A dual-emission thermally activated delayed fluorescence material, and a preparation method and application thereof

Abstract

The application provides a kind of double emission thermally activated delayed fluorescence material and its preparation method and application.The double emission thermally activated delayed fluorescence material forms D-A skeleton structure by donor and acceptor, and the excitation state energy level of the material is regulated by regulating the sulfur atom connection site of donor and acceptor.The double emission thermally activated delayed fluorescence material is prepared by the preparation method, which comprises: mixing acceptor precursor, donor, potassium carbonate and injecting into solvent under argon atmosphere, stirring reaction;The solvent includes any one of tetrahydrofuran, N, N-dimethylformamide.The double emission thermally activated delayed fluorescence material is suitable for anti-fake field, information encryption field.The double emission thermally activated delayed fluorescence material provided by the application can reach 58.6 μs and 3.4 ms respectively, the preparation method is simple, has strong repeatability and high yield, inhibits non-radiative transition through hydrogen bond after film formation, prolongs the lifetime of triplet exciton, and has large-scale application prospect in multi-dimensional anti-fake field.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic light-emitting materials, and particularly relates to a dual-emission thermally activated delayed fluorescence material and a preparation method and application thereof. BACKGROUND

[0002] Thermally activated delayed fluorescence material, namely TADF material, is the third generation of pure organic structure delayed fluorescence material developed after fluorescent material and noble metal phosphorescent material. It breaks through the limit of the exciton utilization rate of traditional fluorescent material and realizes 100% exciton utilization rate, thereby greatly improving the quantum efficiency of OLED. The characteristic of TADF material lies in that the energy difference between the first singlet excited state S1 and the first triplet excited state T1 is small, so that T1 can be converted into S1 through the inverse intersystem crossing (RISC) process with the aid of heat and radiate light. Since the RISC process is slower than the radiation process of S1, the generated fluorescence is called delayed fluorescence. Its typical characteristics are small singlet-triplet energy gap and temperature positive dependence.

[0003] Most of the traditional TADF molecules only exhibit single emission characteristics, which limits their in-depth application in the fields of multi-color light emission and multi-functional fluorescent probes. Therefore, developing TADF molecules with dual emission characteristics has become a hot spot of current research.

[0004] Currently, the main design strategy for dual-emitting TADF molecules is to regulate the multiple conformations of the molecules. Wang et al. designed and synthesized compound 2-(9,9-dimethylacridin-10(9H)-yl)-3-phenylthiophene-5,5,10,10-tetraoxide (DMAC-PTR), due to the existence of a nearly planar conformation and an almost orthogonal conformation (82°) caused by a large steric hindrance, the conversion of this dual conformation is the key to realize dual emission (Wang K. et al. Adv. Mater. 2017, 29, 1701476). Zhu et al. developed 1,2-bis(4-methylphenyl)ethane-1,2-dione (DMBZ) and 1,2-bis(4-tert-butylphenyl)ethane-1,2-dione (DBBZ), which showed conformation-dependent luminescence on the basis of three conformational isomers over-torsion, torsion and planar (Zhu C. et al. J. Am. Chem. Soc. 2023, 145, 16748-16759). However, the chemical structures that achieve these functions are often complex and difficult to control accurately, which greatly limits their widespread and reliability in practical applications. Therefore, subsequent studies have focused on regulating the energy levels of different donor-acceptor charge transfer excited states within the molecule, reducing the energy gap (ΔEST) between S1 and T1, thereby facilitating the occurrence of RISC process and further regulating the characteristics of dual emission. Hua et al. prepared an orange-red TADF emitter with a three-dimensional structure by modifying the TNP unit with a tertiary butyl-modified naphthalene phenacyl imine-dimethyl acridine TADF unit, which has an SOC value of 0.862 cm -1 , which is an excellent strategy for designing high-performance TADF emitters by regulating the excited state (Hua L. et al. Nat. Commun. 2022, 13, 7828). However, the complex synthesis process limits the depth of popularization.

[0005] Therefore, for TADF materials with dual emission characteristics, how to achieve precise regulation of the structure of dual-emitting TADF materials under the premise of simplifying the preparation steps is a technical problem that needs to be overcome in the field.

[0006] In view of this, the present application is proposed. SUMMARY

[0007] The purpose of the present application is to provide a dual-emitting thermally activated delayed fluorescence material, a preparation method thereof and an application thereof, to solve the above problems.

[0008] To achieve the above purpose, the present application adopts the following technical solutions:

[0009] A dual-emission thermally activated delayed fluorescence material is formed by a donor and an acceptor to form a D-A skeleton structure, and the excitation state energy level of the material is regulated by regulating the sulfur atom connection site of the donor and the acceptor. Through the regulation of the excitation state energy level of the material, the regulation of the TADF property of the material molecule is further realized.

[0010] Optionally, the structural formula of the donor comprises

[0011] wherein R is any one of hydrogen (-H), methyl (-CH3), and tert-butyl (-C(CH3)3); and R at different sites is the same or different.

[0012] R at different sites is the same or different.

[0013] Preferably, the donor comprises 2,6-dimethylbenzenethiol and 1,2-benzenedithiol.

[0014] Optionally, the acceptor comprises any one or more of 2,1,3-benzothiadiazole, 1,3-dioxoisoindole-2-carbonitrile, and acenaphtho[1,2-b]quinoxaline-9,10-dicarbonitrile.

[0015] The structural formula of the acceptor comprises:

[0016]

[0017] wherein Z is sulfur (S) or selenium (Se);

[0018] T is any one of a cyano group (-CN), a ketone group (-CO), and an aromatic ring group (-Ar); and T at different sites is the same or different.

[0019] Preferably, the sulfur atom connection site of the donor and the acceptor comprises any one or more of S1, S2, S3, and S4.

[0020] Optionally, the structural formula of the fluorescent material comprises any one of the following structural formulas:

[0021]

[0022]

[0023] wherein R is any one of hydrogen (-H), methyl (-CH3), and tert-butyl (-C(CH3)3); and R at different sites is the same or different.

[0024] Z is sulfur (S) or selenium (Se);

[0025] T is any one of a cyano group (-CN), a ketone group (-CO), and an aromatic ring group (-Ar); and T at different sites is the same or different.

[0026] Optionally, the fluorescent material has any one of the following structural formulas:

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] Preferably, the sulfur atom connection sites of the donor and the acceptor are S2 and / or S3.

[0034] The present application provides a preparation method of the double-emission thermally activated delayed fluorescent material, the method comprising: mixing the acceptor precursor, the donor, potassium carbonate, and injecting into a solvent under an argon atmosphere, stirring the reaction, to obtain the double-emission thermally activated delayed fluorescent material.

[0035] The solvent comprises any one of tetrahydrofuran, N,N-dimethylformamide.

[0036] The stirring reaction is carried out at room temperature, and the stirring time is 12-14 h.

[0037] Optionally, the method comprises:

[0038] a. adding 4,7-difluoro-benzothiadiazole, 2,6-dimethylbenzenethiol, potassium carbonate solid into a reaction container, injecting tetrahydrofuran under an argon atmosphere, stirring the mixture at room temperature for 12 h to obtain compound 4,7-di(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole, which has the following structural formula: Preferably, the molar mass ratio of the 4,7-difluoro-benzothiadiazole, 2,6-dimethylbenzenethiol, and potassium carbonate solid is 1.8-2.2:4.1-4.2:18-22.

[0039] Further preferably, after stirring at room temperature for 12 h, the filtrate is collected by cooling and filtering, the reaction solvent is removed by rotary evaporation, and then the compound 4,7-di(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole is obtained by column chromatography separation and purification using petroleum ether / dichloromethane as an eluent.

[0040] b. In a reaction vessel, 5,6-difluoro-benzothiadiazole, 1,2-benzenedithiol, potassium carbonate are added under argon atmosphere, and N,N-dimethylformamide is injected. The mixture is stirred at room temperature for 12 h to obtain compound thianthrene[2,3-c][1,2,5]-thiadiazole, having the structural formula Preferably, the molar mass ratio of 5,6-difluoro-benzothiadiazole, 1,2-benzenedithiol, potassium carbonate is 1.8-2.2: 1.8-2.2: 18-22.

[0041] c. In a reaction vessel, 5,6-difluoro-benzothiadiazole, 2,6-dimethylbenzenethiol, potassium carbonate are added under argon atmosphere, and tetrahydrofuran is injected. The mixture is stirred at room temperature for 12 h to obtain compound 5,6-bis(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole, having the structural formula Preferably, the molar mass ratio of 5,6-difluoro-benzothiadiazole, 2,6-dimethylbenzenethiol, potassium carbonate is 1.8-2.2: 4.1-4.2: 18-22.

[0042] Further preferably, after stirring at room temperature for 12 h, the filtrate is collected by cooling filtration, the reaction solvent is removed by rotary evaporation, and then the compound 5,6-bis(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole is obtained by column chromatography separation and purification using petroleum ether / dichloromethane as eluent.

[0043] d. In a reaction vessel, perfluoro-benzothiadiazole, 1,2-benzenedithiol, potassium carbonate are added under argon atmosphere, and N,N-dimethylformamide is injected. The mixture is stirred at room temperature for 12 h to obtain compound benzo[5',6'][1,4]dithiino[2',3':3,4]thianthrene[1,2-c][1,2,5]thiadiazole, having the structural formula Preferably, the molar mass ratio of perfluoro-benzothiadiazole, 1,2-benzenedithiol, potassium carbonate is 1.8-2.2: 4.1-4.2: 18-22.

[0044] e. In a reaction vessel, 4,7-difluoro-1,3-dioxoisoindoline-2-carbonitrile, 2,6-dimethylbenzenethiol, potassium carbonate are added under argon atmosphere, and N,N-dimethylformamide is injected. The mixture is stirred at room temperature for 12 h to obtain compound 4,7-bis(2,6-dimethylphenyl)thio)-1,3-dioxoisoindoline-2-carbonitrile, having the structural formula Preferably, the molar mass ratio of 4,7-difluoro-1,3-dioxoisoindoline-2-carbonitrile, 2,6-dimethylbenzenethiol, potassium carbonate is 1.8-2.2: 4.1-4.2: 18-22.

[0045] f. Add 5,6-difluoro-1,3-dioxoisoindoline-2-carbamate, 1,2-benzenedithiophenol, and potassium carbonate to a reaction vessel. Under an argon atmosphere, inject N,N-dimethylformamide. Stir the mixture at room temperature for 12 h to obtain compound 1,3-dioxo-1,3-dihydro-2H-benzo[5,6][1,4]thiathanthracene[2,3-f]-isoindoline-2-carbamate, with the following structural formula: Preferably, the molar mass ratio of 5,6-difluoro-1,3-dioxoisoindoline-2-carbamate, 1,2-benzenedithiophenol, and potassium carbonate is 1.8-2.2:1.8-2.2:18-22;

[0046] More preferably, after stirring at room temperature for 12 hours, the filtrate is collected by cooling and filtration, the reaction solvent is removed by rotary evaporation, and then purified by column chromatography using petroleum ether / dichloromethane as the eluent to obtain compound 1,3-dioxo-1,3-dihydro-2H-benzo[5,6][1,4]thiathanthracene[2,3-f]-isoindole-2-carbamate.

[0047] g. Add 5,6-difluoro-1,3-dioxoisoindoline-2-carbamate, 2,6-dimethylbenzylthiophenol, and potassium carbonate to a reaction vessel. Inject tetrahydrofuran under an argon atmosphere. Stir the mixture at room temperature for 12 h to obtain compound 5,6-bis((2,6-dimethylphenyl)thio)-1,3-dioxoisoindoline-2-carbamate. Its structural formula is as follows: Preferably, the molar mass ratio of 5,6-difluoro-1,3-dioxoisoindoline-2-carbamate, 2,6-dimethylbenzylthiophenol, and potassium carbonate is 1.8-2.2:4.1-4.2:18-22;

[0048] More preferably, after stirring at room temperature for 12 hours, the filtrate is collected by cooling and filtration, the reaction solvent is removed by rotary evaporation, and petroleum ether / dichloromethane is used as the eluent to obtain compound 5,6-bis((2,6-dimethylphenyl)thio)-1,3-dioxoisoindoline-2-carbamate.

[0049] h. Add 4,5,6,7-tetrafluoro-1,3-dioxoisoindoline-2-carbamate, 1,2-benzenedithiophenol, and potassium carbonate to a reaction vessel. Under an argon atmosphere, inject N,N-dimethylformamide. Stir the mixture at room temperature for 12 h to obtain compound 6,8-dioxo-6,8-dihydro-7H-benzo[5,6][1,4]thiathianthracene[2,3-e]benzo[5,6][1,4]thiathianthracene[2,3-g]-isoindoline-2-carbamate, with the following structural formula: Preferably, the molar mass ratio of 4,5,6,7-tetrafluoro-1,3-dioxoisoindoline-2-carbamate, 1,2-benzenedithiophenol, and potassium carbonate is 1.8-2.2:4.1-4.2:18-22.

[0050] i. adding 2,5-difluoro-6b,10a-dihydroacenaphthylene[1,2-b]pyrazine-8,9-dicarbonitrile, 2,6-dimethylbenzenethiol, potassium carbonate into a reaction container, injecting N,N-dimethylformamide under argon atmosphere, stirring the mixture at room temperature for 12h to obtain compound 2,5-bis((2,6-dimethylphenyl)thio)-6b,10a-dihydroacenaphthylene[1,2-b]pyrazine-8,9-dicarbonitrile, whose structural formula is Preferably, the molar mass ratio of 2,5-difluoro-6b,10a-dihydroacenaphthylene[1,2-b]pyrazine-8,9-dicarbonitrile, 2,6-dimethylbenzenethiol, potassium carbonate is 1.8-2.2:4.1-4.2:18-22;

[0051] Further preferably, after stirring at room temperature for 12h, the filtrate is collected by cooling filtration, the reaction solvent is removed by rotary evaporation, and petroleum ether / dichloromethane is used as an eluent to obtain compound 2,5-bis((2,6-dimethylphenyl)thio)-6b,10a-dihydroacenaphthylene[1,2-b]pyrazine-8,9-dicarbonitrile.

[0052] j. adding 3,4-difluoro-6b,10a-dihydroacenaphthylene[1,2-b]pyrazine-8,9-dicarbonitrile, 2,6-dimethylbenzenethiol, potassium carbonate into a reaction container, injecting N,N-dimethylformamide under argon atmosphere, stirring the mixture at room temperature for 12h to obtain compound 3,4-bis((2,6-dimethylphenyl)thio)-6b,10a-dihydroacenaphthylene[1,2-b]pyrazine-8,9-dicarbonitrile, whose structural formula is Preferably, the molar mass ratio of 3,4-difluoro-6b,10a-dihydroacenaphthylene[1,2-b]pyrazine-8,9-dicarbonitrile, 2,6-dimethylbenzenethiol, potassium carbonate is 1.8-2.2:4.1-4.2:18-22;

[0053] Further preferably, after stirring at room temperature for 12h, the filtrate is collected by cooling filtration, the reaction solvent is removed by rotary evaporation, and petroleum ether / dichloromethane is used as an eluent to obtain compound 3,4-bis((2,6-dimethylphenyl)thio)-6b,10a-dihydroacenaphthylene[1,2-b]pyrazine-8,9-dicarbonitrile.

[0054] The application also provides an application of the double-emission thermally activated delayed fluorescence material, and the double-emission thermally activated delayed fluorescence material is used in the field of anti-counterfeiting and the field of information encryption.

[0055] The application has the following beneficial effects:

[0056] The double-emission external heat activated delayed fluorescence molecular structure provided by the application is novel, a D-A structure skeleton is formed through appropriate selection of a donor and an acceptor, and the excitation state energy level is regulated by adjusting the sulfur atom connection site of the donor and the acceptor; and further, the S2 and S3 sites are preferred, to obtain a preferred double-emission TADF material. The double-emission delayed lifetime provided by the application can reach 58.6 mu s and 3.4 ms, and higher accuracy and sensitivity can be achieved in application.

[0057] The double-emission external heat activated delayed fluorescence material provided by the application has a simple synthesis method, high yield, low preparation cost, and is easy to popularize and use in industry.

[0058] The double-emission TADF material provided by the application can inhibit non-radiative transition through hydrogen bonding with a PVA matrix doped film, prolong the lifetime of a triplet exciton, and has outstanding application in multi-dimensional anti-counterfeiting and information encryption. BRIEF DESCRIPTION OF DRAWINGS

[0059] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0060] Figure 1 The emission spectrum of the product prepared for Example 3 in a single crystal state; 1 H NMR spectrum;

[0061] Figure 2 The emission spectrum of the product prepared for Example 3 in a single crystal state;

[0062] Figure 3 The lifetime spectrum of the product prepared for Example 3 at 460 nm;

[0063] Figure 4 The lifetime spectrum of the product prepared for Example 3 at 630 nm;

[0064] Figure 5 The application test result graph of the product prepared for Example 3 when it is formed into a film with PVA in multi-dimensional anti-counterfeiting. DETAILED DESCRIPTION

[0065] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0066] The raw materials and reagents used in the following examples are commercially available.

[0067] Example 1

[0068] This embodiment provides a dual-emission thermally activated delayed fluorescence material 4,7-di(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole, which has a structural formula of The preparation method thereof is as follows:

[0069] In a reaction vessel, 4,7-difluoro-benzothiadiazole (343.0 mg, 2 mmol), 2,6-dimethylthiophenol (552.2 mg, 4 mmol), potassium carbonate solid (2.76 g, 20 mmol) were added, and under an argon atmosphere, tetrahydrofuran 30 mL was injected, and the mixture was stirred at room temperature for 12 h; then, the filtrate was collected by cooling and filtering, and the reaction solvent was removed by rotary evaporation, and then column chromatography separation and purification were performed, using petroleum ether / dichloromethane as the eluent, to obtain a yellow solid, which was 4,7-di(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole (GS1).

[0070] The calculated yield was 82.5%. The measured yield was 1 H NMR (600 MHz, DMSO-d6) δ 7.34 (dd, J = 6.3 Hz, 2H), 7.28 (d, J = 7.7 Hz, 4H), 2.34 (s, 12H).

[0071] Example 2

[0072] This embodiment provides a dual-emission thermally activated delayed fluorescence material thianthrene[2,3-c][1,2,5]-thiadiazole, which has a structural formula of The preparation method thereof is as follows:

[0073] 5,6-Difluoro-benzothiadiazole (343.0 mg, 2 mmol), 1,2-benzyl dithiophenol (283.9 mg, 2 mmol), and potassium carbonate (2.76 g, 20 mmol) were added to a reaction vessel. Under an argon atmosphere, 30 mL of N,N-dimethylformamide was injected, and the mixture was stirred at room temperature for 12 h. The filtrate was collected after cooling and filtration. The reaction solvent was removed by rotary evaporation, followed by purification by column chromatography using petroleum ether / dichloromethane as the eluent. The resulting pale yellow solid was thiaanthra[2,3-c][1,2,5]-thiadiazole.

[0074] The calculated yield was 92%. (Measured...) 1 H NMR (600MHz, CDCl3) δ8.15 (s, 2H), 7.58 (q, J = 8.7Hz, 2H), 7.34 (q, J = 8.9Hz, 2H).

[0075] Example 3

[0076] This embodiment provides a dual-emission thermally activated delayed fluorescence material, 5,6-bis(2,6-dimethylthiobenzene)benzo[c][1,2,5]thiadiazole, with the following structural formula: Its preparation method is as follows:

[0077] 5,6-Difluoro-benzothiadiazole (343.0 mg, 2 mmol), 2,6-dimethylbenzylthiophenol (552.2 mg, 4 mmol), and potassium carbonate (2.76 g, 20 mmol) were added to a reaction vessel. Under an argon atmosphere, 30 mL of tetrahydrofuran was injected, and the mixture was stirred at room temperature for 12 h. The filtrate was collected after cooling and filtration. The reaction solvent was removed by rotary evaporation, and then recrystallized from methanol / dichloromethane to obtain a light yellow solid, which is 5,6-bis(2,6-dimethylthiobenzene)benzo[c][1,2,5]thiadiazole.

[0078] The calculated yield was 86.7%. (Measured...) 1 ¹H NMR (600MHz, DMSO-d⁶) δ 7.47 (dd, J = 6.9Hz, 2H), 7.41 (d, J = 7.8Hz, 4H), 2.44 (s, 12H), spectrum as shown. Figure 1 As shown, by Figure 1 It can be seen that this embodiment successfully produced...

[0079] Figure 2 The emission spectrum of the product in this embodiment in the single-crystal state is shown by [the following text is missing from the original] Figure 2 It can be seen that the product obtained in this embodiment The dual emission occurs at 460nm and 630nm, respectively.

[0080] Figure 3The lifetime spectrum of the product prepared in this example at 460 nm is shown in the following figure: Figure 3 It can be seen that the lifetime of the product prepared in this example at 460 nm reached 58.6 μs.

[0081] Figure 4 The lifetime spectrum of the product prepared in this example at 630 nm is shown in the following figure: Figure 4 It can be seen that the lifetime of the product prepared in this example at 630 nm reached 3.48 ms.

[0082] Example 4

[0083] This example provides a dual-emission thermally activated delayed fluorescence material benz[5',6'] [1,4] dithiyl [2',3':3,4] thianthrene [1,2-c] [1,2,5] thiadiazole, which has the structural formula The preparation method is as follows:

[0084] In a reaction vessel, perfluoro-benzothiadiazole (415.9 mg, 2 mmol), 1,2-benzenedithiol (576.9 mg, 4 mmol), potassium carbonate (2.76 g, 20 mmol) were added, 30 mL of N,N-dimethylformamide was injected under argon atmosphere, and the mixture was stirred at room temperature for 12 h. The filtrate was collected by cooling and filtration, and the reaction solvent was removed by rotary evaporation, followed by column chromatography separation and purification, using petroleum ether / dichloromethane as the eluent, to obtain an orange solid, which was benz[5',6'] [1,4] dithiyl [2',3':3,4] thianthrene [1,2-c] [1,2,5] thiadiazole, with a calculated yield of 79.7%.

[0085] Example 5

[0086] This example applies the dual-emission thermally activated delayed fluorescence material 5,6-di(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole provided in Example 3 to the field of multi-dimensional anti-counterfeiting, with the specific steps as follows:

[0087] The compound 5,6-di(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole was mixed with polyvinyl alcohol (PVA) according to a 1% doping ratio, and the mixture was thoroughly stirred and uniformly mixed, then spread on a clean quartz sheet, and the solvent was dried in an oven at 40°C to obtain a uniform transparent colorless film. The films obtained using different film-forming solvents showed different anti-counterfeiting effects in three colors and different afterglow lifetimes when irradiated with a 365 nm ultraviolet lamp; and also showed different anti-counterfeiting effects in two colors and different afterglow lifetimes when irradiated with different 365 nm and 405 nm ultraviolet lamps.

[0088] Figure 5The image shows the application test results of the product obtained in Example 3 after being formed into a thin film with PVA for multi-dimensional anti-counterfeiting. Figure 5 (a) A film prepared by dissolving the product in different solvents and displayed under 365 nm light. Figure 5 (b) Images showing the film prepared using DMSO as solvent under illumination at 365 nm and 405 nm. Figure 5 (a) It can be seen that colorless films were prepared by dissolving the sample with THF, ACN, and DMSO using these three solvents and then mixing them with PVA. The film prepared with THF showed a blue "I" under 365nm illumination, the film prepared with ACN showed a pink "M" under 365nm illumination, and the film prepared with DMSO showed a red "U" under 365nm illumination. After the illumination was turned off, red "IMU" films with varying afterglow lengths could be observed. The colorless film prepared by dissolving the sample with DMSO and then mixing it with PVA was... Figure 5 (b) It can be seen that the inscription "Inner Mongolia University" is red under 365nm illumination and pink under 405nm illumination. Even after the illumination is turned off, a red afterglow of "Inner Mongolia University" can still be observed. This indicates that the dual-emission thermally activated delayed fluorescence material provided by this invention exhibits a unique color change under specific wavelengths of light. Furthermore, it demonstrates extremely high stability under various environmental conditions, resisting deterioration or fading. This allows the anti-counterfeiting effect of the dual-emission thermally activated delayed fluorescence material provided by this invention to be maintained for a relatively long period. This optical characteristic is difficult to imitate and makes it an ideal anti-counterfeiting material.

[0089] Comparative Example 1

[0090] Existing technologies have limited availability of materials with dual TADF emission, especially those with millisecond-level lifetimes suitable for multiple anti-counterfeiting applications. For example, in 2020, Luo et al. designed dual TADF emission M-1 based on the anti-Kasha rule, achieving a dual-emission delay lifetime of only tens of μs, which was used for dual-channel time-life imaging of HeLa cells (Angew. Chem. Int. Ed. 2020, 59, 17018–17025). In 2024, Shi et al. designed dual TADF emission PmPy-PXZ using molecular conformational isomerization, but the delay lifetime was only in the nanosecond range, failing to achieve anti-counterfeiting applications (CCS Chemistry. 2024, 6, 912–922).

[0091] The dual-emission system provided by this invention has a delay lifetime of 58.6μs and 3.48ms, which can leverage its long lifespan advantage in multiple anti-counterfeiting applications.

[0092] Please note that the technical features of the above embodiments can be combined in any manner, and for the sake of brevity, not all possible combinations of the technical features in the above embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered as within the scope of the present disclosure. The above embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but should not be understood as a limitation on the patent scope of the present application. It should be noted that for those skilled in the art, some modifications and improvements can be made without departing from the concept of the present application, and these are within the scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. Use of a dual-emissive thermally activated delayed fluorescence material, characterized in that, The double-emission thermally activated delayed fluorescence material is suitable for the field of anti-counterfeiting. The fluorescent material forms a D-A skeleton structure from a donor and an acceptor, and the excitation state energy level of the material is regulated by regulating the sulfur atom connection sites of the donor and the acceptor. The structural formula of the donor is The acceptor is 2,1,3-benzothiadiazole, and the structural formula is The sulfur atom connection sites of the donor and the acceptor are S2 and S3. The fluorescent material has a structural formula of ; R is any one of hydrogen, methyl and tert-butyl; R at different sites is the same or different. Z is sulfur.

2. Use of a dual-emission heat-activated delayed fluorescent material according to claim 1, wherein The donor is 2,6-dimethylbenzenethiol.

3. Use of a dual-emission heat-activated delayed fluorescent material according to claim 1, wherein The preparation method of the double-emission thermally activated delayed fluorescence material comprises the following steps: mixing the acceptor precursor, the donor and potassium carbonate, and injecting the mixture into a solvent under an argon atmosphere, and stirring to react, so that the double-emission thermally activated delayed fluorescence material is obtained. The solvent is any one of tetrahydrofuran and N,N-dimethylformamide.

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