Small molecule receptor taking benzothiadiazolo selenadiazole as core as well as preparation and application of small molecule receptor

Abstract

The invention discloses a small molecule receptor taking benzothiadiazoloselenadiazole as a core as well as preparation and application of the small molecule receptor, and relates to the technical field of organic photoelectric materials. The preparation method comprises the following steps: by taking 4, 7-dibromo-2, 1, 3-benzothiadiazole as a raw material, firstly obtaining a benzothiadiazole selenadiazole core through nitration, reduction and ring closing, and then constructing an aldehyde group and organic tin group substituted cyclopentyl bithiophene module by taking cyclopentyl bithiophene as a raw material. And condensing the benzothiadiazoloselenadiazole core and a cyclopentyl bithiophene module, and reacting by using a terminal group unit 3-(dicyanomethylene) indanone and a derivative thereof to obtain a target compound. Benefited from the strong electron-withdrawing property and rigid planarity of the benzothiadiazoloselenadiazole core and the non-covalent interaction potential introduced by selenium atoms, the small molecule receptor shows good three-dimensional charge transfer characteristic, tight intermolecular accumulation and relatively high electron mobility, and when the small molecule receptor is applied to a binary organic photoelectric detector, the electron mobility of the small molecule receptor is greatly improved. The material is expected to show excellent near-infrared light detection performance.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic materials technology, specifically to small molecule acceptors with benzothiadiazole and selenium diazole as the core, and their preparation and application. Background Technology

[0002] With the ever-increasing demand for applications in environmental sensing, biomedical imaging, security monitoring, and optical communication, photodetectors capable of detecting the near-infrared spectral region are receiving unprecedented attention. While traditional inorganic detectors have applications in the near-infrared region, they suffer from limitations such as high cost, complex fabrication, brittleness, difficulty in large-area fabrication, and challenges in integration with flexible electronics. Therefore, developing novel, high-performance, low-cost, solution-processable, and flexible near-infrared photodetectors is of great significance.

[0003] Organic photodetectors have become a highly promising alternative due to their advantages such as wide availability of materials, low cost, high light absorption coefficient, light weight, good flexibility, and simple manufacturing process. In recent years, organic photodetectors have made significant progress in key performance parameters, especially detectivity, responsivity, and response speed. Their performance has approached or even surpassed that of traditional inorganic detectors in some aspects, paving the way for large-scale commercial applications. The core challenge in current research on high-performance near-infrared organic photodetectors lies in how to design and synthesize active layer materials that can efficiently absorb near-infrared photons, ensure efficient dissociation of photoexcitons, and enable the generated charge carriers to be transported quickly and with low loss and effectively collected by electrodes, while maintaining extremely low dark current noise. Therefore, the design and development of high-performance acceptor materials are crucial. Ideal near-infrared organic photodetector materials require broad and strong absorption in the near-infrared region, appropriate HOMO and LUMO energy levels, high electron mobility, good stability, solubility, and film-forming properties, and good compatibility with donor materials. In recent years, the rapid development of non-fullerene small molecule acceptors has greatly promoted the research of high-performance organic photodetectors, especially in extending the near-infrared response. Compared with traditional fullerene derivatives, non-fullerene small molecule acceptors have significant advantages such as ease of synthesis and purification, lower cost, high solubility, and easily tunable absorption spectra (especially the ability to design narrow optical band gaps to cover the near-infrared region), and can achieve good matching with a wide range of donor materials. Designing non-fullerene small molecules with AD-A'-DA structures is one of the recent hot strategies. These molecules typically exhibit strong intramolecular charge transfer (ICT) effects, strong intermolecular interactions, easily finely tunable energy levels (facilitating optimization of exciton dissociation and reduction of dark current), and narrow optical band gaps (facilitating near-infrared absorption). Summary of the Invention

[0004] The purpose of this invention is to provide a small molecule acceptor with benzothiadiazole-selenodiazole as its core, its preparation, and its application. Benefiting from the strong electron-withdrawing properties, rigid planarity, and non-covalent interaction potential introduced by the selenium atom in the benzothiadiazole-selenodiazole core, the material is expected to exhibit excellent three-dimensional charge transport properties, tight intermolecular packing, and high electron mobility. When applied to binary organic photodetectors, this material is expected to exhibit superior near-infrared light detection performance.

[0005] Based on the above objectives, this invention discloses a small molecule receptor with benzothiadiazole selenidediazole as its core. This small molecule receptor is an AD-A'-DA structured conjugated non-fullerene organic small molecule, and its molecular structure is shown in Formula I:

[0006]

[0007] Wherein, R group is alkyl, and the molecular formula is C m H 2m+1 , where m is an integer greater than or equal to 1; X group is a hydrogen group, a halogen group or a pseudohalogen group.

[0008] Preferably, X is H, F, Cl, Br or CN.

[0009] Preferably, the R group is 2-ethylethane, 2-butylbutane, or 2-hexyldecane.

[0010] Preferably, the structural formula of the small molecule receptor with benzothiadiazole selenidediazole as the core is as follows:

[0011]

[0012] This invention utilizes a small-molecule acceptor core structure with benzothiadiazole and selenium diazole as its core. This structure is formed by the fusion of strongly electron-withdrawing thiadiazole and selenium diazole units. Compared to traditional aromatic conjugated systems, benzothiadiazole and selenium diazole, as the central unit, possess extremely strong electron-withdrawing capabilities, significantly enhancing intramolecular charge transfer effects, effectively reducing the LUMO energy level of the material, and compressing the optical band gap, allowing its absorption spectrum to extend deeper into the near-infrared region. The benzothiadiazole and selenium diazole structure itself has a highly rigid planar framework, which helps reduce intramolecular disorder and torsion, promotes effective intermolecular π-π stacking, and improves the crystallinity and order of the film. This ordered structure is a key foundation for achieving high electron mobility. The selenium atoms introduced into the structure not only contribute to the strong electron-withdrawing property but also further strengthen intermolecular forces through non-covalent interactions such as Se-Se or Se-S, optimizing the molecular arrangement and packing density in the solid state, and providing favorable conditions for the formation of a three-dimensional charge transport network. Benzothiadiazole selenide diazole belongs to a stable aromatic heterocyclic system. Compared with some quinone structures, it usually has excellent chemical and photochemical stability, which is beneficial for the long-term operation of devices.

[0013] This invention also provides the preparation of the above-mentioned small molecule acceptor with benzothiadiazole selenide diazole as the core. Using 4,7-dibromo-2,1,3-benzothiadiazole as a starting material, the benzothiadiazole selenide diazole core is first obtained through nitration, reduction, and cyclization. Then, a cyclopentylthiophene module substituted with aldehyde and organotin groups is constructed using cyclopentylthiophene as a starting material. After condensing the benzothiadiazole selenide diazole core with the cyclopentylthiophene module, the target compound is obtained by reacting it with the terminal unit 3-(dicyanomethylene)indone and its derivatives. The process includes the following steps:

[0014] (1) Under an argon atmosphere and at 0°C, trifluoromethanesulfonic anhydride and nitric acid were added sequentially to a sulfolane solution of compound 4,7-dibromo-2,1,3-benzothiadiazole. The mixture was stirred at room temperature for 1 hour, then heated to 90°C and stirred overnight. After the reaction was complete, the reactants were poured into water. The solid was collected by filtration. Yellow solid A was recrystallized from anhydrous ethanol. The structural formula of compound A is:

[0015]

[0016] (2) Under an argon atmosphere, glacial acetic acid was used as the solvent, and compound A was used as the raw material. The mixture was stirred with iron powder at 45°C for 8 hours. After the reaction was completed and cooled to room temperature, the reaction solution was poured into a 5% sodium hydroxide aqueous solution. The organic phase was extracted with ethyl acetate, dried over anhydrous Na₂SO₄, and the solvent was removed under reduced pressure to obtain a deep yellow crude solid, compound B. The structural formula of compound B is:

[0017]

[0018] (3) Under an argon atmosphere, a mixed solution of anhydrous ethanol and tetrahydrofuran was used as the solvent, and compound B was used as the raw material. An ethanol solution of selenium dioxide was slowly added dropwise, and the mixture was stirred overnight at 75°C. After the reaction was complete, the mixture was cooled to room temperature, the organic phase was extracted with chloroform, dried over anhydrous Na₂SO₄, and the solvent was removed under reduced pressure to obtain a green solid crude compound C. The structural formula of compound C is:

[0019]

[0020] (4) Under an argon atmosphere and at 0°C, bromoalkyl groups, potassium iodide, and potassium hydroxide were added sequentially to a DMSO solution of cyclopentylthiophene. The mixture was stirred overnight at room temperature. After the reaction was complete, the reactants were poured into water. The organic phase was extracted with dichloromethane and anhydrous.

[0021] Drying with Na2SO4 and removing the solvent under reduced pressure. Purification by silica gel column chromatography yields a yellow oily liquid D. The structural formula of compound D is:

[0022]

[0023] (5) Under a nitrogen atmosphere, using anhydrous tetrahydrofuran as the solvent and compound D as the starting material, n-butyllithium was added dropwise at -78°C. After stirring at -78°C for 1-1.5 h, DMF was added, followed by gradual warming to room temperature and stirring overnight. After the reaction was complete, deionized water was added to quench the reaction, the organic phase was extracted with dichloromethane, dried over anhydrous Na2SO4, and the solvent was removed under reduced pressure. The solution was then purified by silica gel column chromatography to obtain an oily compound E. The structural formula of compound E is:

[0024]

[0025] (6) Under a nitrogen atmosphere, N-methylpiperazine, tetrahydrofuran, and alkyllithium reagent were mixed and reacted. After stirring at -78°C for 0.5 h, compound E dissolved in tetrahydrofuran was added, and the reaction was maintained at -78°C for 1 h. Then, the temperature was gradually increased to -20°C, and alkyllithium reagent and organotin halide were added dropwise again. The mixture was stirred overnight at room temperature. After the reaction was completed, deionized water was added to quench the reaction, the organic phase was extracted with petroleum ether, dried over anhydrous Na2SO4, and the solvent was removed under reduced pressure. The solution was then purified by silica gel column chromatography to obtain a yellow solid compound F. The structural formula of compound F is:

[0026]

[0027] (7) Under a nitrogen atmosphere, using anhydrous toluene as a solvent, compounds C and F were mixed and reacted with an organometallic catalyst at 120°C overnight with stirring. After the reaction was complete, deionized water was added to quench the reaction, the organic phase was extracted with dichloromethane, dried over anhydrous Na2SO4, and the solvent was removed under reduced pressure. The mixture was then purified by silica gel chromatography to obtain an oily compound G. The structural formula of compound G is as follows:

[0028]

[0029] (8) Using toluene as a solvent and compound G as a raw material, the terminal unit 3-(dicyanomethylene)indophenone, hexanoic anhydride, and boron trifluoride diethyl ether were added sequentially. The mixture was stirred at room temperature for 15 min. After the reaction was completed, the reaction solution was added dropwise to methanol, and the solid was collected by filtration to obtain a black-green solid compound H, which is the small molecule acceptor with benzothiadiazole selenide as its core.

[0030] Preferably, in step (1), the molar ratio of 4,7-dibromo-2,1,3-benzothiadiazole, trifluoromethanesulfonic anhydride, and nitric acid is 1:3.53:17.65;

[0031] In step (2), the molar ratio of compound A to iron powder is 1:14;

[0032] In step (3), the molar ratio of compound B to selenium dioxide is 1:4; the volume ratio of the mixed solution of anhydrous ethanol and tetrahydrofuran is 4:1.

[0033] In step (4), the molar ratio of cyclopentylthiophene, bromoalkyl, potassium iodide and potassium hydroxide is 1:2.68:0.14:3.28;

[0034] In step (5), the molar ratio of compound D, n-butyllithium, and DMF is 1:0.95:1.5;

[0035] In step (6), the molar ratio of compound E, N-methylpiperazine, alkyllithium and organotin halide is 1:1.5:1.05:1.04;

[0036] In step (7), the molar ratio of compound F to compound C is 1:2.8.

[0037] Preferably, in step (6), the organotin halide is tributyltin chloride and the alkyl lithium is n-butyllithium.

[0038] Preferably, in step (7), the organometallic catalyst added to the reaction is one or more of bis(triphenylphosphine)palladium dichloride, diphenylphosphine ferrocene palladium dichloride, and tetra(triphenylphosphine)palladium, and the molar ratio of compound F to organometallic catalyst is 1:0.1.

[0039] Preferably, in step (8), the molar ratio of compound G, 3-(dicyanomethylene)indoketone, hexanoic anhydride and boron trifluoride diethyl ether is 1:5:7:14.

[0040] The small molecule acceptor with benzothiadiazole and selenium diazole as its core provided by this invention is used as a near-infrared organic optoelectronic material in organic optoelectronic detector devices.

[0041] Therefore, the present invention, employing the above-mentioned small molecule receptor with benzothiadiazole and selenium diazole as its core, and its preparation and application, possesses the following beneficial effects:

[0042] 1. This invention abandons the traditional ADA structure based on Y-series analogs and innovatively designs a conjugated non-fullerene organic small molecule acceptor material with an AD-A'-DA type framework, using a benzothiadiazole-selenodiazole fused heterocyclic structure as the core. The design selects a structure formed by the fusion of strongly electron-withdrawing thiadiazole and selenodiazole units as the central unit. This core structure exhibits extremely strong electron-withdrawing ability, a highly rigid planar framework, and the potential for intermolecular interactions conferred by selenium atoms, resulting in significant advantages such as enhanced near-infrared absorption and charge generation, improved charge transport efficiency and response speed, and reduced energy loss. Furthermore, the synthetic route for the benzothiadiazole-selenodiazole core is relatively mature, and the reaction conditions are controllable, giving the material good potential for practical applications.

[0043] 2. Introducing a cyano group as a terminal group effectively broadens the molecular absorption spectrum and improves the absorption coefficient, while simultaneously lowering the HOMO energy level of small molecule materials. Lowering the HOMO energy level facilitates a more optimized energy level match with the donor material, promotes exciton dissociation, and effectively suppresses dark current generation. By introducing different alkyl chains into the side chains and utilizing their spatial interactions with the main chain, the molecular packing pattern, energy level positions, and solubility can be precisely controlled, which is beneficial for forming an efficient charge transport network and facilitating solution fabrication of high-performance devices. When applied to near-infrared organic photodetectors, it enables efficient near-infrared photogenerated charge generation, separation, and transport, ultimately exhibiting excellent detection performance at the device level, including high specific detectivity, high responsivity, fast response speed, and low dark current density. Attached Figure Description

[0044] Figure 1 This is a synthetic route diagram of Se-CPDT-4F prepared in Example 1 of the present invention;

[0045] Figure 2 The compound (VI) prepared in Example 1 of this invention 1 HNMR spectrum

[0046] Figure 3 The compound (VII) prepared in Example 1 of this invention 1 H NMR spectrum.

[0047] Figure 4 The compound (VIII) prepared in Example 1 of this invention 1 HNMR spectrum.

[0048] Figure 5 The compound (IX) prepared in Example 1 of this invention 1 HNMR spectrum.

[0049] Figure 6 The compound Se-CPDT-4F prepared in Example 1 of this invention 1 H NMR spectrum.

[0050] Figure 7 This is a synthetic route diagram of Se-CPDT-4Cl prepared in Example 2 of the present invention;

[0051] Figure 8 The compound Se-CPDT-4Cl prepared in Example 2 of this invention 1 H NMR spectrum.

[0052] Figure 9 The UV spectra of the compounds Se-CPDT-4F and Se-CPDT-4Cl prepared in this invention.

[0053] Figure 10 CV curves of the compounds Se-CPDT-4F and Se-CPDT-4Cl prepared for this invention. Detailed Implementation

[0054] This invention provides a small molecule receptor with benzothiadiazole and selenidediazole as its core, the molecular structure of which is shown in Formula I:

[0055]

[0056] Wherein, R group is alkyl, and the molecular formula is C m H 2m+1 m is an integer greater than or equal to 1; the X group is a hydrogen group, a halogen group, or a pseudohalogen group.

[0057] Preferably, X is H, F, Cl, Br or CN; and R is 2-ethylethane, 2-butylbutane or 2-hexyldecane.

[0058] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0059] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0060] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. These other embodiments are also covered within the scope of protection of this invention.

[0061] Unless otherwise specified, the "water" used in the following examples is deionized water.

[0062] In the following tests of this invention, proton nuclear magnetic resonance (NMR) spectra were performed on an AVANCE NEO 500MHz superconducting NMR spectrometer from Bruker GmbH, Germany. The solvent used was deuterated chloroform (CDCl3), and the instrument was calibrated with tetramethylsilane (TMS).

[0063] Example 1

[0064] This embodiment provides a small molecule acceptor with a benzothiadiazole-selenodiazole core, designated Se-CPDT-4F, and its synthetic route is as follows: Figure 1 As shown. The specific preparation steps are as follows:

[0065] (1) Synthesis of compound (II):

[0066] At 0°C, trifluoromethanesulfonic anhydride (6.78 g, 24.02 mmol) and nitric acid (7.57 g, 120.08 mmol) were added sequentially to a solution of 4,7-dibromo-2,1,3-benzothiadiazole (2.00 g, 6.80 mmol) in sulfolane (16 mL). After stirring at room temperature for 1 h, the temperature was raised to 90°C and stirred overnight. After the reaction was confirmed to be complete by thin-layer chromatography, the reaction solution was poured into ice water (100 mL), filtered under reduced pressure to collect the crude solid, and purified by recrystallization from anhydrous ethanol to give a yellow solid as compound (II) (2.12 g, yield of this step: 81.16%).

[0067] (2) Synthesis of compound (III):

[0068] Iron powder (4.07 g, 72.92 mmol) was added to a solution of compound (II) (2.00 g, 5.21 mmol) in glacial acetic acid (60 mL) at 0 °C. The mixture was then heated to 45 °C and stirred for 6 h under an argon atmosphere. After confirming the reaction was complete by thin-layer chromatography, the mixture was cooled to room temperature, poured into a 5% sodium hydroxide aqueous solution (100 mL), and the organic phase was extracted with ethyl acetate (3 × 50 mL). The mixture was washed with sodium bicarbonate aqueous solution (3 × 50 mL), dried over anhydrous sodium sulfate, and filtered under reduced pressure to obtain a deep yellow solid (III) (0.73 g, yield of 43.26% in this step). This crude product requires no purification and should be used immediately in the next step.

[0069] (3) Synthesis of compound (IV):

[0070] Compound (III) (0.73 g, 2.25 mmol) was dissolved in a mixture of tetrahydrofuran and ethanol (volume ratio 1:4) at 0 °C. An ethanol solution of selenium dioxide (1.00 g, 9.01 mmol) was slowly added dropwise under an argon atmosphere. The mixture was heated to 75 °C and stirred for 12 h. After the reaction was confirmed to be complete by thin-layer chromatography, the mixture was cooled to room temperature, poured into an aqueous solution (100 mL), and the organic phase was extracted with chloroform (100 mL). The mixture was washed with a saturated saline solution (100 mL) and filtered under reduced pressure to obtain a green solid (IV) (0.28 g, yield of 31.15% in this step).

[0071] (4) Synthesis of compound (VI):

[0072] At 0 °C, 1-bromo-2-butyloctane (11.24 g, 45.10 mmol), potassium iodide (0.39 g, 2.36 mmol), and potassium hydroxide (3.10 g, 55.20 mmol) were added sequentially to a dimethyl sulfoxide (40 mL) solution of cyclopentylthiophene (3.00 g, 16.83 mmol). The mixture was stirred overnight at room temperature. After the reaction was confirmed to be complete by thin-layer chromatography, the reaction solution was poured into ice water (100 mL), and the organic phase was extracted with dichloromethane (3 × 50 mL). The solution was dried over anhydrous Na₂SO₄, and the solvent was removed under reduced pressure. The solution was then purified by rapid column chromatography (eluent: 100% petroleum ether) to obtain a colorless oily liquid (VI) (7.02 g, yield of 81.01% in this step). 1 H NMR see Figure 2 .

[0073] (5) Synthesis of compound (VII):

[0074] Anhydrous tetrahydrofuran (40 mL) was added to compound (VI) (4.00 g, 7.77 mmol) under a nitrogen atmosphere at -78 °C. 2.5 M n-butyllithium (0.47 g, 7.38 mmol) was added dropwise at -78 °C. After stirring at -78 °C for 1 h, N,N-dimethylformamide (0.85 g, 11.65 mmol) was added, followed by gradual warming to room temperature and stirring overnight. After the reaction was confirmed to be complete by thin-layer chromatography, deionized water (100 mL) was added to quench the reaction. The organic phase was extracted with dichloromethane (3 × 50 mL), dried over anhydrous Na₂SO₄, and the solvent was removed under reduced pressure. The crude product was purified by rapid column chromatography (petroleum ether:dichloromethane = 2:1) to give a yellow oily liquid (VII) (3.80 g, yield of 90.10% in this step). 1 H NMR see Figure 3 .

[0075] (6) Synthesis of compound (VIII):

[0076] Under an argon atmosphere at -78°C, N-methylpiperazine (1.27 g, 12.71 mmol) was dissolved in tetrahydrofuran (5 mL), followed by the dropwise addition of n-butyllithium (5.56 mL, 1.6 M) and stirring for 0.5 h. Then, a tetrahydrofuran solution of compound (VII) (4.60 g, 8.47 mmol) was slowly added dropwise while stirring for 1 h. The temperature was slowly raised to -20°C, and n-butyllithium (5.56 mL, 1.6 M) was added again while stirring for 1 h. Finally, tributyltin chloride (2.87 g, 8.81 mmol) was added dropwise, and the mixture was brought to room temperature and stirred overnight. After the reaction was confirmed to be complete by thin-layer chromatography, deionized water (100 mL) was added to quench the reaction. The organic phase was extracted with petroleum ether (3 × 50 mL), washed with saturated brine (3 × 50 mL), dried over anhydrous Na₂SO₄, and the solvent was removed under reduced pressure. The crude product was purified by rapid column chromatography (100% petroleum ether) to obtain a pale yellow oily liquid (VIII) (5.23 g, yield of this step: 74.91%). 1 HNMR see Figure 4 .

[0077] (7) Synthesis of compound (IX):

[0078] Under a nitrogen atmosphere, compound (IV) (0.20 g, 0.50 mmol), compound (VIII) (1.17 g, 1.41 mmol), and bis(triphenylphosphine)palladium dichloride (0.035 g, 0.05 mmol) were mixed in toluene (10 mL), and the mixture was then heated to 1200 °C and stirred overnight. After the reaction was confirmed to be complete by thin-layer chromatography, deionized water (100 mL) was added to quench the reaction. The organic phase was extracted with dichloromethane (3 × 50 mL), washed with saturated brine (3 × 50 mL), dried over anhydrous Na₂SO₄, and the solvent was removed under reduced pressure. The crude product was purified by rapid column chromatography (petroleum ether:dichloromethane = 2:1) to give a brown oily liquid (IX) (0.62 g, yield of 93.48% in this step). 1 HNMR see Figure 5 .

[0079] (8) Synthesis of compound Se-CPDT-4F:

[0080] To a toluene (15 mL) solution of compound (IX) (0.30 g, 0.227 mmol), terminal groups of 5,6-difluoro-3-(dicyanomethylene)indophenone (0.26 g, 1.13 mmol), boron trifluoride diethyl ether (0.45 g, 3.17 mmol), and hexanoic anhydride (0.34 g, 1.59 mmol) were added. The reaction mixture was stirred at room temperature for 15 min. After the reaction was confirmed to be complete by thin-layer chromatography, the reaction mixture was added dropwise to methanol (100 mL), and the solid was collected by filtration. The crude product was purified by rapid column chromatography (petroleum ether: dichloromethane at a ratio of 2:1) to give a blackish-green solid Se-CPDT-4F (315 mg, yield of this step: 79.50%). 1 H NMR see Figure 6 .

[0081] Example 2:

[0082] This embodiment provides a small molecule acceptor with a benzothiadiazole-selenodiazole core, designated Se-CPDT-4Cl, and its synthetic route is as follows: Figure 7 As shown.

[0083] The preparation steps in this embodiment are the same as steps (1)-(7) in Example 1, and will not be repeated here. The only difference is that in step (8), 5,6-dichloro-3-(dicyanomethylene)indophenone (0.30 g, 1.13 mmol), boron trifluoride ether (0.45 g, 3.17 mmol), and hexanoic anhydride (0.34 g, 1.59 mmol) with terminal groups were added to a toluene (15 mL) solution of compound (IX) (0.30 g, 0.227 mmol). The reaction solution was stirred at room temperature for 15 min. After the reaction was detected to be complete by thin-layer chromatography, the reaction solution was added dropwise to methanol (100 mL), and the solid was collected by filtration. The crude product was purified by rapid column chromatography (petroleum ether: dichloromethane at a ratio of 2:1) to obtain a blackish-purple solid.

[0084] Se-CPDT-4Cl (336 mg, yield of this step 81.72%), its 1 H NMR see Figure 8 .

[0085] Example 3

[0086] The compounds prepared in Examples 1 and 2 were dissolved in chloroform at a concentration of 0.01 mg / mL and measured at room temperature. The optical absorption spectra of the thin films were prepared by spin-coating a chloroform solution (15.0 mg / mL, 3000 rpm) onto a quartz plate. Figure 9 The UV-Vis spectra are as follows: The UV-Vis absorption spectra of the solution and the thin film were recorded using a Hitachi U-4100 UV-Vis spectrophotometer. Figure 9As can be seen, the maximum absorption peak of compound Se-CPDT-4F is red-shifted by about 300 nm compared to compound Se-CPDT-4Cl in the thin film absorption spectrum. Compared to Se-CPDT-4F, Se-CPDT-4F has a wider absorption range in the thin film, which helps to improve charge mobility.

[0087] The compounds prepared in Examples 1 and 2 were electrochemically tested on a CHI660D electrochemical workstation using a three-electrode system (glassy carbon electrode as the working electrode, Ag / Ag+ electrode as the reference electrode, and platinum wire as the counter electrode). Cyclic voltammetry (CV) was performed using a nitrogen-saturated solution of 0.1 mol / L tetrabutylammonium hexafluorophosphate in acetonitrile as the electrolyte, with a scan rate of 100 mV / s. Ferrocene-ferrocene salts (Fc / Fc) were used for the measurements. + As an internal standard, its absolute energy compared to vacuum is -4.7 eV. The HOMO and LUMO energy levels of the material are determined according to the equations.

[0088] from Figure 10 The HOMO energy level of compound Se-CPDT-4F can be calculated to be -5.20 eV, and that of compound Se-CPDT-4Cl is -5.24 eV, indicating that it is conducive to exciton dissociation and improves the external quantum efficiency of organic photodetector materials.

[0089] Therefore, this invention constructs a novel AD-A'-DA structured conjugated non-fullerene organic small molecule based on a novel benzothiadiazole-selenidediazole structure as the core design. This novel acceptor molecule differs from Y6-type fused-ring small molecules, requiring fewer synthesis steps and lowering costs while maintaining high energy conversion efficiency and high stability.

[0090] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and does not limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A small molecule receptor with benzothiadiazole-selenodiazole as its core, characterized in that, The small molecule acceptor with benzothiadiazole selenidediazole as its core is an AD-A'-DA structured conjugated non-fullerene organic small molecule, and its molecular structure is shown in Formula I: Wherein, R group is an alkyl group with the molecular formula C m H 2m+1 , where m is an integer greater than or equal to 1; X group is a hydrogen group, a halogen group or a pseudohalogen group.

2. The small molecule receptor with benzothiadiazole-selenodiazole as its core according to claim 1, characterized in that, X is H, F, Cl, Br, or CN.

3. The small molecule receptor with benzothiadiazole-selenodiazole as its core according to claim 2, characterized in that, The R group is 2-ethylethane, 2-butylbutane, or 2-hexyldecane.

4. A method for preparing a small molecule receptor with a benzothiadiazole-selenodiazole core as described in any one of claims 1-3, characterized in that, Using 4,7-dibromo-2,1,3-benzothiadiazole as a starting material, a benzothiadiazole-selenodiazole core was first obtained through nitration, reduction, and cyclization. Then, a cyclopentylthiaphene module substituted with aldehyde and organotin groups was constructed using cyclopentylthiaphene as a starting material. After condensing the benzothiadiazole-selenodiazole core with the cyclopentylthiaphene module, the target compound was obtained by reacting it with the terminal unit 3-(dicyanomethylene)indone and its derivatives.

5. The preparation of the small molecule receptor with benzothiadiazole-selenodiazole as the core according to claim 4, characterized in that, Includes the following steps: (1) Using 4,7-dibromo-2,1,3-benzothiadiazole as a starting material, compound A was obtained by reacting it with nitric acid and trifluoromethanesulfonic anhydride. The structural formula of compound A is: (2) Compound A is reduced with glacial acetic acid and iron powder to obtain compound B. The structural formula of compound B is: (3) Compound B reacts with selenium dioxide in a mixed solution of tetrahydrofuran and ethanol to give compound C. The structural formula of compound C is: (4) Using cyclopentylthiophene as a raw material, bromoalkyl groups, potassium iodide, and potassium hydroxide were added sequentially to react and compound D was obtained. The structural formula of compound D is: (5) Compound D reacts with n-butyllithium and N,N-dimethylformamide to introduce an aldehyde group, yielding compound E. The structural formula of compound E is: (6) Compound E reacts with N-methylpiperazine, alkyllithium, and organotin halide to introduce a tributyltin group, yielding compound F. The structural formula of compound F is: (7) Compound F and compound C undergo a Stille coupling reaction to give compound G. The structural formula of compound G is: (8) Compound G and the end unit are polycondensed by Knoevenagel to obtain compound H, which is a small molecule acceptor with benzothiadiazole and selenidediazole as the core.

6. The preparation of the small molecule receptor with benzothiadiazole-selenodiazole as the core according to claim 5, characterized in that, In step (1), the molar ratio of 4,7-dibromo-2,1,3-benzothiadiazole, trifluoromethanesulfonic anhydride, and nitric acid is 1:3.53:17.65; In step (2), the molar ratio of compound A to iron powder is 1:14; In step (3), the molar ratio of compound B to selenium dioxide is 1:4; the volume ratio of the mixed solution of anhydrous ethanol and tetrahydrofuran is 4:

1. In step (4), the molar ratio of cyclopentylthiophene, bromoalkyl, potassium iodide and potassium hydroxide is 1:2.68:0.14:3.28; In step (5), the molar ratio of compound D, n-butyllithium, and N,N-dimethylformamide is 1:0.95:1.5; In step (6), the molar ratio of compound E, N-methylpiperazine, alkyllithium and organotin halide is 1:1.5:1.05:1.04; In step (7), the molar ratio of compound F to compound C is 1:2.

8. An organometallic catalyst is added to the reaction. The organometallic catalyst is one or more of bis(triphenylphosphine)palladium dichloride, diphenylphosphine ferrocene palladium dichloride, and tetra(triphenylphosphine)palladium. The molar ratio of compound F to organometallic catalyst is 1:0.

1.

7. The preparation of the small molecule receptor with benzothiadiazole-selenodiazole as the core according to claim 5, characterized in that, In step (6), the organotin halide is tributyltin chloride and the alkyl lithium is n-butyllithium.

8. The preparation of the small molecule receptor with benzothiadiazole-selenodiazole as the core according to claim 5, characterized in that, In step (8), the terminal units are 3-(dicyanomethylene)indoketone, hexanoic anhydride, and boron trifluoride diethyl ether, and the molar ratio of compound G, 3-(dicyanomethylene)indoketone, hexanoic anhydride, and boron trifluoride diethyl ether is preferably 1:5:7:

14.

9. The preparation of the small molecule receptor with benzothiadiazole-selenodiazole as the core according to claim 5, characterized in that, Steps (1) to (4) are performed in an argon atmosphere, and steps (5) to (8) are performed in a nitrogen atmosphere.

10. The application of a small molecule receptor with a benzothiadiazole-selenodiazole core as described in any one of claims 1-3, characterized in that, The small molecule acceptor with benzothiadiazole and selenium diazole as its core is used as a near-infrared organic optoelectronic material in organic optoelectronic detector devices.

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