Dual-emission thermal activation delayed fluorescence material and preparation method and application thereof

Abstract

The invention provides a dual-emission thermally activated delayed fluorescent material as well as a preparation method and application thereof. According to the dual-emission thermally activated delayed fluorescent material, a D-A skeleton structure is formed by a donor and an acceptor, and the excited state energy level of the material is regulated and controlled by regulating and controlling sulfur atom connecting sites of the donor and the acceptor. The dual-emission thermally activated delayed fluorescent material is prepared by the preparation method, and the preparation method comprises the following steps: mixing an acceptor precursor, a donor and potassium carbonate, injecting a solvent in an argon atmosphere, and stirring for reaction; the solvent is prepared from any one of tetrahydrofuran and N, N-dimethylformamide. The dual-emission thermal activation delayed fluorescence material is suitable for the anti-counterfeiting field and the information encryption field. The dual-emission delay life of the dual-emission thermally activated delayed fluorescent material can reach 58.6 microseconds and 3.4 ms respectively, the preparation method is simple, the repeatability is high, the yield is high, non-radiative transition is inhibited through hydrogen-bond interaction after film forming, the triplet exciton life is prolonged, and the dual-emission thermally activated delayed fluorescent material has large-scale popularization and application prospects in the multi-dimensional anti-counterfeiting field.

Description

Technical Field

[0001] The invention belongs to the technical field of organic luminescent materials, and in particular relates to a dual-emission thermally activated delayed fluorescent material and a preparation method and application thereof. Background Art

[0002] Thermally activated delayed fluorescence materials, namely TADF materials, are the third generation of delayed fluorescence materials with pure organic structures developed after fluorescent materials and precious metal phosphorescent materials. They break through the limit of exciton utilization of traditional fluorescent molecular materials and achieve 100% exciton utilization, thereby greatly improving the quantum efficiency of OLEDs. The characteristic of TADF materials is 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 to S1 through the reverse intersystem crossing (RISC) process under thermal assistance, and radiate light. Since the RISC process is slower than the radiation process of S1, the fluorescence generated is called delayed fluorescence. Its typical characteristics are a small singlet-triplet energy gap and positive temperature dependence.

[0003] Most traditional TADF molecules only exhibit single emission characteristics, which limits their in-depth application in the fields of multicolor luminescence and multifunctional fluorescent probes. Therefore, the development of TADF molecules with dual emission characteristics has become a hot topic in current research.

[0004] At present, the design strategy of dual-emission TADF molecules is mainly to regulate the multiple conformations of the molecules. Wang et al. designed and synthesized the compound 2-(9,9-dimethylacridine-10(9H)-yl)-3-phenylthiaquinone-5,5,10,10-tetraoxide (DMAC-PTR). Due to the huge steric hindrance, there are near-planar conformations and almost orthogonal conformations (82°). This dual conformation conversion is the key to achieving 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 exhibit conformation-dependent luminescence based on three conformers of over-twisted, twisted and planar isomers (Zhu C.etal.J.Am.Chem.Soc.2023,145,16748-16759). However, the chemical structures that realize these functions are often complex and difficult to precisely control, which greatly limits their breadth and reliability in practical applications. Therefore, the subsequent regulation of the charge transfer excited state energy levels between different donors and acceptors in the molecule reduces the energy gap (ΔEST) between S1 and T1, thereby facilitating the occurrence of the RISC process and further regulating the characteristics of the dual emission. Hua et al. prepared an orange-red TADF emitter with a three-dimensional structure by attaching tert-butyl modified naphthylbenzamide-dimethylacridine as a TADF unit to a TNP unit, with a SOC value of 0.862cm -1 , is an excellent strategy for excited state regulation and design of high-performance TADF emitters (Hua L. et al. Nat. Commun. 2022, 13, 7828). However, the large number of complicated synthesis processes limits the depth of promotion.

[0005] Therefore, for TADF materials with dual-emission characteristics, how to achieve precise control of the structure of dual-emission TADF materials while simplifying their preparation steps is a technical challenge that needs to be overcome in this field.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The object of the present invention is to provide a dual-emission thermally activated delayed fluorescent material and a preparation method and application thereof, so as to solve the above problems.

[0008] In order to achieve the above objectives, the present invention particularly adopts the following technical solutions:

[0009] A dual-emission thermally activated delayed fluorescent material, which is formed by a DA skeleton structure of a donor and an acceptor, and the excited state energy level of the material is regulated by regulating the sulfur atom connection sites of the donor and the acceptor. The present application further achieves the regulation of the TADF properties of the material molecule by regulating the excited state energy level of the material.

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

[0011] Wherein R is any one of hydrogen (-H), methyl (-CH3), and tert-butyl (-C(CH3)3);

[0012] R at different sites may be the same or different.

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

[0014] Optionally, the acceptor includes 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 receptor includes:

[0016]

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

[0018] T is any one of cyano group (-CN), keto group (-CO), and aromatic ring group (-Ar), and T at different positions may be the same or different.

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

[0020] Optionally, the structural formula of the fluorescent material includes 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); R at different sites is the same or different;

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

[0025] T is any one of cyano group (-CN), keto group (-CO), and aromatic ring group (-Ar), and T at different positions may be the same or different.

[0026] Optionally, the structural formula of the fluorescent material may be 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 invention provides a method for preparing the dual-emission thermally activated delayed fluorescent material, the method comprising: mixing the acceptor precursor, the donor, and potassium carbonate, injecting a solvent under an argon atmosphere, and stirring the reaction to obtain the dual-emission thermally activated delayed fluorescent material;

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

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

[0037] Optionally, the method comprises:

[0038] a. Add 4,7-difluoro-benzothiadiazole, 2,6-dimethylthiophenol, and potassium carbonate solid into a reaction vessel, inject tetrahydrofuran under argon atmosphere, and stir the mixture at room temperature for 12 hours to obtain a compound 4,7-bis(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole, whose structural formula is Preferably, the molar mass ratio of the 4,7-difluoro-benzothiadiazole, 2,6-dimethylthiophenol 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 hours, the filtrate is collected by cooling and filtration, the reaction solvent is removed by rotary evaporation, and then separated and purified by column chromatography using petroleum ether / dichloromethane as eluent to obtain the compound 4,7-bis(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole.

[0040] b. Add 5,6-difluoro-benzothiadiazole, 1,2-benzenedithiol, and potassium carbonate into a reaction vessel, and inject N,N-dimethylformamide under an argon atmosphere; stir the mixture at room temperature for 12 hours to obtain a compound thianthrene[2,3-c][1,2,5]-thiadiazole, whose structural formula is Preferably, the molar mass ratio of the 5,6-difluoro-benzothiadiazole, 1,2-benzenedithiol, and potassium carbonate is 1.8-2.2:1.8-2.2:18-22.

[0041] c. Add 5,6-difluoro-benzothiadiazole, 2,6-dimethylthiophenol, and potassium carbonate into a reaction vessel, and inject tetrahydrofuran under an argon atmosphere; stir the mixture at room temperature for 12 hours to obtain a compound 5,6-bis(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole, whose structural formula is Preferably, the molar mass ratio of the 5,6-difluoro-benzothiadiazole, 2,6-dimethylthiophenol, and potassium carbonate is 1.8-2.2:4.1-4.2:18-22.

[0042] Further 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 separated and purified by column chromatography using petroleum ether / dichloromethane as eluent to obtain the compound 5,6-bis(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole.

[0043] d. Add perfluoro-benzothiadiazole, 1,2-benzenedithiophenol, and potassium carbonate into the reaction vessel, and inject N,N-dimethylformamide under argon atmosphere. Stir the mixture at room temperature for 12 hours to obtain the compound benzo[5',6'][1,4]disulfide[2',3':3,4]thianthrene[1,2-c][1,2,5]thiadiazole, whose structural formula is Preferably, the molar mass ratio of perfluoro-benzothiadiazole, 1,2-benzenedithiol, and potassium carbonate is 1.8-2.2:4.1-4.2:18-22.

[0044] e. Add 4,7-difluoro-1,3-dihydroisoindoline-2-carbonitrile, 2,6-dimethylthiophenol, and potassium carbonate to the reaction vessel, and inject N,N-dimethylformamide under argon atmosphere. Stir the mixture at room temperature for 12 hours to obtain the compound 4,7-bis((2,6-dimethylphenyl)thio)-1,3-dihydroisoindoline-2-carbonitrile, whose structural formula is Preferably, the molar mass ratio of the 4,7-difluoro-1,3-dioxoisoindoline-2-carbonitrile, 2,6-dimethylthiophenol, and potassium carbonate is 1.8-2.2:4.1-4.2:18-22.

[0045] f. Add 5,6-difluoro-1,3-dioxoisoindoline-2-carbonitrile, 1,2-benzenedithiophenol, and potassium carbonate into the reaction vessel, and inject N,N-dimethylformamide under argon atmosphere. Stir the mixture at room temperature for 12 hours to obtain the compound 1,3-dioxo-1,3-dihydro-2H-benzo[5,6][1,4]thianthrene[2,3-f]-isoindole-2-carbonitrile, whose structural formula is Preferably, the molar mass ratio of 5,6-difluoro-1,3-dioxoisoindoline-2-carbonitrile, 1,2-benzenedithiophenol, and potassium carbonate is 1.8-2.2:1.8-2.2:18-22;

[0046] Further 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 separated and purified by column chromatography using petroleum ether / dichloromethane as eluent to obtain compound 1,3-dioxy-1,3-dihydro-2H-benzo[5,6][1,4]thianthrene[2,3-f]-isoindole-2-carbonitrile.

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

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

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

[0050] i. Add 2,5-difluoro-6b,10a-dihydroacenaphthene[1,2-b]pyrazine-8,9-dicarbonitrile, 2,6-dimethylthiophenol, and potassium carbonate to a reaction vessel, and inject N,N-dimethylformamide under an argon atmosphere. Stir the mixture at room temperature for 12 hours to obtain the compound 2,5-bis((2,6-dimethylphenyl)thio)-6b,10a-dihydroacenaphthene[1,2-b]pyrazine-8,9-dicarbonitrile, whose structural formula is Preferably, the molar mass ratio of 2,5-difluoro-6b,10a-dihydroacenaphthene[1,2-b]pyrazine-8,9-dicarbonitrile, 2,6-dimethylthiophenol, and potassium carbonate is 1.8-2.2:4.1-4.2:18-22;

[0051] Further 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 eluent to obtain compound 2,5-bis((2,6-dimethylphenyl)thio)-6b,10a-dihydroacenaphthene[1,2-b]pyrazine-8,9-dicarbonitrile.

[0052] j. Add 3,4-difluoro-6b,10a-dihydroacenaphthene[1,2-b]pyrazine-8,9-dicarbonitrile, 2,6-dimethylthiophenol, and potassium carbonate to a reaction vessel, and inject N,N-dimethylformamide under an argon atmosphere. Stir the mixture at room temperature for 12 hours to obtain the compound 3,4-bis((2,6-dimethylphenyl)thio)-6b,10a-dihydroacenaphthene[1,2-b]pyrazine-8,9-dicarbonitrile, whose structural formula is Preferably, the molar mass ratio of 3,4-difluoro-6b,10a-dihydroacenaphthene[1,2-b]pyrazine-8,9-dicarbonitrile, 2,6-dimethylthiophenol, and potassium carbonate is 1.8-2.2:4.1-4.2:18-22;

[0053] Further 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 eluent to obtain compound 3,4-bis((2,6-dimethylphenyl)thio)-6b,10a-dihydroacenaphthene[1,2-b]pyrazine-8,9-dicarbonitrile.

[0054] The present invention also provides an application of the dual-emission thermally activated delayed fluorescent material, and the dual-emission thermally activated delayed fluorescent material is used in the fields of anti-counterfeiting and information encryption.

[0055] Beneficial effects of the present invention:

[0056] The dual-emission external thermally activated delayed fluorescence molecular structure provided by the present invention is novel, and the DA structural skeleton is formed by selecting appropriate donors and acceptors, and the excited state energy level is regulated by adjusting the sulfur atom connection sites of the donors and acceptors; and further, the S2 and S3 sites are preferred to obtain the preferred dual-emission TADF material. The dual-emission delayed lifetime provided by the present invention can reach 58.6μs and 3.4ms, and higher accuracy and sensitivity can be achieved when applied.

[0057] The synthesis method of the dual-emission external thermally activated delayed fluorescent material provided by the invention is simple, has high yield, low preparation cost, and is easy to be promoted and used in industrialization.

[0058] The dual-emission TADF material and PVA matrix doped film provided by the present invention can inhibit non-radiative transitions through hydrogen bonding, prolong the lifetime of triplet excitons, and have outstanding applications in multi-dimensional anti-counterfeiting and information encryption. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0060] Figure 1 The product obtained in Example 3 1 H NMR spectrum;

[0061] Figure 2 This is the emission diagram of the product obtained in Example 3 in a single crystal state;

[0062] Figure 3 This is a lifetime diagram of the product obtained in Example 3 at 460 nm;

[0063] Figure 4 This is a lifetime diagram of the product obtained in Example 3 at 630 nm;

[0064] Figure 5 This is a graph showing the application test results of the product prepared in Example 3 and formed into a film with PVA in multi-dimensional anti-counterfeiting. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

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

[0067] Example 1

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

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

[0070] The calculated yield is 82.5%. 1 H NMR (600MHz, DMSO-d6) δ7.34 (dd, J = 6.3Hz, 2H), 7.28 (d, J = 7.7Hz, 4H), 2.34 (s, 12H).

[0071] Example 2

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

[0073] 5,6-difluoro-benzothiadiazole (343.0 mg, 2 mmol), 1,2-benzenedithiophenol (283.9 mg, 2 mmol), potassium carbonate (2.76 g, 20 mmol) were added to the reaction vessel, and 30 mL of N,N-dimethylformamide was injected under an 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, and then separated and purified by column chromatography using petroleum ether / dichloromethane as the eluent to obtain a light yellow solid, which was thianthrene [2,3-c] [1,2,5]-thiadiazole.

[0074] The calculated yield is 92%. 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 fluorescent material 5,6-bis(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole, whose structural formula is The preparation method is as follows:

[0077] 5,6-difluoro-benzothiadiazole (343.0 mg, 2 mmol), 2,6-dimethylthiophenol (552.2 mg, 4 mmol), potassium carbonate (2.76 g, 20 mmol) were added to the reaction vessel, and 30 mL of tetrahydrofuran was injected under argon atmosphere. 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. After that, the mixture was recrystallized with methanol / dichloromethane as solvent to obtain a light yellow solid, which was 5,6-bis(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole.

[0078] The calculated yield is 86.7%. 1 H NMR (600 MHz, DMSO-d6) δ7.47 (dd, J = 6.9 Hz, 2H), 7.41 (d, J = 7.8 Hz, 4H), 2.44 (s, 12H), the spectrum is shown in Figure 1 As shown by Figure 1 It can be seen that this embodiment successfully obtained

[0079] Figure 2 is the emission spectrum of the product of this embodiment in the single crystal state, Figure 2 It can be seen that the The dual emissions are at 460nm and 630nm respectively.

[0080] Figure 3is the lifetime spectrum of the product obtained in this example at 460nm, Figure 3 It can be seen that the lifetime of the product prepared in this embodiment at 460nm reaches 58.6μs.

[0081] Figure 4 is the lifetime diagram of the product obtained in this embodiment at 630nm, Figure 4 It can be seen that the lifetime of the product prepared in this embodiment at 630nm reaches 3.48ms.

[0082] Example 4

[0083] This embodiment provides a dual-emission thermally activated delayed fluorescent material benzo[5',6'][1,4]disulfide[2',3':3,4]thianthrene[1,2-c][1,2,5]thiadiazole, whose structural formula is The preparation method is as follows:

[0084] Perfluoro-benzothiadiazole (415.9 mg, 2 mmoL), 1,2-benzenedithiophenol (576.9 mg, 4 mmoL), potassium carbonate (2.76 g, 20 mmol) were added to the reaction vessel, and 30 mL of N,N-dimethylformamide was injected under an 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, and then separated and purified by column chromatography using petroleum ether / dichloromethane as an eluent to obtain an orange solid, namely benzo[5',6'][1,4]disulfide[2',3':3,4]thianthrene[1,2-c][1,2,5]thiadiazole, with a calculated yield of 79.7%.

[0085] Example 5

[0086] In this embodiment, the dual-emission thermally activated delayed fluorescent material 5,6-bis(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole provided in Example 3 is applied to the multi-dimensional anti-counterfeiting field, and the specific steps are as follows:

[0087] The compound 5,6-bis(2,6-dimethylthiophenyl)benzo[c][1,2,5]thiadiazole and polyvinyl alcohol (PVA) were prepared into a solution at a doping ratio of 1%, stirred and mixed thoroughly, and then spread on a clean quartz plate. 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 three different colors and different afterglow lifespans of anti-counterfeiting effects when illuminated by 365nm ultraviolet light; when illuminated by different 365nm and 405nm ultraviolet lights, they also showed two different colors and different afterglow lifespans of anti-counterfeiting effects.

[0088] Figure 5The figure is a test result of the application of the product prepared in Example 3 and PVA in multi-dimensional anti-counterfeiting after forming a film, wherein Figure 5 (a) is a diagram showing the film formation using different solvents to dissolve the product and the illumination at 365 nm. Figure 5 (b) is a diagram showing the film made with DMSO as solvent and illuminated at 365nm and 405nm. Figure 5 (a) It can be seen that three solvents, THF, ACN and DMSO, were used to dissolve the sample and PVA to make colorless films. The film made of THF showed blue "I" under 365nm light, the film made of ACN showed pink "M" under 365nm light, and the film made of DMSO showed red "U" under 365nm light. After turning off the light, red "IMU" with different afterglow lengths can be observed. Figure 5 (b) It can be seen that a red "Inner Mongolia University" is obtained under 365nm illumination, and a pink "Inner Mongolia University" is obtained under 405nm illumination. After turning off the illumination, the red afterglow of "Inner Mongolia University" can be observed. This shows that the dual-emission thermally activated delayed fluorescent material provided by the present invention will show a unique color change under illumination of a specific wavelength. At the same time, it shows extremely high stability under various environmental conditions and is not easy to deteriorate or fade, which enables the anti-counterfeiting effect of the dual-emission thermally activated delayed fluorescent material provided by the present invention to be maintained for a relatively long time. This optical property is difficult to imitate and can be used as an ideal anti-counterfeiting material.

[0089] Comparative Example 1

[0090] There are few materials with dual TADF emission in the prior art, especially those with lifetimes up to ms and that can be used for multiple anti-counterfeiting applications. Among them, in 2020, Luo et al. designed dual TADF emitter M-1 according to the anti-Kasha rule. The dual emission delay lifetime was 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 emitter PmPy-PXZ using molecular conformational isomerization. The delay lifetime was only at the ns level, which could not achieve anti-counterfeiting applications (CCS Chemistry. 2024, 6, 912–922).

[0091] The dual emission provided by the present invention has a delay life of 58.6 μs and 3.48 ms, and can take advantage of the long life in multiple anti-counterfeiting applications.

[0092] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above embodiments only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all belong to the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.

Claims

1. A dual-emission thermally activated delayed fluorescent material, characterized in that: The fluorescent material forms a DA skeleton structure with a donor and an acceptor, and the excited state energy level of the material is regulated by regulating the sulfur atom connection sites of the donor and the acceptor.

2. The dual-emission thermally activated delayed fluorescent material according to claim 1, characterized in that: The structural formula of the donor includes Wherein R is any one of hydrogen (-H), methyl (-CH3), and tert-butyl (-C(CH3)3); R at different sites may be the same or different.

3. The dual-emission thermally activated delayed fluorescent material according to claim 1 or 2, characterized in that: The donor includes 2,6-dimethylbenzenethiol and 1,2-benzenedithiol.

4. The dual-emission thermally activated delayed fluorescent material according to claim 1, characterized in that: The receptor includes any one or more of 2,1,3-benzothiadiazole, 1,3-dioxoisoindole-2-carbonitrile, and acenaphtho[1,2-b]quinoxaline-9,10-dicarbonitrile.

5. The dual-emission thermally activated delayed fluorescent material according to claim 1 or 4, characterized in that: The structural formula of the receptor includes: wherein Z is sulfur (S) or selenium (Se); T is any one of cyano group (-CN), keto group (-CO), and aromatic ring group (-Ar), and T at different positions may be the same or different.

6. The dual-emission thermally activated delayed fluorescent material according to claim 5, characterized in that: The sulfur atom connection sites of the donor and the acceptor include any one or more of S1, S2, S3, and S4.

7. The dual-emission thermally activated delayed fluorescent material according to claim 1, characterized in that: The structural formula of the fluorescent material includes any one of the following structural formulas: Wherein R is any one of hydrogen (-H), methyl (-CH3), and tert-butyl (-C(CH3)3); R at different sites is the same or different; Z is sulfur (S) or selenium (Se); T is any one of cyano group (-CN), keto group (-CO), and aromatic ring group (-Ar), and T at different positions may be the same or different.

8. The dual-emission thermally activated delayed fluorescent material according to claim 6, characterized in that: The sulfur atom connection sites of the donor and the acceptor are S2 and / or S3.

9. A method for preparing a dual-emission thermally activated delayed fluorescent material according to any one of claims 1 to 8, characterized in that: The method comprises: mixing the acceptor precursor, the donor and potassium carbonate, injecting a solvent under an argon atmosphere, and stirring for reaction to obtain the dual-emission thermally activated delayed fluorescent material; The solvent includes any one of tetrahydrofuran and N,N-dimethylformamide.

10. Use of the dual-emission thermally activated delayed fluorescent material according to any one of claims 1 to 8, characterized in that: The dual-emission thermally activated delayed fluorescent material is suitable for the fields of anti-counterfeiting and information encryption.

Images