel fluorescent organic EL devices, which converts spin-forbidden triplet excitons into singlet states through a reverse intersystem crossing (RISC) mechanism using materials with a small energy gap between singlet and triplet states to obtain highly efficient excitons. However, there is still a need to further improve the luminescence efficiency of organic EL devices at high current densities.

[0005] Organic EL utilizes triplet excitons and singlet excitons. Phosphorescent organic EL usually requires an additional hole blocking layer (HBL) between the light-emitting layer (EML) and the electron transport layer (ETL), or an additional electron blocking layer (EBL) between the light-emitting layer (EML) and the hole transport layer (HTL). Therefore, compared with singlet excitons, triplet excitons have a longer lifetime and a longer diffusion length. The purpose of using HBL or EBL is to limit the recombination of injected holes and electrons and to relax the excitons generated in the EML, thereby improving the efficiency of the device. In order to meet these effects, the hole blocking material or the electron blocking material must have HOMO and LUMO energy levels suitable for blocking holes or electrons from the EML to the ETL or to the HTL.

[0006] For full-color flat panel displays using active-matrix organic light-emitting diodes (AMOLED) or organic light-emitting diodes (OLED) as light-emitting panels, the use of phosphorescent host materials in the light-emitting layer is still unsatisfactory in terms of half-life, efficiency and driving voltage for industrial practical use. In addition, in order to present the excellent performance of organic EL devices, the phosphorescent host material needs to be coordinated with other organic thin film layers (e.g., hole blocking layer and electron transport layer) to achieve low energy consumption, long half-life and high efficiency. Therefore, it is necessary to design and develop new materials for organic EL devices. Summary of the invention

[0007] Purpose of the invention: In order to delay the half-life of the dipole material of the delayed fluorescence compound in the organic EL device, improve the efficiency and display performance, the present invention provides a delayed fluorescence compound based on an aryl oxadiazole unit and its preparation method and application. The organic electroluminescent device using the delayed fluorescence compound shows excellent performance in thermal stability, high luminous efficiency and long decay period.

[0008] The delayed fluorescence compound based on the aryl oxadiazole unit provided by the present invention has the following general structural formula:

[0009] Wherein, L1 and L2 are selected from any one of a single bond, an aryl group, and a heteroaryl group; X is selected from any one of S, Se, and Te; Y is selected from any one of C and N; Ar1 ​​and Ar5 are independently selected from C6~C30 substituted or unsubstituted aryl groups, C3~C30 substituted or unsubstituted heteroaryl groups; at least two of Ar2, Ar3, and Ar4 are naphthyl groups; at least two of Ar6, Ar7, and Ar8 are naphthyl groups.

[0010] Further, Ar1 and Ar5 are each independently selected from any one of the following groups: .

[0011] Wherein, Ar9 is selected from C6~C20 aryl or substituted aryl, C4~C20 heteroaryl or substituted heteroaryl, and h=an integer of 0~4.

[0012] Furthermore, the delayed fluorescence compound includes but is not limited to the following compounds: ; ; ; ; ; ; ; ; ; ; .

[0013] The present invention also provides a method for preparing a delayed fluorescence compound. The method uses a series of benzo[c][1,2,5-]-thiadiazole unit skeletons as donors and connects them with the donor characteristics of a series of units such as indolecarbazole to prepare the delayed fluorescence compound.

[0014] 1) In the structure of the delayed fluorescence compound, When the substitution structures on the left and right sides are the same, the preparation method is shown in formula (2):

[0015] 2) In the structure of the delayed fluorescence compound, When the substitution structures on the left and right sides are different, the preparation method is as shown in formula (3) or formula (4):

[0016] .

[0017] The delayed fluorescence compound of the present invention can be used in an organic electroluminescent device, which includes, from bottom to top, a transparent electrode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and a metal electrode. The light-emitting layer includes a phosphorescent host and a delayed fluorescence dopant material; the delayed fluorescence compound is used as a phosphorescent host or a delayed fluorescence dopant material.

[0018] Furthermore, the delayed fluorescence compound is used as a host material of an electron transport layer and / or a hole blocking layer.

[0019] Beneficial Effects 1) The present invention connects indolecarbazole and aryl[1,2,5-]-thiadiazole units through a single bond, an aromatic group or a heteroaromatic group to construct a novel DAD system delayed fluorescence compound, wherein the difference between the singlet energy and the triplet energy of the delayed fluorescence compound is less than 0.25 eV.

[0020] This helps to optimize the charge transfer characteristics and is of great significance for improving the performance of optoelectronic devices; the synthesized DAD compound shows photoluminescence properties with high quantum yield and is an ideal electroluminescent material.

[0021] 2) When the delayed fluorescence compound prepared by the present invention is used as the phosphorescent luminescent host of the light-emitting layer, the electron transport layer, the hole blocking layer and the delayed fluorescence material of the light-emitting layer, the layer can have good charge carrier mobility and excellent service life, which can reduce the driving voltage and energy consumption of the organic EL device, increase the efficiency of the organic EL device and extend its half-life, and has economic advantages for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the organic EL device in Example 8.

[0023] Figure 2 This is the ultraviolet absorption spectrum of C1 in Example 1.

[0024] Figure 3 This is the ultraviolet absorption spectrum of C2 in Example 2.

[0025] Figure 4 This is the fluorescence lifetime test graph of C1 in Example 1.

[0026] Figure 5 This is the fluorescence lifetime test graph of C2 in Example 2.

[0027] Figure 6 This is the H NMR spectrum of C1 in Example 1.

[0028] Figure 7 This is the H NMR spectrum of C2 in Example 2. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in detail below through embodiments, but the protection scope of the present invention is not limited to the embodiments.

[0030] Examples 1 to 7 show preferred examples of preparing delayed fluorescence compounds in the present invention. Example 8 is an example of device preparation.

[0031] Example 1: Preparation of Compound C1 The synthetic route of compound C1 is as follows:

[0032] The specific preparation steps of compound C1 are as follows: 1) Preparation of intermediate C1-1, the experimental steps are as follows: C1-0 (20.0 mmol, 8.45 g) was dissolved in 50 mL DMF (dimethylformamide). Under nitrogen protection, diboric acid pinacol ester (24.0 mmol, 6.10 g), anhydrous potassium acetate (30.0 mmol, 3 g), catalyst (0.1 mmol, 73 mg) PdCl2 (dppf) and cuprous iodide (2.0 mmol, 380 mg) were added. The temperature was raised to 100 ° C, stirred for reaction for 12 hours, cooled to room temperature, diluted with 50 mL of water, extracted with ethyl acetate, collected the organic phase, dried, filtered, and the filtrate was concentrated under reduced pressure. Purification was performed using a silica gel column to obtain a yellow solid product C1-1 (8.8 g, yield 83%).

[0033] 2) Preparation of intermediate C1-2, the experimental steps are as follows: The product C1-1 (111 mmol, 52.1 g) of the previous step, 2-bromonitrobenzene (133 mmol, 26.9 g), potassium carbonate (333 mmol, 46.0 g), and Pd(PPh3)4 (6.66 mmol, 7.7 g) were mixed and added to a flask, and then THF (490 mL) and water (245 mL) were added, and refluxed at 80°C for 12 hours. After the reaction was completed, the reactant was cooled to room temperature, extracted with dichloromethane and washed with water. The organic layer was dried and concentrated with magnesium sulfate, and separated by silica gel column chromatography to obtain the product C1-2 (25.8 g, yield 68%).

[0034] 3) Preparation of intermediate C1-3, the experimental steps are as follows: The product C1-2 (56 mmol, 26.1 g) from the previous step and triphenylphosphine (141 mmol, 37 g) were dissolved in 240 mL of o-dichlorobenzene and refluxed at 180°C for 24 hours. When the reaction was completed, the solvent was removed by vacuum distillation, and the product was concentrated and passed through a silica gel column and recrystallized to obtain the product C1-3 (12.0 g, yield 72%). 4) Preparation of compound C1, the experimental steps are as follows: In nitrogen, a mixture of (5.0 g, 17.0 mmol) 4,7-dibromobenzo[c][1,2,5]thiadiazole, intermediate C1-3 (19.1 g, 44.2 mmol), (0.3 g, 0.16 mmol) copper iodide, (0.1 g, 0.51 mmol) 18-crown-6, (9.5 g, 68.4 mmol) potassium carbonate and 25 ml NMP (N-methylpyrrolidone) was refluxed at 202°C overnight. After the reaction was completed, the mixture was cooled to room temperature. The solution was poured into water and then filtered. The solid was recrystallized using DMF (dimethylformamide) and purified by sublimation to obtain the product C1 (4.0 g, yield 32%). The mass spectrometry analysis of C1 showed: MS (m / z, FAB+): 997.17. The UV absorption spectrum of C1 is shown in the figure below. Figure 2 As shown, the fluorescence lifetime test graph of C1 is as follows Figure 4 As shown, the H NMR spectrum of C1 is as follows Figure 6 shown.

[0035] Example 2: Preparation of Compound C2 The synthetic route of compound C2 is as follows:

[0036] The specific preparation steps of compound C2 are as follows: 1) Preparation of intermediate C2-1, the experimental steps are as follows: C2-0 (20.0 mmol, 9.0 g) was dissolved in 50 mL DMF (dimethylformamide). Under nitrogen protection, diboric acid pinacol ester (24.0 mmol, 6.10 g), anhydrous potassium acetate (30.0 mmol, 3 g), catalyst (0.1 mmol, 73 mg) PdCl2 (dppf) and cuprous iodide (2.0 mmol, 380 mg) were added. The temperature was raised to 100 ° C, stirred for 12 hours, cooled to room temperature, diluted with 50 mL of water, extracted with ethyl acetate, collected the organic phase, dried, filtered, and the filtrate was concentrated under reduced pressure. Purification was performed using a silica gel column to obtain a yellow solid product C2-1 (9.1 g, yield 81%).

[0037] 2) Preparation of intermediate C2-2, the experimental steps are as follows: The product C2-1 (111 mmol, 55.2 g) of the previous step, 2-bromonitrobenzene (133 mmol, 26.9 g), potassium carbonate (333 mmol, 46.0 g), and Pd(PPh3)4 (6.66 mmol, 7.7 g) were mixed and added to a flask, and then THF (490 mL) and water (245 mL) were added, and refluxed at 80°C for 12 hours. After the reaction was completed, the reactant was cooled to room temperature, extracted with dichloromethane and washed with water. The organic layer was dried and concentrated with magnesium sulfate, and separated by silica gel column chromatography to obtain the product C2-2 (28.6 g, yield 68%).

[0038] 3) Preparation of intermediate C2-3, the experimental steps are as follows: The product C2-2 (56 mmol, 27.6 g) from the previous step and triphenylphosphine (141 mmol, 37 g) were dissolved in 240 mL of o-dichlorobenzene and refluxed at 180°C for 24 hours. When the reaction was completed, the solvent was removed by vacuum distillation, and the concentrated product was passed through a silica gel column and recrystallized to obtain the product C2-3 (13.4 g, yield 68%).

[0039] 4) Preparation of compound C2, the experimental steps are as follows: In nitrogen, a mixture of (7.82 g, 17.0 mmol) 4,7-dibromobenzo[c][1,2,5]thiadiazole, intermediate C2-3 (20.4 g, 44.2 mmol), (0.3 g, 0.16 mmol) copper iodide, (0.1 g, 0.51 mmol) 18-crown-6, (9.5 g, 68.4 mmol) potassium carbonate and 25 ml NMP (N-methylpyrrolidone) was refluxed at 202°C overnight. After the reaction was completed, the mixture was cooled to room temperature. The solution was poured into water and then filtered. The solid was recrystallized using DMF (dimethylformamide) and purified by sublimation to obtain the product C2 (4.2 g, yield 30%). The mass spectrometry analysis of C2 showed: MS (m / z, FAB+): 1053.28. The ultraviolet absorption spectrum of C2 is shown in the figure below. Figure 3 As shown, the fluorescence lifetime test graph of C2 is as follows Figure 5 As shown, the H NMR spectrum of C2 is as follows Figure 7 shown.

[0040] Example 3: Preparation of Compound C5 The synthetic route of compound C5 is as follows:

[0041] The specific preparation steps of compound C5 are as follows: 1) Preparation of intermediate C5-1, the experimental steps are as follows: C5-0 (20.0 mmol, 6.9 g) was dissolved in 50 mL DMF (dimethylformamide). Under nitrogen protection, diboric acid pinacol ester (24.0 mmol, 6.10 g), anhydrous potassium acetate (30.0 mmol, 3 g), catalyst (0.1 mmol, 73 mg) PdCl2 (dppf) and cuprous iodide (2.0 mmol, 380 mg) were added. The temperature was raised to 100 ° C, stirred for reaction for 12 hours, cooled to room temperature, diluted with 50 mL of water, extracted with ethyl acetate, collected the organic phase, dried, filtered, and the filtrate was concentrated under reduced pressure. Purification was performed using a silica gel column to obtain the product C5-1 (7.1 g, yield 84%).

[0042] 2) Preparation of intermediate C5-2, the experimental steps are as follows: The product C5-1 (111 mmol, 43.65 g) of the previous step, 2-bromonitrobenzene (133 mmol, 26.9 g), potassium carbonate (333 mmol, 46.0 g), and Pd(PPh3)4 (6.66 mmol, 7.7 g) were mixed and added to a flask, and then THF (490 mL) and water (245 mL) were added, and refluxed at 80°C for 12 hours. After the reaction was completed, the reactant was cooled to room temperature, extracted with dichloromethane and washed with water. The organic layer was dried and concentrated with magnesium sulfate, and separated by silica gel column chromatography to obtain the product C5-2 (27.5 g, yield 64.7%).

[0043] 3) Preparation of intermediate C5-3, the experimental steps are as follows: The product C5-2 (56 mmol, 21.75 g) from the previous step and triphenylphosphine (141 mmol, 37 g) were dissolved in 240 mL of o-dichlorobenzene and refluxed at 180°C for 24 hours. When the reaction was completed, the solvent was removed by vacuum distillation, and the concentrated product was passed through a silica gel column and recrystallized to obtain the product C5-3 (10.8 g, yield 64%).

[0044] 4) Preparation of compound C5-4, the experimental steps are as follows: Under nitrogen protection, the product C5-3 (30 mmol, 10.7 g) from the previous step, bromobenzene (33 mmol, 5.2 g), Pd2(dba)3 (0.90 mmol, 0.82 g) and sodium tert-butoxide (90.24 mmol, 8.67 g) were mixed and dissolved in 300 mL toluene and refluxed at 100°C for 8 h. After the reaction, the mixture was cooled to room temperature, extracted with dichloromethane, and the organic phase was dried over anhydrous sodium sulfate. The product C5-4 (8.7 g, yield 64%) was obtained by column chromatography.

[0045] 5) Preparation of compound C5, the experimental steps are as follows: A mixture of (7.82 g, 17.0 mmol) 4,7-dibromobenzo[c][1,2,5]thiadiazole, intermediate C5-4 (19.1 g, 44.2 mmol), (0.3 g, 0.16 mmol) copper iodide, (0.1 g, 0.51 mmol) 18-crown-6, (9.5 g, 68.4 mmol) potassium carbonate and 25 ml NMP (N-methylpyrrolidone) was refluxed at 202°C overnight in nitrogen. After the reaction was completed, the mixture was cooled to room temperature. The solution was poured into water and then filtered. The solid was recrystallized using DMF (dimethylformamide) and purified by sublimation to obtain the product C5 (4.2 g, 34% yield). The mass spectrometry analysis of C5 showed: MS (m / z, FAB+): 997.17.

[0046] Example 4: Preparation of Compound C9 The synthetic route of compound C9 is as follows:

[0047] 1) Preparation of intermediate C9-1, the experimental steps are as follows: C9-0 (20.0 mmol, 7.4 g) was dissolved in 50 mL DMF (dimethylformamide). Under nitrogen protection, diboric acid pinacol ester (24.0 mmol, 6.10 g), anhydrous potassium acetate (30.0 mmol, 3 g), catalyst (0.1 mmol, 73 mg) PdCl2 (dppf) and cuprous iodide (2.0 mmol, 380 mg) were added. The temperature was raised to 100 ° C, stirred for 12 hours, cooled to room temperature, diluted with 50 mL of water, extracted with ethyl acetate, collected the organic phase, dried, filtered, and the filtrate was concentrated under reduced pressure. Purification was performed using a silica gel column to obtain the product C9-1 (9.4 g, yield 86.5%).

[0048] 2) Preparation of intermediate C9-2, the experimental steps are as follows: The product C9-1 (111 mmol, 45.0 g) of the previous step, 2-bromonitrobenzene (133 mmol, 26.9 g), potassium carbonate (333 mmol, 46.0 g), and Pd(PPh3)4 (6.66 mmol, 7.7 g) were mixed and added to a flask, and then THF (490 mL) and water (245 mL) were added, and refluxed at 80°C for 12 hours. After the reaction was completed, the reactant was cooled to room temperature, extracted with dichloromethane and washed with water. The organic layer was dried and concentrated with magnesium sulfate, and separated by silica gel column chromatography to obtain the product C9-2 (38.5 g, yield 62%).

[0049] 3) Preparation of intermediate C9-3, the experimental steps are as follows: The product C9-2 (56 mmol, 26.0 g) from the previous step and triphenylphosphine (141 mmol, 37 g) were dissolved in 240 mL of o-dichlorobenzene and refluxed at 180°C for 24 hours. When the reaction was completed, the solvent was removed by vacuum distillation, and the concentrated product was passed through a silica gel column and recrystallized to obtain the product C9-3 (12.3 g, yield 67%).

[0050] 4) Preparation of intermediate C9, the experimental steps are as follows: A mixture of (7.82 g, 17.0 mmol) 4,7-dibromobenzo[c][1,2,5]thiadiazole, intermediate C9-3 (19.1 g, 44.2 mmol), (0.3 g, 0.16 mmol) copper iodide, (0.1 g, 0.51 mmol) 18-crown-6, (9.5 g, 68.4 mmol) potassium carbonate and 25 ml NMP (N-methylpyrrolidone) was refluxed at 202°C overnight in nitrogen. After the reaction was completed, the mixture was cooled to room temperature. The solution was poured into water and then filtered. The solid was recrystallized using DMF (dimethylformamide) and purified by sublimation to obtain the product C9 (3.7 g, 31% yield). The mass spectrometry analysis of C5 showed: MS (m / z, FAB+): 997.17.

[0051] Example 5: Preparation of Compound C25 The synthetic route of compound C25 is as follows:

[0052] 1) Preparation of intermediate C25-1, the experimental steps are as follows: Experimental steps: C25-0 (20.0 mmol, 8.45 g) was dissolved in 50 mL DMF (dimethylformamide). Under nitrogen protection, diboric acid pinacol ester (24.0 mmol, 6.10 g), anhydrous potassium acetate (30.0 mmol, 3 g), catalyst (0.1 mmol, 73 mg) PdCl2 (dppf) and cuprous iodide (2.0 mmol, 380 mg) were added. The temperature was raised to 100 ° C, stirred for 12 hours, cooled to room temperature, diluted with 50 mL of water, extracted with ethyl acetate, collected the organic phase, dried, filtered, and the filtrate was concentrated under reduced pressure. Purification was performed using a silica gel column to obtain a yellow solid product C25-1 (8.8 g, yield 83%).

[0053] 2) Preparation of intermediate C25-2, the experimental steps are as follows: The product C25-1 (111 mmol, 52.1 g) of the previous step, 2-bromonitrobenzene (133 mmol, 26.9 g), potassium carbonate (333 mmol, 46.0 g), and Pd(PPh3)4 (6.66 mmol, 7.7 g) were mixed and added to a flask, and then THF (490 mL) and water (245 mL) were added, and refluxed at 80°C for 12 hours. After the reaction was completed, the reactant was cooled to room temperature, extracted with dichloromethane and washed with water. The organic layer was dried and concentrated with magnesium sulfate, and separated by silica gel column chromatography to obtain the product C25-2 (25.8 g, yield 68%).

[0054] 3) Preparation of intermediate C25-3, the experimental steps are as follows: Experimental steps: The product C25-2 (56 mmol, 26.1 g) and triphenylphosphine (141 mmol, 37 g) from the previous step were dissolved in 240 mL of o-dichlorobenzene and refluxed at 180°C for 24 hours. When the reaction was completed, the solvent was removed by vacuum distillation, and the concentrated product was passed through a silica gel column and recrystallized to obtain the product 25-3 (12.0 g, yield 72%). 4) Preparation of intermediate C25-4, the experimental steps are as follows: Experimental procedure: A mixture of (4.0 g, 17.0 mmol) 1,4-dibromobenzene, intermediate C25-3 (18.1 g, 44.2 mmol), (0.3 g, 0.16 mmol) copper iodide, (0.1 g, 0.51 mmol) 18-crown-6, (9.5 g, 68.4 mmol) potassium carbonate and 25 ml NMP (N-methylpyrrolidone) was refluxed at 202 °C for 8 hours in nitrogen. After the reaction was completed, the mixture was cooled to room temperature. The solution was poured into water and then filtered. The solid was recrystallized using DMF (dimethylformamide) and purified by sublimation to obtain the product C25-4 (7.3 g, 56% yield).

[0055] 5) Preparation of intermediate C25-5, the experimental steps are as follows: Experimental steps: C25-4 (20.0 mmol, 11.75 g) was dissolved in 50 mL DMF (dimethylformamide). Under nitrogen protection, diboric acid pinacol ester (24.0 mmol, 6.10 g), anhydrous potassium acetate (30.0 mmol, 3 g), catalyst (0.1 mmol, 73 mg) PdCl2 (dppf) and cuprous iodide (2.0 mmol, 380 mg) were added. The temperature was raised to 100 ° C, stirred for 12 hours, cooled to room temperature, diluted with 50 mL of water, extracted with ethyl acetate, collected the organic phase, dried, filtered, and the filtrate was concentrated under reduced pressure. Purification was performed using a silica gel column to obtain the product C25-5 (6.8 g, yield 46%).

[0056] 6) Preparation of compound C25, the experimental steps are as follows: Experimental steps: Under nitrogen protection, the product C25-5 (40 mmol, 25.37 g) of the previous step, 4,7-dibromobenzo[c][1,2,5]thiadiazole (40 mmol, 18.1 g), potassium carbonate (80 mmol, 11.1 g) and catalyst tetrakistriphenylphosphine palladium (1 mmol, 1.15 g) were mixed and dissolved in 350 mL solvent (volume ratio, toluene: water = 4:1), refluxed at 110 ° C for 8 hours, and after the reaction was completed, cooled to room temperature, extracted with dichloromethane, and the organic phase was dried with magnesium sulfate. After column chromatography separation, the product C25 (45.2 g, yield 76%) was obtained. The mass spectrometry analysis of C25 showed: MS (m / z, FAB+): 1149.36.

[0057] Example 6: Preparation of Compound C43 The synthetic route of compound C43 is as follows:

[0058] The synthetic steps of C43-0 and C43-2 refer to Example 1 and Example 3 1) Preparation of intermediate C43-1. The specific experimental steps are as follows: A mixture of (7.82 g, 17.0 mmol) 4,7-dibromobenzo[c][1,2,5]thiadiazole, intermediate C43-0 (19.1 g, 44.2 mmol), (0.3 g, 0.16 mmol) copper iodide, (0.1 g, 0.51 mmol) 18-crown-6, (9.5 g, 68.4 mmol) potassium carbonate and 25 ml NMP (N-methylpyrrolidone) was refluxed at 202 °C overnight under nitrogen. After the reaction was completed, the mixture was cooled to room temperature. The solution was poured into water and then filtered. The solid was recrystallized using DMF (dimethylformamide) and purified by sublimation to obtain the product (6.8 g, 43% yield).

[0059] 2) Preparation of compound C43. The specific experimental steps are as follows: In nitrogen, a mixture of (11.2 g, 17.0 mmol) C43-2, intermediate C43-1 (18.1 g, 44.2 mmol), (0.3 g, 0.16 mmol) copper iodide, (0.1 g, 0.51 mmol) 18-crown-6, (9.5 g, 68.4 mmol) potassium carbonate and 25 ml NMP (N-methylpyrrolidone) was refluxed at 202°C overnight. After the reaction was completed, the mixture was cooled to room temperature. The solution was poured into water and then filtered. The solid was recrystallized using DMF (dimethylformamide) and purified by sublimation to obtain the product C43 (5.1 g, yield 36%). The mass spectrometry analysis of C43 showed: MS (m / z, FAB+): 997.17.

[0060] Example 7: Preparation of Compound C48 The synthetic route of compound C48 is as follows:

[0061] For the synthesis of intermediate C48-0 and intermediate C48-2, please refer to Example 5 1) Preparation of intermediate C48-1. The specific experimental steps are as follows: Under nitrogen protection, C48-0 (40 mmol, 25.37 g), 4,7-dibromobenzo[c][1,2,5]thiadiazole (40 mmol, 18.1 g), potassium carbonate (80 mmol, 11.1 g) and catalyst tetrakistriphenylphosphine palladium (1 mmol, 1.15 g) were mixed and dissolved in 350 mL solvent (toluene: water = 4:1), refluxed at 110 ° C for 8 hours, and after the reaction was completed, cooled to room temperature, extracted with dichloromethane, and the organic phase was dried with magnesium sulfate. The product (31.2 g, yield 67%) was obtained after column chromatography separation.

[0062] 2) Preparation of compound C48. The specific experimental steps are as follows: Under nitrogen protection, the products C48-1 (40 mmol, 28.86 g), C48-2 (40 mmol, 25.3 g), potassium carbonate (80 mmol, 11.1 g) and catalyst tetrakistriphenylphosphine palladium (1 mmol, 1.15 g) from the previous step were mixed and dissolved in 350 mL of solvent (toluene: water = 4:1), refluxed at 110 ° C for 8 hours, and after the reaction was completed, cooled to room temperature, extracted with dichloromethane, and the organic phase was dried with magnesium sulfate. After column chromatography separation, the product C48 (38 g, yield 56%) was obtained. The mass spectrometry analysis of C48 showed: MS (m / z, FAB+): 1149.36.

[0063] Example 8: Preparation of an organic EL device General method for producing organic EL devices: Indium Tin Oxide (ITO) coated glass with a resistance of 9 to 12 ohms / m2 and a thickness of 120 to 160 nm is cleaned several times in an ultrasonic bath (e.g., detergent, plasma water). The cleaned ITO coated glass is further treated with ultraviolet light (UV) and ozone before vapor deposition of the organic layer. All pretreatment processes of the ITO substrate are carried out in a clean room (class 100). The organic layer is passed through a high vacuum unit (10 - 7 Torr) vapor deposition method is applied to the ITO substrate in sequence, such as: resistance heating quartz boat. The thickness of each layer and the vapor deposition rate (0.1-0.3 nm / sec) are accurately monitored or set by a quartz crystal monitor. It is also possible to make a single layer contain more than one compound, that is, doping materials are doped in the general host material, and deposition is achieved by co-vapor method from two or more sources.

[0064] The organic EL device prepared in this embodiment has a structure as shown in FIG. Figure 1 As shown, the organic EL device includes a transparent electrode I and a metal electrode Q, and between the two electrodes are a hole injection layer J deposited on the transparent electrode I, a hole transport layer K deposited on the hole injection layer J, an electron blocking layer L deposited on the hole transport layer K, a light-emitting layer M deposited on the electron blocking layer L, a hole blocking layer N deposited on the light-emitting layer M, an electron transport layer O deposited on the hole blocking layer N, an electron injection layer P deposited on the electron transport layer O, and a metal electrode Q deposited on the electron injection layer P.

[0065] In organic EL devices: 1) Transparent electrode I, using ITO substrate.

[0066] 2) The hole injection layer J uses m-MTDATA (4,4',4'' - tris(3-methylphenylphenylamino)triphenylamine) with the following structural formula:

[0067] 3) The hole transport layer K is NPB (N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine) with the following structure:

[0068] 4) Electron blocking layer L: N-(biphenyl-4-yl)-9,9-dimethyl-N-(4'-phenyl biphenyl-4-yl)-9H-fluoren-2-amine (EB2) was used as an electron blocking layer. The structural formula of EB2 is as follows:

[0069] 5) Luminous layer M: The light-emitting layer M is composed of a phosphorescent host and a delayed fluorescence dopant. Compound S1, C1 and C2 prepared in Example 1-2 are respectively used as the phosphorescent hosts of the light-emitting layer, and different contents of compound T, C1, C2, C5, C9 prepared in Example 1-4, and Ir(ppy)3 are doped in the host respectively as a delayed fluorescence dopant. Compound S1 is used as the phosphorescent host of the light-emitting layer for comparison with the compound prepared in this example. The structural formulas of S1, T, and Ir(ppy)3 are as follows: 6) Hole blocking layer N: C2, 2,2,2"-(1,3,5-Benzinetriazine)-tris(1-phenyl-1-H-benzimidazole) (TPBi) or HB3 prepared in Example 2 was used as a hole blocking material (HBM). The structural formulas of TPBi and HB3 are as follows: 7) Electron transport layer O: C1, C2 or 2-(10,10-dimethyl-10H-indeno[2,1-b]triphenylen-12-yl)-4,6-diphenyl-1,3,5-triazine (ET2) prepared in Example 1-2 is used as an electron transport material. In this embodiment, the electron transport layer O is doped with 40% 8-hydroxyquinolato-lithium (8-hydroxyquinolato-lithium, LiQ) during deposition. The structural formulas of ET2 and LiQ are as follows:

[0070] 8) Electron injection layer P: The existing electron injection layer material is a metal halide or metal oxide with a low work function, such as LiF, LiQ, MgO or Li2O. In this embodiment, LiQ is selected.

[0071] 9) Metal electrode Q: In this embodiment, Al is selected.

[0072] Organic EL devices generally include a low work function metal such as Al, Mg, Ca, Li and K, which is formed into a cathode by thermal evaporation, and the low work function metal can help inject electrons from the cathode into the electron transport layer. In addition, a thin film electron injection layer is introduced between the cathode and the electron transport layer to reduce the electron injection barrier and improve the performance of the organic EL device.

[0073] After the organic EL device was fabricated, the EL spectrum and CIE coordinates were measured by using a PR650 spectrum scanning spectrometer. In addition, the current / voltage, luminescence / voltage, and yield / voltage characteristics were detected using a Keithley 2400 programmable voltage-current source. The above equipment was operated at room temperature (about 25° C.) and atmospheric pressure.

[0074] The organic EL device prepared in this embodiment is specifically: ITO / m-MTDATA (20 nm) / NPB (110 nm) / EB2 (5 nm) / host + 10% to 30% dopant (30 nm) / HBM (10 nm) / ETM doped 40% LiQ (35 nm) / LiQ (1nm) / Al (160 nm); the parameters of the organic EL device and the test report results of IVB (at 1000nits brightness) are shown in Table 1.

[0075] Table 1

[0076]

[0077] In the preferred embodiment of the above-mentioned organic EL device test report (see Table 1), it is disclosed that when the delayed fluorescence compound having the structure of formula (1) in the present invention is used as the phosphorescent host of the light-emitting layer, electron transport layer, hole blocking layer or the delayed fluorescence (TADF) material of the light-emitting layer of the organic EL device device, the performance of the organic EL device of the present invention is better than that of the prior art organic EL material.

[0078] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to the form and details without departing from the spirit and scope of the present invention.

Claims

1. A delayed fluorescence compound based on an aryl oxadiazole unit, characterized in that: The general structural formula of the delayed fluorescence compound is as follows: ； Wherein, L1 and L2 are selected from any one of a single bond, an aryl group, and a heteroaryl group; X is selected from any one of S, Se, and Te; Y is selected from any one of CH and N; Ar1 ​​and Ar5 are independently selected from C6~C30 substituted or unsubstituted aryl groups, C3~C30 substituted or unsubstituted heteroaryl groups; at least two of Ar2, Ar3, and Ar4 are naphthyl groups; at least two of Ar6, Ar7, and Ar8 are naphthyl groups.

2. The delayed fluorescence compound according to claim 1, characterized in that Ar1 and Ar5 are each independently selected from any one of the following groups: ； Wherein, Ar9 is selected from C6-C20 aryl or substituted aryl, C4-C20 heteroaryl or substituted heteroaryl, and h is an integer of 0-4.

3. The delayed fluorescence compound according to claim 1, characterized in that Includes the following compounds: ； ； ； ； ； ； ； ； ； ； 。 4. The method for preparing the delayed fluorescence compound according to claim 1, characterized in that: In the structure of the delayed fluorescence compound, When the substitution structures on the left and right sides are the same, the preparation method is shown in formula (2): ； In the structure of the delayed fluorescence compound, When the substitution structures on the left and right sides are different, the preparation method is as shown in formula (3) or formula (4): ； 。 5. The use of the delayed fluorescence compound according to claim 1, characterized in that: The delayed fluorescence compound is used for preparing an organic electroluminescent device.

6. The use according to claim 5, characterized in that: The organic electroluminescent device comprises, from bottom to top, a transparent electrode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and a metal electrode; The light-emitting layer includes a phosphorescent host and a delayed fluorescence doping material; the delayed fluorescence compound is used as the phosphorescent host or the delayed fluorescence doping material.

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