Thermal activation delayed fluorescence luminescent material based on benzoxazole ring core as well as preparation method and application of thermal activation delayed fluorescence luminescent material

Abstract

The invention discloses a thermally activated delayed fluorescence luminescent material based on a benzoxazole ring core as well as a preparation method and application thereof, and belongs to the technical field of organic photoelectric semiconductors. According to the thermal activation delayed fluorescence luminescent material prepared by the invention, the electron cloud overlapping between a donor and a receptor can be effectively regulated and controlled through the structure and the combination mode of the donor unit in the molecule, the energy level, the band gap and the triplet state excited state energy level are remarkably influenced, and the singlet state and triplet state energy level difference is improved; in addition, dihedral angles are respectively formed between the bridging unit and the donor unit and between the bridging unit and the acceptor unit in the molecule, so that molecular accumulation and aggregation state luminescence behaviors are promoted and improved. The thermally activated delayed fluorescence luminescent material prepared by the invention has better thermal stability, higher photoluminescence quantum efficiency, smaller delta EST and high reverse intersystem transition rate, and has wide application prospects in the fields of organic semiconductor devices, biology, sensing and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic photoelectric semiconductors, and in particular is a thermally activated delayed fluorescence luminescent material based on a benzoxazole ring core, and a preparation method and application thereof. Background Art

[0002] Organic light-emitting diodes (OLEDs) are considered to be the most promising display and lighting technology. A typical OLED consists of a glass substrate, ITO, an anode, an organic light-emitting layer and a cathode, among which the light-emitting material is the most important factor determining the luminous efficiency of OLEDs. The development of OLED light-emitting materials has gone through the fluorescent material stage, the phosphorescent material stage and the latest thermally activated delayed fluorescence stage (TADF). The first type of fluorescent material can only utilize 25% of the singlet S1 excitons, which causes a great loss of quantum efficiency during the operation of the device. The second generation of phosphorescent materials can theoretically achieve 100% internal quantum efficiency because they utilize 75% of the triplet energy. Compared with the first generation of fluorescent materials, phosphorescent materials have significant technical advantages, which are conducive to reducing device power consumption, reducing heat generation, improving device stability and extending device service life. However, Ir-type phosphorescent materials are not only expensive, but also pollute the environment. In the prior art, a type of pure organic molecules with electron donors and acceptors connected vertically in the plane have very small triplet and singlet energy band gaps (ΔE ST ), so that 75% of the triplet states that cannot be used by small molecules to emit light are utilized, and the electrons in the triplet state can efficiently return to the singlet state through reverse intersystem crossing, and then jump from the singlet state back to the ground state and emit fluorescence. ST Even if it is very small, electrons need an external force to jump from the triplet state to the singlet state. This external force is heat, and the whole process is called thermally activated delayed fluorescence (TADF).

[0003] The current mainstream TADF organic material design principle is to reduce the overlap between the HOMO and LUMO orbitals of the molecule, thereby reducing the energy level difference ΔE between S1 and T1. ST Benzimidazole molecules, due to their good thermal stability and unique photophysical properties, are used as a good receptor material in organic optoelectronic devices such as organic field-effect transistors, organic photovoltaic cells and organic sensors. Summary of the invention

[0004] The present invention provides a thermally activated delayed fluorescence luminescent material based on a benzoxazole ring core and a preparation method and application thereof, so as to obtain an organic light-emitting device with more favorable performance, richer structure, easier functionalization and large-scale production.

[0005] Technical solution: A thermally activated delayed fluorescence luminescent material based on a benzoxazole ring core, wherein the thermally activated delayed fluorescence luminescent material is a compound represented by the general formula (I):

[0006] Wherein, X is O, S, Se, NR or , R is selected from a C1-C24 straight chain or branched alkyl group, a substituted C6-C30 aryl group, or a C5-C30 heteroaryl group; R1 and R2 are selected from a substituted C6-C30 aryl group, or a C5-C30 heteroaryl group; L1 and L2 are single bonds or arylene groups; Y is CH or N; Ar1 ​​and Ar2 are each independently an aryl group connected to L1 and L2 via a N atom, and at least one of them is a structure represented by the general formula (II);

[0007] In the general formula (II), Ar3 and Ar4 are independently selected from a substituted or unsubstituted benzene ring, a naphthalene ring, a thiophene ring, a benzothiophene ring, a benzofuran, an anthracene ring, a phenanthrene ring, and a pyrene ring.

[0008] Preferably, Ar3 and Ar4 are each independently one of the following formulae:

[0009] Wherein, R3 represents a substituent on Ar3 and Ar4, n is selected from an integer of 0-4, representing 0-4 substituents represented by R3, m is selected from an integer of 0-2, representing 0-2 substituents represented by R3; R3 is independently selected from deuterium, halogen, cyano, C1-C10 alkyl, C1-C10 alkoxy, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C30 heteroaryl. When n≥2, each R3 is the same or different.

[0010] Preferably, in the thermally activated delayed fluorescent luminescent material, and Each is independently one of the following:

[0011] .

[0012] Preferably, the thermally activated delayed fluorescent luminescent material comprises the following compounds:

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021] .

[0022] The thermally activated delayed fluorescent luminescent material of the present invention can be used to prepare an organic electroluminescent device, which includes an anode, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer and a cathode stacked in sequence on a substrate; the organic light-emitting layer includes a host material and a guest material, and the guest material includes one or two of the thermally activated delayed fluorescent luminescent materials. In the perovskite solar cell composition of the perovskite solar cell device, the thermally activated delayed luminescent molecule is used as a hole transport layer.

[0023] The method for preparing the thermally activated delayed fluorescent luminescent material includes the following six situations: (1) When L1 and L2 are single bonds and Ar1 and Ar2 are the same, the preparation reaction equation is: ; The specific steps are as follows: Step 1.1: Under nitrogen atmosphere, and , added to acetic acid solvent, stirred at 60°C for 5 hours, after the reaction was completed, the reaction solution was cooled to room temperature, and ammonia solution was added dropwise to neutralize it under stirring until the pH was 7, the precipitate was filtered, washed with acetic acid, and then recrystallized with ethanol to obtain the compound ; Step 1.2, the compound obtained in step 1.1, , catalyst (potassium carbonate, cuprous iodide, o-phenanthroline, 18-crown ether-6), added to solvent N,N-dimethylformamide, condensed and refluxed at 180°C for 12 hours, after the reaction was completed, the reaction was cooled to room temperature, the reaction solution was poured into brine, filtered to obtain a crude product, and then purified by silica gel column chromatography to obtain compound .

[0024] (2) When L1 and L2 are single bonds and Ar1 and Ar2 are different, the preparation reaction equation is: ; The specific steps are as follows: Step 2.1, obtaining compounds Ar1 and Ar2 according to the method of step 1.1; Step 2.2, Ar1, , catalyst (potassium carbonate, cuprous iodide, o-phenanthroline, 18-crown ether-6), added to solvent N,N-dimethylformamide, condensed and refluxed at 180°C for 12 hours, after the reaction was completed, the reaction was cooled to room temperature, the reaction solution was poured into brine, filtered to obtain a crude product, and then purified by silica gel column chromatography to obtain compound ; Step 2.3, the compound obtained in step 2.2 and Ar2 are used to obtain a compound according to the method of step 2.2 .

[0025] (3) When L1 and L2 are the same arylene group, Ar5 represents an arylene group, and Ar1 and Ar2 are the same, the preparation reaction equation is: ; The specific steps are as follows: Step 3.1: , , according to step 2.2, compound ; Step 3.2: Add the compound obtained in step 3.1, bipyraclostrobin, and catalyst (potassium acetate, [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride) to the solvent 1,4-dioxane, reflux at 95°C for 12h, extract with dichloroethane and water, and spin-dry the organic phase to obtain the compound ; Step 3.3, the compound obtained in step 3.2, , catalyst (potassium carbonate, [1,1'-bis(diphenylphosphino)ferrocene] dichloropalladium dichloromethane complex), dissolved in solvent (tetrahydrofuran and water), stirred at 70°C for 3h. After the reaction was completed, the reaction solution was cooled to room temperature, extracted with water and dichloromethane, and the organic phase was concentrated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain compound .

[0027] (4) When L1 and L2 are the same arylene group, Ar1 and Ar2 are different; or when L1 and L2 are different arylene groups, Ar5 and Ar6 represent arylene groups, and Ar1 and Ar2 are the same or different, the preparation reaction equation is: ; The specific steps are as follows: Step 4.1: Obtain the compound according to the method of steps 3.1 and 3.2 , ; Step 4.2: , , catalyst (potassium carbonate, [1,1'-bis(diphenylphosphino)ferrocene] dichloropalladium dichloromethane complex), dissolved in solvent (tetrahydrofuran and water), stirred at 70°C for 3h. After the reaction was completed, the reaction solution was cooled to room temperature, extracted with water and dichloromethane, and the organic phase was concentrated under reduced pressure to obtain a crude product, which was purified by silica gel column chromatography to obtain compound ; Step 4.3, the compound obtained in step 4.2, , according to step 4.2, compound ;

[0028] (5) When L1 is a single bond, L2 is an arylene group, Ar5 represents an arylene group, and Ar1 and Ar2 are the same or different, the preparation reaction equation is: ; The specific steps are as follows: Step 5.1: Obtain the compound according to the method of step 2.2 ; Step 5.2: Obtain the compound according to the method of steps 3.1 and 3.2 ; Step 5.3: , , according to step 4.2, compound .

[0029] (6) When L1 is an arylene group, L2 is a single bond, Ar5 represents an arylene group, and Ar1 and Ar2 are the same or different, the preparation reaction equation is:

[0030] The specific steps are as follows: Step 6.1: Obtain the compound according to the method of step 4.2 ; Step 6.2: , Ar2, according to step 2.2 method to obtain .

[0031] Beneficial effects: The compound of the present invention has a multiple DA structure with strong donor properties and strong acceptor properties, a high triplet energy level, a small ΔE ST, high PLQY, near-infrared luminescence, high stability and high glass transition temperature. Benzimidazole molecules have good thermal stability and unique photophysical properties. The arrangement of donor units in the molecule can effectively regulate the electron cloud overlap between the donor and the acceptor, significantly affecting the energy level, band gap and triplet excited state energy level, and improving the singlet and triplet energy level difference (ΔE ST ); on the other hand, the close-packed connection mode between the donor and the acceptor is affected by the dihedral angle of the bridging structure, which will obtain a better photoluminescence efficiency (PLQY). At the same time, the three-dimensional molecular structure of the donor part and the rigid planar large conjugated structure of the acceptor unit have an impact on its molecular crystallinity, and the stacking mode of the molecule in the aggregated state can be effectively regulated, so that the above-mentioned molecules have better morphological stability and excellent film stability in electroluminescent devices, which is beneficial to the corresponding device life and is beneficial to improving the performance and luminous efficiency of OLED devices. Multiple electron-rich donor units are conducive to obtaining high HOMO energy levels and balanced electron and hole transport properties, which is beneficial to its application in perovskite solar cell devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the structure of an organic electroluminescent device according to an embodiment of the present application. In which, 1. anode (ITO); 2. hole injection layer (HIL); 3. hole transport layer (HTL); 4. organic light emitting layer (EML); 5. electron transport layer (ETL); 6. electron injection layer (EIL); 7. cathode (Al); Figure 2 is the H NMR spectrum of compound A-1 of the present invention; Figure 3 It is the H NMR spectrum of compound B-4 of the present invention. DETAILED DESCRIPTION

[0033] 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.

[0034] In this specification, when no definition is provided in addition, "substituted" refers to that at least one hydrogen of a substituent or compound is replaced with deuterium, halogen, cyano, substituted or unsubstituted C1 to C24 alkyl, C3 to C24 cycloalkyl, C6 to C24 aryl, C2 to C24 heteroaryl or a combination thereof. In this specification, when no definition is provided in addition, "alkyl" refers to an aliphatic hydrocarbon group. The alkyl group can be a C1 to C24 alkyl group. More specifically, the alkyl group can be a C1 to C20 alkyl group or a C1 to C10 alkyl group. For example, the C1 to C4 alkyl group can have 1 to 4 carbon atoms in the alkyl chain and can be selected from methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl. The specific example of the alkyl group can be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl etc. In this specification, "aryl" refers to a group including at least one hydrocarbon aromatic part, and all elements of the hydrocarbon aromatic part have a p-orbital that forms a conjugation, such as phenyl, naphthyl, etc., two or more hydrocarbon aromatic parts can be connected by a σ bond and can be, for example, biphenyl, terphenyl, quaterphenyl, etc., or two or more hydrocarbon aromatic parts are directly or indirectly fused to provide a non-aromatic fused ring. For example, it can be fluorenyl. The aryl group can include a monocyclic, polycyclic or condensed polycyclic (i.e., a ring that shares adjacent carbon atoms) functional group. The compounds that do not mention the synthesis method in this embodiment can all be raw materials obtained through commercial channels.

[0035] Example 1: Preparation of the thermally activated delayed fluorescence luminescent material based on the benzoxazole ring core of the present invention (1) Preparation of Compounds 1 to 13 Synthesis route of compound 1:

[0036] Under nitrogen atmosphere, 2,3-diketo-indole (10 g, 68 mmol), 1,2-phenylenediamine (7.3 g, 68 mmol) and acetic acid (200 mL) were added to a 500 ml three-necked flask in sequence and stirred at 60°C for 5 hours. After the reaction was completed, the reaction solution was cooled to room temperature and ammonia solution was added dropwise to neutralize the reaction solution under stirring until the pH was 7. The precipitate was filtered, washed with acetic acid, and then recrystallized with ethanol to obtain 13.3 g (yield 89%) of pure compound 1, HR-MS (ACPI-M+, m / z): 219.080.

[0037] The compounds listed in Table 1 were synthesized in the same manner as compound 1, except that raw material 1 was used instead of 2,3-diketo-indole, and raw material 2 was used instead of 1,2-phenylenediamine, wherein the main raw materials used, the synthesized intermediates and their yields are shown in Table 1: Table 1

[0038] (2) Synthesis of compounds A-1, A-3, B-7, C-12, D-13, D-28, and E-5 The synthetic route of compound A-1 is as follows:

[0039] Under nitrogen atmosphere, 4,7-dibromobenzofuran (5g, 17.9mmol), compound 1 (9.8g, 44.8mmol), potassium carbonate (9.9g, 71.6mmol), cuprous iodide (3.8mg, 0.2mmol), o-phenanthroline (3.6mg, 0.2mmol), 18-crown ether-6 (5.3mmol, 0.2mmol) and dry N,N-dimethylformamide (200ml) were added to a 500ml three-necked flask in sequence. The mixture was refluxed at 180°C for 12h. After the reaction was completed, the reaction mixture was cooled to room temperature, the reaction solution was poured into 500ml 0.01M brine, and the crude product was obtained by filtration. The crude product was purified by silica gel column chromatography using a dichloromethane / hexanol (volume ratio 1:2.5) system to obtain 5.9 g (yield 60%) of pure compound A-1, HR-MS (ACPI-M+, m / z): 554.160, and the H NMR spectrum of compound A-1 is as follows Figure 2 shown.

[0040] The compounds listed in Table 2 were synthesized in the same manner as compound A-1, except that raw material 3 was used instead of compound 1, and raw material 4 was used instead of 4,7-dibromobenzofuran, wherein the main raw materials used, the synthesized intermediates and their yields are shown in Table 2: Table 2

[0041] (3) Preparation of Compounds 15 to 23 The synthetic route of compound 15 is as follows:

[0042] Under nitrogen atmosphere, compound 14 (CAS: 1380238-96-9, 5 g, 17.9 mmol), compound 4 (5.8 g, 21.5 mmol), potassium carbonate (9.9 g, 71.6 mmol), cuprous iodide (3.8 mg, 0.2 mmol), o-phenanthroline (3.6 mg, 0.2 mmol), 18-crown-6 (5.3 mmol, 0.2 mmol) and dry N,N-dimethylformamide (200 ml) were added to a 500 ml three-necked flask in sequence. The mixture was refluxed at 180°C for 12 h. After the reaction was completed, the reaction mixture was cooled to room temperature, the reaction solution was poured into 500 ml of 0.01 M brine, and the crude product was obtained by filtration. The crude product was purified by silica gel column chromatography using a dichloromethane / hexanol (volume ratio 1:2.5) system to obtain 5.0 g (yield 58%) of pure compound 15, HR-MS (ACPI-M+, m / z): 481.995.

[0043] The compounds listed in Table 3 were synthesized in the same manner as compound 15, except that raw material 5 was used instead of compound 4, and raw material 6 was used instead of compound 14. The main raw materials used, the synthesized intermediates and their yields are shown in Table 3: Table 3

[0044] (4) Synthesis of compounds B-4, A-4, A-14, C-11, C-29, and E-28 The synthetic route of compound B-4 is as follows:

[0045] Under nitrogen atmosphere, compound 15 (5g, 10.4mmol), compound 10 (3.4g, 12.5mmol), potassium carbonate (5.7g, 41.6mmol), cuprous iodide (1.9mg, 0.1mmol), o-phenanthroline (1.8mg, 0.1mmol), 18-crown ether-6 (2.7mg, 0.1mmol) and dry N, N-dimethylformamide (200ml) were added to a 500ml three-necked flask in sequence. Condensation reflux was carried out at 180°C for 12h. After the reaction was completed, the reaction was cooled to room temperature, the reaction solution was poured into 500ml of brine, and the crude product was filtered to obtain the crude product. The crude product was purified by silica gel column chromatography using a dichloromethane / hexanol (volume ratio 1:2.5) system to obtain 4.1g (yield 59%) of pure compound B-4, HR-MS (ACPI-M+, m / z): 671.164, and the nuclear magnetic hydrogen spectrum of compound B-4 is as follows Figure 3 shown.

[0046] The compounds listed in Table 4 were synthesized in the same manner as compound B-4, except that raw material 7 was used instead of compound 15, and raw material 8 was used instead of compound 10. The main raw materials used, the synthesized intermediates and their yields are shown in Table 4: Table 4

[0047] (5) Preparation of Compounds 24 to 26 The synthetic route of compound 24 is as follows:

[0048] Under nitrogen atmosphere, compound 21 (10 g, 24.5 mmol), bipyraclostrobin (8.7 g, 34.3 mmol), potassium acetate (7.2 g, 73.5 mmol), [1,1'-bis(diphenylphosphino)ferrocene] palladium dichloride (1.5 mg, 0.2 mmol) were added to a 500 ml three-necked flask in sequence and dissolved in 1,4-dioxane (200 ml). The mixture was refluxed at 95°C for 12 h. After the reaction was completed, it was extracted with dichloromethane and water. The organic phase was distilled under reduced pressure to remove the solvent to obtain a total of 9.14 g of compound 24 (yield 82%), HR-MS (ACPI-M+, m / z): 455.383.

[0049] The compounds listed in Table 5 were synthesized in the same manner as compound 24, except that raw material 9 was used instead of compound 21, wherein the main raw materials used, the synthesized intermediates and their yields are shown in Table 5: Table 5

[0050] (6) Preparation of Compound A-18 The synthetic route of compound A-18 is as follows:

[0051] Under nitrogen atmosphere, compound 24 (10 g, 22 mmol), compound 27 (13.4 g, 48.4 mmol), potassium carbonate (12.1 g, 88 mmol) and [1,1'-bis(diphenylphosphino)ferrocene] dichloropalladium dichloromethane complex (0.2 g, 0.2 mmol) were added to a 500 mL two-necked flask in sequence, and the solvent was 100 mL of tetrahydrofuran and 20 ml of water, and stirred at 70 ° C for 3 h. After the reaction was completed, the reaction solution was cooled to room temperature, extracted with water and dichloromethane, and the organic phase was concentrated under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography using a dichloromethane / petroleum ether (volume ratio 1:5) system to obtain 12.8 g of pure compound A-18 (yield 75%), HR-MS (ACPI-M+, m / z): 775.909.

[0052] (7) Preparation of Compound 29 The synthetic route of compound 29 is as follows:

[0053] Under nitrogen atmosphere, compound 25 (10 g, 17 mmol), compound 28 (8.2 g, 18.7 mmol), potassium carbonate (9.4 g, 68 mmol) and [1,1'-bis(diphenylphosphino)ferrocene] dichloropalladium dichloromethane complex (0.2 g, 0.2 mmol) were added to a 500 mL two-necked flask in sequence, and the solvent was 100 mL of tetrahydrofuran and 20 ml of water, and stirred at 70°C for 3 h. After the reaction was completed, the reaction solution was cooled to room temperature, extracted with water and dichloromethane, and the organic phase was concentrated under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography using a dichloromethane / petroleum ether (volume ratio 1:5) system to obtain 9.6 g of pure compound 29 (yield 70%), HR-MS (ACPI-M+, m / z): 807.755.

[0054] (8) Preparation of compound E-16 The synthetic route of compound E-16 is as follows:

[0055] Under nitrogen atmosphere, compound 29 (10 g, 12.4 mmol), compound 26 (5.7 g, 13.6 mmol), potassium carbonate (6.8 g, 49.6 mmol) and [1,1'-bis(diphenylphosphino)ferrocene] dichloropalladium dichloromethane complex (0.1 g, 0.1 mmol) were added to a 500 mL two-necked flask in sequence, and the solvent was 100 mL of tetrahydrofuran and 20 ml of water, and stirred at 70°C for 3 h. After the reaction was completed, the reaction solution was cooled to room temperature, extracted with water and dichloromethane, and the organic phase was concentrated under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography using a dichloromethane / petroleum ether (volume ratio 1:5) system to obtain 9.3 g of pure compound E-16 (yield 73%), HR-MS (ACPI-M+, m / z): 1022.188.

[0056] Application Example 1: Preparation of organic electroluminescent devices This application example provides an organic electroluminescent device, including an anode, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer and a cathode stacked in sequence on a substrate, and the device structure is: ITO / hole injection layer / hole transport layer / organic light-emitting layer / electron transport layer / electron injection layer / cathode, and the structural schematic diagram is shown in FIG. Figure 1 shown.

[0057] Among them, the anode is made of ITO material; the hole injection layer material is made of the following structural materials: ; The hole transport layer material is selected from the following compounds: The organic light-emitting layer is formed by co-doping a host material and a guest material, wherein the host material is a compound host, the guest material is a compound A-1, and the mass ratio of the host material to the guest material is 80:20; wherein the chemical structure of the compound Host is as follows: The electron transport layer material is selected from the compound with the following structure: The electron injection layer material is composed of LiF. The cathode material is metal Al.

[0058] The preparation of the organic electroluminescent device comprises the following steps: 1) Substrate cleaning: The glass substrate coated with the ITO transparent electrode was ultrasonically treated in a commercial cleaning agent, then rinsed in deionized water, ultrasonically degreased in a mixed solvent of acetone and ethanol (acetone and ethanol in a volume ratio of 1:1), baked in a clean environment until the moisture was completely removed, and then cleaned with ultraviolet light and ozone.

[0059] 2) Preparation of organic layer: The ITO transparent substrate was transferred to the evaporation equipment, and a 5 nm HIL layer, a 60 nm HTL layer, a 40 nm EML layer, a 40 nm ETL layer, a 0.5 nm EIL layer and a 100 nm aluminum layer were sequentially evaporated as the cathode.

[0060] Application Example 2: Preparation of organic electroluminescent devices An organic electroluminescent device was prepared by the same method as in Application Example 1, except that the guest material in the organic light-emitting layer was replaced by Compound A-4 prepared in Example 1 instead of Compound A-1.

[0061] Application Example 3: Preparation of organic electroluminescent devices An organic electroluminescent device was prepared by the same method as in Application Example 1, except that the guest material in the organic light-emitting layer was replaced by compound A-18 instead of compound A-1.

[0062] Application Example 4: Preparation of organic electroluminescent devices An organic electroluminescent device was prepared by the same method as in Application Example 1, except that the guest material in the organic light-emitting layer was replaced by compound B-4 instead of compound A-1.

[0063] Application Example 5: Preparation of organic electroluminescent devices An organic electroluminescent device was prepared by the same method as in Application Example 1, except that the guest material in the organic light-emitting layer was replaced by compound C-29 instead of compound A-1.

[0064] Comparative Example 1: Preparation of organic electroluminescent device An organic electroluminescent device was prepared by the same method as in Application Example 1. The guest material in the organic light-emitting layer was selected as R1. The structural formula of the compound R1 is shown below:

[0065] The prepared organic electroluminescent device was tested, wherein the voltage V J10 At a current density of 10 mA / cm 2 The external quantum efficiency EQE J60 At a current density of 60 mA / cm 2 The current efficiency CE is calculated under the following conditions: max is the maximum current efficiency of the device, external quantum efficiency EQE max is the maximum external quantum efficiency of the device. The test results are shown in Table 6: Table 6

[0066] From the performance of the above device embodiments, it can be seen that the device application examples can show higher efficiency than the comparative example 1 using the doping materials designed by the present invention. More importantly, the device results show that the doping materials A-1, A-4, A-18, B-4 and C-29 designed by the present invention show lower efficiency roll-off. The organic electroluminescent device prepared in application example 1 has the best test results. The EQE of application example 1 is 2.30 W at a current density of 60 mA / cm 2 The measured value EQE J60 With EQE max Compared with the above, the EQE of Comparative Example 1 is still around 85%. J60 With EQE max The ratio of is only 0.33, which means a very large efficiency roll-off, indicating that the compound prepared by the present invention has the characteristic of improving luminous efficiency. Therefore, the doping materials designed by the present invention all show a lower triplet energy level difference ΔE ST and higher photoluminescence quantum yield, which is better than Comparative Example 1.

[0067] The structure and combination of the donor unit in the molecule of the thermally activated delayed fluorescent luminescent material prepared by the present invention can effectively regulate the overlap of the electron cloud between the donor and the acceptor, significantly affect the energy level, band gap and triplet excited state energy level, and improve the singlet and triplet energy level difference; in addition, the bridging unit in the molecule forms a dihedral angle with the donor and acceptor units, which promotes and improves the molecular stacking and aggregated luminescence behavior. The thermally activated delayed fluorescent luminescent material prepared by the present invention has better thermal stability, higher photoluminescence quantum efficiency and smaller ΔEST and high reverse intersystem transition rate, and has broad application prospects in organic semiconductor devices, biology, and sensing.

[0068] As described above, although the present invention has been shown and described with reference to specific preferred application examples, it should not be interpreted as limiting the present invention itself. Various changes can be made to its form and details without departing from the spirit and scope of the present invention.

Claims

1. A thermally activated delayed fluorescence luminescent material based on a benzoxazole ring core, characterized in that: The thermally activated delayed fluorescent luminescent material is a compound represented by the general formula (I): ； Wherein, X is O, S, Se, NR or , R is selected from C1-C24 straight chain or branched alkyl, substituted C6-C30 aryl, C5-C30 heteroaryl; R1 and R2 are selected from substituted C6-C30 aryl, C5-C30 heteroaryl; L1 and L2 are single bonds or arylene groups; Y is CH or N; Ar1 and Ar2 are independently aromatic groups connected to L1 and L2 via a nitrogen atom, and at least one of them is a structure represented by the general formula (II): ； In the general formula (II), Ar3 and Ar4 are independently selected from a substituted or unsubstituted benzene ring, a naphthalene ring, a thiophene ring, a benzothiophene ring, a benzofuran, an anthracene ring, a phenanthrene ring, and a pyrene ring.

2. The thermally activated delayed fluorescent material according to claim 1, characterized in that: Ar3 and Ar4 are each independently one of the following formulae: ； Wherein, R3 represents a substituent on Ar3 and Ar4, n is selected from an integer of 0-4, representing 0-4 substituents represented by R3, m is selected from an integer of 0-2, representing 0-2 substituents represented by R3; R3 is independently selected from deuterium, halogen, cyano, C1-C10 alkyl, C1-C10 alkoxy, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C30 heteroaryl.

3. The thermally activated delayed fluorescent material according to claim 1, characterized in that: In the thermally activated delayed fluorescent luminescent material, and Each is independently one of the following: ； 。 4. The thermally activated delayed fluorescent material according to claim 1, characterized in that: The thermally activated delayed fluorescent luminescent material comprises the following compounds: ； ； ； ； ； ； ； ； ； 。 5. Use of the thermally activated delayed fluorescent material according to any one of claims 1 to 4 in the preparation of an organic electroluminescent device.

6. The use according to claim 5, characterized in that: The organic electroluminescent device comprises an anode, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer and a cathode which are sequentially stacked on a substrate; the organic light-emitting layer comprises a host material and a guest material, and the guest material comprises one or two of the thermally activated delayed fluorescent light-emitting materials described in any one of claims 1 to 4.

7. Use of the thermally activated delayed fluorescent luminescent material according to any one of claims 1 to 4 in the preparation of optical devices.

8. The method for preparing the thermally activated delayed fluorescent luminescent material according to claim 1, characterized in that: Step 1: prepare Ar1 and Ar2. The preparation reaction equations of Ar1 and Ar2 are: ； Step 2: using the prepared Ar1 and Ar2 to synthesize the thermally activated delayed fluorescent light-emitting material according to claim 1; (1) When L1 and L2 are single bonds, and Ar1 and Ar2 are the same, the preparation reaction equation of the thermally activated delayed fluorescent luminescent material is: ； (2) When L1 and L2 are single bonds and Ar1 and Ar2 are different, the preparation reaction equation is: ； (3) When L1 and L2 are the same arylene group, Ar5 represents an arylene group, and Ar1 and Ar2 are the same, the preparation reaction equation of the thermally activated delayed fluorescent luminescent material is: ； (4) When L1 and L2 are the same arylene group, Ar1 and Ar2 are different; or when L1 and L2 are different arylene groups, Ar5 and Ar6 represent arylene groups, and Ar1 and Ar2 are the same or different, the preparation reaction equation of the thermally activated delayed fluorescent luminescent material is: ； (5) When L1 is a single bond, L2 is an arylene group, Ar5 represents an arylene group, and Ar1 and Ar2 are the same or different, the preparation reaction equation of the thermally activated delayed fluorescent light-emitting material is: ； (6) When L1 is an arylene group, L2 is a single bond, Ar5 represents an arylene group, and Ar1 and Ar2 are the same or different, the preparation reaction equation is: 。

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