Synthesis and application of circularly polarized D-O-A type organic room-temperature electrophosphorescent material based on triptycene derivative group

Abstract

The invention relates to the field of circularly polarized electroluminescent materials, in particular to synthesis and application of a circularly polarized D-O-A type organic room-temperature electrophosphorescent material based on a triptycene derivative group. The triptycene derivative group is used as a chiral unit to be introduced into a donor-oxygen-receptor type structure; and designing and synthesizing the circularly polarized D-O-A type organic room-temperature electrophosphorescent material. On the other hand, the introduction of the triptycene derivative group endows the target molecule with a stable chiral environment, and on the other hand, the folded and twisted molecular structure can also inhibit molecular accumulation and high-concentration quenching and improve the device performance; the introduction of the D-O-A structure is beneficial to enhancing the spin-orbit coupling (SOC) and intersystem crossing (ISC) processes of molecules, so that an efficient organic room-temperature electrophosphorescence phenomenon is realized. According to the present invention, the circular polarization luminescence characteristic and the organic room temperature phosphorescence performance are completely combined, the new material with the circular polarization luminescence performance and the organic room temperature electrophosphorescence performance is developed, and the new development strategy is provided for the development of the circular polarization OLED luminescent material.

Description

Technical Field

[0001] The present invention relates to the technical field of circularly polarized electroluminescent materials, and specifically relates to the synthesis and application of a circularly polarized D-O-A type organic room temperature electroluminescent material based on a triptycene derivative group. Background Art

[0002] Organic light-emitting diodes (OLEDs) have been widely used in the modern display and lighting industries due to their low driving voltage, high display quality, fast response speed, wide viewing angle, good low-temperature characteristics, low energy consumption, flexibility, and ultrathinness. Circularly polarized luminescent materials have attracted extensive attention because they can directly emit circularly polarized light and have shown great promise in the field of 3D displays. Currently, the research on circularly polarized luminescent materials mainly focuses on circularly polarized fluorescent materials, circularly polarized phosphorescent materials, and circularly polarized TADF materials. However, existing circularly polarized luminescent materials generally suffer from problems such as low device efficiency and low dissymmetry factor, which seriously restrict their further development. Therefore, the development of new circularly polarized luminescent materials is extremely urgent.

[0003] Organic room temperature phosphorescent materials have advantages such as low cost, long lifespan, easy synthesis, and good biocompatibility, and currently show good development prospects in OLEDs. In our previous research work, we found that the donor-oxygen-acceptor (D-O-A) structure based on acridine derivatives has unique advantages in realizing organic room temperature electroluminescence. Therefore, in this research work, a triptycene derivative group with circularly polarized properties is combined with the D-O-A structure to develop a circularly polarized D-O-A type organic room temperature electroluminescent material based on a triptycene derivative group, providing a new approach for the development of future circularly polarized OLED luminescent materials. Summary of the Invention

[0004] The purpose of the present invention is to provide a D-O-A type organic room temperature electroluminescent material based on a triptycene derivative group, its synthesis method and application. By introducing a triptycene derivative unit into the target molecule, the target molecule has chiral properties; the introduction of oxygen atoms in the donor-O-electron acceptor (D-O-A) type structure can enhance the SOC and intersystem crossing processes, enabling the target molecule to have room temperature phosphorescence properties. The two work together to achieve both circularly polarized luminescence properties and organic room temperature electroluminescence properties. The present invention first proposes introducing a triptycene derivative unit as a chiral source into the donor-O-electron acceptor (D-O-A) type structure to design and synthesize a circularly polarized D-O-A type organic room temperature electroluminescent material.

[0005] To achieve the above technical objectives and reach the above technical effects, the present invention is realized through the following technical solutions:

[0006] A circularly polarized D-O-A type organic room temperature electrophosphorescent material based on a triptycene derivative group, and its structural formula includes but is not limited to the following structures:

[0007]

[0008] On the other hand, the present invention provides a synthesis method of the above-mentioned circularly polarized D-O-A type organic room temperature electrophosphorescent material, including the following steps:

[0009] S1: Under the catalysis of tris(dibenzylideneacetone)dipalladium and tributylphosphine tetrafluoroborate, using sodium tert-butoxide as the base, bromobenzene and compound 1 are subjected to a coupling reaction in toluene solvent at 120 °C to generate compound 2, which is purified by a chromatography column to provide a basic structure for subsequent reactions;

[0010] S2: Using N-bromosuccinimide as the bromination reagent, compound 2 is subjected to a selective bromination reaction in an ice-water bath and DMF solvent to introduce an active bromine site, and after extraction and purification by a chromatography column, compound 3 is obtained, providing a precise reaction site for subsequent borylation reactions,

[0011] S3: Using bis(pinacolato)diboron as the boron source, potassium acetate as the base, and [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium as the catalyst, compound 3 is subjected to a borylation reaction at 75 °C to generate a borate intermediate, and after extraction and purification by a chromatography column, reaction intermediate compound 4 for the Suzuki coupling reaction is provided;

[0012] S4: Compound 4, cellulose, and tetrahydrofuran are mixed, 30% aqueous hydrogen peroxide solution is added dropwise, and the mixture is stirred at room temperature for 5 minutes. After the reaction is complete, compound 5 is obtained through extraction, drying, and purification by chromatography column separation;

[0013] S5: Using potassium carbonate as the base, compound 5 is subjected to a pre-cyclization reaction at 140 °C, and then 2-(4-fluorophenyl)-4,6-diphenyl-1,3,5-triazine is added, and the final cyclization reaction is completed at 160 °C. After extraction and purification by a chromatography column, the target organic electrophosphorescent material compound 6 is obtained.

[0014] Further, the step S1 includes the following sub-steps:

[0015] S1.1: Under a nitrogen atmosphere, tris(dibenzylideneacetone)dipalladium (0.15 g, 0.16 mmol), tributylphosphine tetrafluoroborate (0.24 g, 0.82 mmol), and sodium tert-butoxide (0.99 g, 10.25 mmol) are added to a three-necked flask.

[0016] S1.2: Add bromobenzene (0.81 g, 5.13 mmol) and a toluene solution (22 mL) of compound 1 (1.06 g, 2.05 mmol) dissolved in batches.

[0017] S1.3: Reflux and stir overnight in an oil bath at 120 °C, monitor the completion of the reaction by thin-layer chromatography (TLC), and cool to room temperature.

[0018] S1.4: Rotavaporize the solvent, separate and purify by column chromatography to obtain the product compound 2;

[0019] Furthermore, the step S2 includes the following sub-steps:

[0020] S2.1: Under a nitrogen atmosphere, dissolve compound 2 (0.10 g, 0.15 mmol) in ultra-dry N,N-dimethylformamide (DMF, 5 mL), and stir in an ice-water bath.

[0021] S2.2: Dissolve N-bromosuccinimide (0.017 g, 0.14 mmol) in ultra-dry DMF (5 mL), and slowly add it dropwise to the DMF solution of compound 2. Stir at 0 °C to room temperature for 2 hours, and monitor the completion of the reaction by TLC.

[0022] S2.3: Add distilled water (20 mL), extract with dichloromethane (15 mL), separate the layers, collect the organic layer, and wash and extract with water repeatedly 3 times.

[0023] S2.4: Dry the organic phase with anhydrous sodium sulfate, rotavaporize the solvent, separate and purify by column chromatography to obtain compound 3.

[0024] Furthermore, the step S3 includes the following sub-steps:

[0025] S3.1: Under a nitrogen atmosphere, add compound 3 (0.40 g, 0.53 mmol), bis(pinacolato)diboron (0.48 g, 1.87 mmol), potassium acetate (0.34 mg, 3.45 mmol), [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium (0.0039 mg, 0.054 mmol) and DMF (36 mL) to a three-necked flask, stir overnight at 75 °C, and cool to room temperature.

[0026] S3.2: Add distilled water (100 mL), extract with ethyl acetate (75 mL), separate the layers, collect the organic layer, and wash and extract with water repeatedly 3 times.

[0027] S3.3: Dry the organic phase with anhydrous sodium sulfate, rotavaporize the solvent, separate and purify by column chromatography to obtain compound 4.

[0028] Furthermore, the step S4 includes the following sub-steps:

[0029] S4.1: Add compound 4 (0.20 g), cellulose (0.02 g), and tetrahydrofuran (4 mL) into a three-necked flask, slowly dropwise add 30% aqueous hydrogen peroxide solution (1 mL), and stir at room temperature for 5 minutes.

[0030] S4.2: Monitor the completion of the reaction by TLC, extract with ethyl acetate (10 mL), and collect the organic phase after liquid separation.

[0031] S4.3: Dry the organic phase with anhydrous sodium sulfate, rotary evaporate the solvent, and separate and purify by a chromatography column to obtain compound 5.

[0032] Furthermore, the step S5 includes the following sub-steps:

[0033] S5.1: Under a nitrogen atmosphere, add compound 5 (0.10 g, 0.15 mmol), potassium carbonate (0.10 g, 0.73 mmol) into a three-necked flask, add N-methylpyrrolidone (1 mL) and toluene (1 mL), and reflux at 140 °C for 2 hours.

[0034] S5.2: Cool to room temperature, dissolve 2-(4-fluorophenyl)-4,6-diphenyl-1,3,5-triazine (0.048 g, 0.15 mmol) in N-methylpyrrolidone (1 mL), add it to the reaction system, and reflux at 160 °C overnight.

[0035] S5.3: Monitor the completion of the reaction by TLC, cool to room temperature, add distilled water (30 mL), extract with ethyl acetate (20 mL), collect the organic layer after liquid separation, and wash and extract repeatedly 3 times.

[0036] S5.4: Dry the organic phase with anhydrous sodium sulfate, rotary evaporate the solvent, and separate and purify by a chromatography column to obtain compound TpAc-O-TRZ (0.06 g, 41.4%).

[0037] Furthermore, the synthesis general formula of the circularly polarized D-O-A type organic room temperature electrophosphorescent material is as follows:

[0038]

[0039] Another object of the present invention is to provide the application of the above-mentioned circularly polarized D-O-A type organic room temperature electrophosphorescent material in an organic electroluminescent device.

[0040] Advantages of the present invention:

[0041] The rigid propeller structure of the chiral triptycene derivative significantly inhibits intramolecular vibration and rotation through steric hindrance effects, reducing the probability of non-radiative transitions. Its C3 symmetry induces π-π stacking to form a helical supramolecular arrangement, creating a stable chiral microenvironment that results in a highly directional distribution of the electronic transition dipole moments during the luminescence process, thereby enhancing the asymmetry factor (g-factor) of circularly polarized luminescence. The turn-on voltage (V on ) of the OLED device of the present invention is only 3.6 V, significantly lower than the 4 - 6 V of traditional OLED devices. This breakthrough benefits from the intramolecular charge transfer effect of the D-O-A unit. The D-O-A structure significantly reduces the energy level difference between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the material through charge transfer between the electron donor (Donor) and the electron acceptor (Acceptor), thereby reducing the excitation energy requirement for electrons. This property enables the device to achieve efficient luminescence at a lower voltage. In addition, the introduction of the rigid triptycene structure further suppresses non-radiative energy loss and improves the utilization efficiency of electrons. The low driving voltage not only reduces the energy consumption of the device but also extends its service life, providing important technical support for the development of energy-saving and efficient OLED devices.

[0042] The material of the present invention achieves efficient phosphorescence emission at room temperature. Thanks to the rigid structure of the chiral triptycene derivative unit, intramolecular vibration and rotation are effectively inhibited through steric hindrance effects, reducing the energy loss caused by non-radiative transitions, thereby improving the phosphorescence emission efficiency. At the same time, the D-O-A unit enhances the spin-orbit coupling (SOC) effect through the intramolecular charge transfer (ICT) effect, promoting the intersystem crossing (ISC) process from singlet excitons to triplet excitons, and significantly increasing the yield of triplet excitons. In addition, by introducing the chiral triptycene derivative structure, the device achieves an extremely high photoelectric conversion efficiency in the process of converting electron-hole pairs into photons.

[0043] The maximum brightness (L max ) of the OLED device of the present invention reaches 7651 cd m -2 , the electroluminescence peak wavelength is 498 nm, and the chromaticity coordinates (CIE) are (0.22, 0.41), indicating that the device has high brightness and color purity in the blue-green spectral range. The steric confinement effect of the chiral triptycene derivative and the excited state of the D-O-A structure are synergistically regulated to precisely control the electroluminescence peak position of the material in the 498 nm blue-green light region, and the color purity CIE (0.22, 0.41) reaches 95% of the NTSC standard color gamut. The rigid molecular framework effectively inhibits the structural relaxation during device operation. Through the directional confinement effect of the helical supramolecular arrangement on the exciton migration path, the material of the present invention has excellent visual effects in display and lighting applications, meeting the requirements of modern display technology for high resolution and high color reproducibility.

[0044] The circularly polarized D-O-A type organic room temperature electrophosphorescent material of the present invention achieves good circularly polarized luminescence performance, thanks to the introduction of the chiral triptycene derivative group and its helical supramolecular arrangement characteristics. The C3 symmetry of the chiral triptycene derivative induces the material molecules to form a chiral configuration, generating circularly polarized light during the luminescence process. The circularly polarized luminescence characteristics of the material of the present invention, combined with its efficient room temperature phosphorescence performance, open up a new direction for the development of circularly polarized OLED luminescent materials.

[0045] Of course, it is not necessary for any product implementing the present invention to simultaneously achieve all the above-mentioned advantages. Brief Description of the Drawings

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0047] Figure 1 is the circular dichroism spectrum of (S / R)-TpAc-O-TRZ in toluene solution;

[0048] Figure 2 is the circularly polarized photoluminescence spectrum of (S / R)-TpAc-O-TRZ in toluene solution;

[0049] Figure 3 is the circularly polarized luminescence dissymmetry factor spectrum of (S / R)-TpAc-O-TRZ in toluene solution; g CPL =-4.95×10 -4 ,2.95×10 -4 ;

[0050] Figure 4 is the room temperature electroluminescence spectrum and phosphorescence spectrum of TpAc-O-TRZ in the pure film.

[0051] Figure 5 is the electroluminescence spectrum of the OLED device described in Example 3;

[0052] Figure 6 is the relationship diagram between the external quantum efficiency and the brightness of the OLED device described in Example 3;

[0053] Figure 7 is the circularly polarized electroluminescence spectrum of the OLED device described in Example 3;

[0054] Figure 8 is the circularly polarized luminescence dissymmetry factor spectrum of the OLED device described in Example 3; gCPEL = -7.33×10 -4 ,8.17×10 -4 。 Detailed implementation manners

[0055] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0056] Embodiment 1

[0057] A circularly polarized D-O-A type organic room temperature electrophosphorescent material based on a triptycene derivative group described in this embodiment includes, but is not limited to, the following structure:

[0058]

[0059] In this embodiment, a synthesis method of the above-mentioned circularly polarized D-O-A type organic room temperature electrophosphorescent material is proposed, including the following steps:

[0060] S1: Take tris(dibenzylideneacetone)dipalladium(0) (0.15 g, 0.16 mmol), tributylphosphine tetrafluoroborate (0.24 g, 0.82 mmol), and sodium tert-butoxide (0.99 g, 10.25 mmol) in a three-necked flask, and make it in a nitrogen atmosphere. Add bromobenzene (0.81 g, 5.13 mmol) into the three-necked flask. Dissolve 9 compound 1 (1.06 g, 2.05 mmol) in 22 mL of toluene in batches and then introduce it into the system. Heat it in an oil bath at 120 °C and reflux and stir overnight. After monitoring the reaction to be complete by thin layer chromatography, cool it to room temperature, then pour the system into a single-necked flask and spin-dry it. Separate and purify the product by a chromatography column to obtain the product (1.23 g, 89.8%), and its synthesis formula is as follows:

[0061]

[0062] S2: Take compound 2 (0.10 g, 0.15 mmol) in a three-necked flask, place it under a nitrogen atmosphere, add ultra-dry N,N-dimethylformamide (5 mL) to dissolve it, and stir in an ice-water bath. Take N-bromosuccinimide (0.017 g, 0.14 mmol) in a conical flask, add ultra-dry N,N-dimethylformamide (5 mL) to dissolve it, add it to a constant-pressure dropping funnel, and slowly drop it into the DMF solution of compound 2, and stir at 0 °C to room temperature for 2 h. After the reaction is completed using thin-layer chromatography, transfer the reaction system to a beaker, add 20 mL of distilled water to mix, add 15 mL of dichloromethane for extraction, separate with a separating funnel, collect the organic layer, and wash and extract it repeatedly with water 3 times. The organic phase is dried over anhydrous sodium sulfate, filtered and then rotary evaporated. After separation and purification using a chromatography column, compound 3 (0.11 g, 98.2%) is obtained. Its synthesis formula is as follows:

[0063]

[0064] S3: Add compound 3 (0.40 g, 0.53 mmol), bis(pinacolato)diboron (0.48 g, 1.87 mmol), potassium acetate (0.34 mg, 3.45 mmol), [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium (0.0039 mg, 0.054 mmol) and N,N-dimethylformamide (36 mL) into a three-necked flask in sequence, place it under a nitrogen atmosphere, and stir at 75 °C overnight. After the reaction is completed, wait for the reaction system to cool to room temperature, transfer it to a beaker, add 100 mL of distilled water to mix, extract with 75 mL of ethyl acetate, separate with a separating funnel, collect the organic layer, and wash and extract it repeatedly with water 3 times. The organic phase is dried over anhydrous sodium sulfate, filtered and then rotary evaporated. Separation and purification using a chromatography column gives compound 4 (0.24 g, 57.1%). Its synthesis formula is as follows:

[0065]

[0066] S4: Take compound 4 (0.20 g), cellulose (0.02 g), and tetrahydrofuran (4 mL) in a three-necked flask, slowly add 30% aqueous hydrogen peroxide solution (1 mL) dropwise thereto, and stir at room temperature for 5 minutes. After monitoring the reaction to completion using thin-layer chromatography, transfer the reaction system to a beaker, extract with 10 mL of ethyl acetate, separate with a separating funnel, collect the organic phase, dry over anhydrous sodium sulfate, filter and then rotary evaporate. Analysis and purification using a chromatography column gives compound 5 (0.10 g, 58.8%). Its synthesis formula is as follows:

[0067]

[0068] S5: In a three-necked flask, place compound 5 (0.10 g, 0.15 mmol) and potassium carbonate (0.10 g, 0.73 mmol). Add N-methylpyrrolidone (1 mL), evacuate and replace the air to create a nitrogen atmosphere, then add toluene (1 mL). Reflux at 140 °C for 2 h. Cool the reaction system to room temperature. Take 2-(4-fluorophenyl)-4,6-diphenyl-1,3,5-triazine (0.048 g, 0.15 mmol), dissolve it in N-methylpyrrolidone (1 mL), evacuate and replace the air, then inject it into the reaction system. Reflux at 160 °C overnight. After monitoring the completion of the reaction by thin-layer chromatography and cooling the reaction system to room temperature, transfer it to a beaker, add 30 mL of distilled water to mix, extract with 20 mL of ethyl acetate, separate the layers using a separating funnel, and collect the organic layer. Wash and extract with water three times repeatedly. Dry the organic phase over anhydrous sodium sulfate, filter, and evaporate to dryness. Separate and purify by column chromatography to obtain compound TpAc-O-TRZ (0.06 g, 41.4%), and its synthesis formula is as follows:

[0069]

[0070] In this example, the general synthesis formula of the circularly polarized D-O-A type organic room temperature electrophosphorescent material is as follows:

[0071]

[0072] Example 2

[0073] Perform 1H NMR detection on the product obtained in Example 1:

[0074] 1 H NMR (400 MHz, DMSO) δ 8.70 (t, J = 8.2 Hz, 1H), 7.80–7.57 (m, 2H), 7.49 (s, 1H), 7.40 (d, J = 7.4 Hz, 1H), 7.34 (s, 1H), 7.35–7.22 (m, 1H), 7.09 (d, J = 8.8 Hz, 1H), 6.87 (dd, J = 34.0, 5.8 Hz, 1H), 6.27 (d, J = 15.8 Hz, 1H), 6.15 (d, J = 8.8 Hz, 1H), 6.04 (d, J = 8.1 Hz, 1H), 5.28 (d, J = 6.0 Hz, 1H), 1.54 (dd, J = 10.8, 5.2 Hz, 2H).

[0075] It can be seen that the chemical shift (δ value) ranges from 1.54 to 8.70 ppm, clearly reflecting the distribution of aromatic and aliphatic hydrogens in the compound; the aromatic hydrogen signals are concentrated at δ 6.0–8.7 ppm, indicating the successful introduction of the aromatic ring structure and a complex substitution pattern; δ 8.70 (t, J = 8.2 Hz, 1H) and δ 7.80–7.57 (m, 2H) show multiple couplings of hydrogen atoms on the aromatic ring, which is consistent with the goal of constructing the core aromatic skeleton through palladium-catalyzed coupling reactions in the technical solution.

[0076] The aliphatic hydrogen signal δ 1.54 (dd, J = 10.8, 5.2 Hz, 2H) indicates the presence of an aliphatic chain or cyclic structure in the compound, and its multiple splitting pattern further verifies the complexity of the substituents. The 1H NMR spectrum also reveals the interaction between hydrogen atoms through the splitting pattern and coupling constant (J value) of aromatic hydrogens; δ 6.87 (dd, J = 34.0, 5.8 Hz, 1H) and δ 6.27 (d, J = 15.8 Hz, 1H) show the spatial position relationship of hydrogen atoms on the aromatic ring, verifying the successful completion of the selective bromination reaction and borylation reaction.

[0077] In addition, no obvious impurity peaks appear in the 1H NMR spectrum, indicating that the compound has a high purity after purification by a chromatography column. The signal distribution of aromatic and aliphatic hydrogens also indicates that the compound has a good conjugated structure and electron cloud distribution, which provides an important basis for its application in organic electroluminescent devices, verifies the effectiveness of each step of the preparation method of the present invention, and lays a solid experimental foundation for subsequent industrial production and application.

[0078] Example 3

[0079] The organic electroluminescent device OLED as described in this example is prepared from the circularly polarized D-O-A type organic room temperature electrophosphorescent material obtained in Example 1, and the performance parameters are shown in Table 1;

[0080] Table 1

[0081]

[0082] From the experimental data, the external quantum efficiency (EQE) of the present invention reaches 20.19%, indicating that the device achieves an extremely high photoelectric conversion efficiency in the process of converting electron-hole pairs into photons. The rigid structure of the triptycene derivative of the present invention significantly inhibits intramolecular vibration and rotation through steric hindrance effects, reducing the probability of non-radiative transitions; the D-O-A unit enhances the spin-orbit coupling effect through the intramolecular charge transfer effect, promoting the intersystem crossing process, thereby increasing the triplet exciton yield; the C3 symmetry of chiral triptycene induces π-π stacking to form a helical supramolecular arrangement, stabilizing excitons and enhancing the luminescence efficiency. These cooperative mechanisms work together to achieve efficient room temperature phosphorescence emission.

[0083] The turn-on voltage V of the device on is only 3.6V, significantly lower than that of traditional OLED devices (usually 4 - 6V), indicating that the device can achieve efficient light emission at low voltages. The intramolecular charge transfer effect of the D-O-A unit significantly reduces the energy level difference between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), reducing the energy requirement for electron excitation.

[0084] The maximum brightness (L max ) of the device of the present invention reaches 7651 cd / m² -2 , the peak wavelength of electroluminescence is 498 nm, and the chromaticity coordinates (CIE) are (0.22, 0.41), indicating that the light emitted by the device is close to blue-green and has high brightness and color purity.

[0085] By introducing a triptycene derivative group into the D-O-A type organic room temperature electrophosphorescent material, the present invention combines the intramolecular charge transfer (ICT) effect and the spatial confinement effect of the chiral structure, achieving significant breakthroughs in high efficiency, low turn-on voltage, high brightness, high-quality light emission, and circularly polarized light emission performance.

[0086] In summary, the present invention synthesizes a new type of D-O-A type circularly polarized organic room temperature phosphorescent small molecule, which combines a chiral triptycene derivative unit and a D-O-A unit, and is expected to simultaneously achieve good circularly polarized light emission performance and organic room temperature phosphorescent performance, providing a new approach for the development of circularly polarized OLED luminescent materials.

[0087] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art in the relevant technical field can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A circularly polarized DOA type organic room temperature electrophosphorescent material based on a triptycene derivative group, characterized in that: The triptycene derivative unit is introduced as a chiral source into an electron donor-O-electron acceptor type structure, and its structural formula includes but is not limited to the following structure:

2. The method for synthesizing the circularly polarized DOA type organic room temperature electrophosphorescent material according to claim 1, characterized in that: The following steps are involved: S1: Under the catalysis of tri(dibenzylideneacetone) dipalladium and tributylphosphine tetrafluoroborate, with sodium tert-butoxide as a base, bromobenzene and compound 1 are subjected to coupling reaction in toluene solvent at 120°C, and purified by chromatography to obtain compound 2; S2: Compound 2 was selectively brominated in an ice-water bath and DMF solvent using N-bromosuccinimide as the bromination reagent to introduce active bromine sites. Compound 3 was obtained by extraction and column purification to provide precise reaction sites for subsequent borylation reactions. S3: Using bis-pinacol borate as a boron source, potassium acetate as a base, and [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride as a catalyst, compound 3 is subjected to borylation reaction at 75°C to generate a borate ester intermediate, which is then extracted and purified by chromatography to provide a reaction intermediate compound 4 for the Suzuki coupling reaction; S4: Compound 4, cellulose and tetrahydrofuran were mixed, 30% aqueous hydrogen peroxide solution was added dropwise, and the mixture was stirred at room temperature for 5 minutes. After the reaction was complete, compound 5 was obtained by extraction, drying and separation and purification by chromatography column; S5: Using potassium carbonate as a base, compound 5 was subjected to a pre-cyclization reaction at 140°C, and then 2-(4-fluorophenyl)-4,6-diphenyl-1,3,5-triazine was added to complete the final cyclization reaction at 160°C. After extraction and purification by chromatography, compound 6 was obtained, i.e., the target product, DOA-type room-temperature electrophosphorescent material.

3. The synthesis method according to claim 2, characterized in that: The step S1 comprises the following sub-steps: S1.1: Under a nitrogen atmosphere, add tri(dibenzylideneacetone)dipalladium, tributylphosphine tetrafluoroborate and sodium tert-butoxide into a three-necked flask; S1.2: adding bromobenzene and the toluene solution of compound 1 dissolved in batches; S1.3: Reflux and stir in an oil bath at 120°C overnight, monitor the reaction completion by TLC, and cool to room temperature; S1.4: The solvent was dried by spin drying, and the product, compound 2, was obtained by separation and purification using a chromatography column.

4. The synthesis method according to claim 2, characterized in that: The step S2 comprises the following sub-steps: S2.1: Under nitrogen atmosphere, dissolve compound 2 in ultra-dry N,N-dimethylformamide and stir in an ice-water bath; S2.2: Dissolve N-bromosuccinimide in ultra-dry DMF, and slowly add dropwise to the DMF solution of compound 2; stir at 0°C to room temperature for 2 hours, and monitor the completion of the reaction by TLC; S2.3: Add distilled water, extract with dichloromethane, collect the organic layer after separation, and wash and extract repeatedly with water 3 times; S2.4: The organic phase was dried over anhydrous sodium sulfate, the solvent was spin-dried, and the mixture was separated and purified using a chromatography column to obtain compound 3.

5. The synthesis method according to claim 2, characterized in that: The step S3 comprises the following sub-steps: S3.1: Under nitrogen atmosphere, compound 3, bis(pinacol borate), potassium acetate, [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride and DMF were added into a three-necked flask, stirred at 75° C. overnight, and cooled to room temperature; S3.2: Add distilled water, extract with ethyl acetate, collect the organic layer after separation, and wash the extract with water repeatedly for 3 times; S3.3: The organic phase was dried over anhydrous sodium sulfate, the solvent was spin-dried, and the mixture was separated and purified using a chromatography column to obtain compound 4.

6. The synthesis method according to claim 2, characterized in that: The step S4 comprises the following sub-steps: S4.1: Add compound 4, cellulose and tetrahydrofuran into a three-necked flask, slowly add 30% hydrogen peroxide aqueous solution dropwise, and stir at room temperature for 5 minutes; S4.2: Monitor the reaction completion by TLC, extract with ethyl acetate, separate and collect the organic phase; S4.3: The organic phase was dried over anhydrous sodium sulfate, the solvent was spin-dried, and the mixture was separated and purified using a chromatography column to obtain compound 5.

7. The synthesis method according to claim 2, characterized in that: The step S5 comprises the following sub-steps: S5.1: Under nitrogen atmosphere, compound 5 and potassium carbonate were added into a three-necked flask, and N-methylpyrrolidone and toluene were added, and refluxed at 140°C for 2 hours; S5.2: Cool to room temperature, dissolve 2-(4-fluorophenyl)-4,6-diphenyl-1,3,5-triazine in N-methylpyrrolidone, add to the reaction system, and reflux at 160°C overnight; S5.3: Monitor the reaction by TLC, cool to room temperature, add distilled water, extract with ethyl acetate, collect the organic layer after separation, and wash the extract with water for 3 times; S5.4: The organic phase is dried over anhydrous sodium sulfate, the solvent is dried by spin drying, and the mixture is separated and purified using a chromatography column to obtain the target compound TpAc-O-TRZ.

8. The synthesis method according to claim 2, characterized in that: The general synthesis formula of the circularly polarized DOA type organic room temperature electrophosphorescent material is as follows:

9. Use of the circularly polarized DOA type organic room temperature electrophosphorescent material as claimed in claim 1 in an organic electroluminescent device.

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