Asymmetric small molecule receptor photovoltaic material and preparation method and application thereof

Abstract

The invention belongs to the technical field of organic solar cell materials, and discloses an asymmetric small molecule receptor photovoltaic material and a preparation method and application thereof. According to the present invention, five kinds of the asymmetric small molecule receptor materials, i.e., IDT-S-4F, IDT-S-4Cl, IDT-S-2F2Cl, IDT-S-2Cl2 F and IDT-2Cl2 F, are synthesized; according to the present invention, the J-V test results show that the asymmetric small molecule receptor PM6: X (X = IDT-S-4F, IDT-S-2F2Cl, IDT-S-2Cl2F) has characteristics of high fill factor and high current density; the Paios test result shows that the acceptor has higher charge carrier mobility, more sensitive photocurrent response speed, better inhibition of bimolecular recombination and trap-assisted recombination, and higher exciton dissociation and charge recombination efficiency. A DFT (Discrete Fourier Transform) result shows that the acceptor material has a smaller dihedral angle, which is beneficial to intermolecular accumulation, so that the material has better carrier mobility. Various tests show that construction of the asymmetric small molecule receptor is a strategy for improving the performance of the device.

Description

Technical Field

[0001] The invention belongs to the technical field of organic solar cell materials, and in particular refers to an asymmetric small molecule acceptor photovoltaic material and a preparation method and application thereof. Background Art

[0002] With the development and utilization of solar energy, organic solar cells (OSCs) have gradually come into the sight of scientific researchers, and OSCs have attracted widespread attention due to their low manufacturing cost, light weight, green solvent processing, and flexible wearability. (Tang Y, Zheng H, Zhou X, et al. N-dopants optimize the utilization of spontaneously formed photocharges in organic solar cells[J]. Energy & Environmental Science, 2023, 16(2): 653-662; Pang B, Liao C, Xu X, et al. Benzo[d]thiazole based wide bandgap donor polymers enable 19.54% efficiency organic solar cells along with desirable batch-to-batch reproducibility and general applicability[J]. Advanced Materials, 2023, 35(21): 2300631.)

[0003] With the exploration of photovoltaic materials in the past decade, the photoelectric conversion efficiency of OSCs has made a qualitative leap, and it has also moved one step closer to commercialization. As researchers have discovered, the device structure of OSCs is basically fixed as ITO / PEDOT:PSS / active layer / PDINN / Ag. The donor material and acceptor material in the active layer are of utmost importance. The matching of the donor and acceptor is more conducive to the dissociation of excitons and the transfer of charges. The commonly used active layer structures are BHJ structure (Sun X, Zhang C, Yao Y, et al. 19.35% Efficient Binary Bulk-Heterojunction Organic Photovoltaic Enabled by Optimizing Bromine-Substituted Self-Assembled Carbazole Based Molecules[J]. Advanced Functional Materials, 2024: 2406060.) and LBL structure (Zhou M, Liao C, Duan Y, et al. 19.10% Efficiency and 80.5% Fill Factor Layer-by-Layer Organic Solar Cells Realized by 4-Bis(2-Thienyl)Pyrrole-2,5-Dione Based Polymer Additives for Inducing Vertical Segregation Morphology[J].Advanced Materials,2023,35(6):2208279.), among which the development of active layer materials has a great influence on the efficiency of devices (Wang J,Xue P,Jiang Y,et al.The principles,design andapplications of fused-ring electron acceptors[J].Nature Reviews Chemistry,2022,6(9):614-634;Gu X,Zhang X,Huang H.Oligomerized Fused-Ring Electron Acceptors for Efficient and Stable Organic Solar Cells[J].Angewandte Chemie,2023,135(46):e202308496;Yi J,Zhang G,Yu H,et al.Advantages,challenges andmolecular design of different material types used in organic solar cells[J].Nature Reviews Materials,2024,9(1):46-62.)。.

[0004] In the early stages of development, fullerene-based derivative materials dominated the OSCs receptor materials. These materials have good conductivity and the prepared active layer has faster charge transfer (Dang MT, Hirsch L, Wantz G. P3HT:PCBM, best seller in polymer photovoltaic research [J]. 2011.). However, fullerene-based derivative materials have defects such as narrow light absorption range, poor band gap regulation, and easy crystallization, which affects the morphology of the prepared active layer. In order to make up for the shortcomings, people have turned their attention to the research and development of other types of small molecule acceptor materials, among which the representative materials are ITIC (Lin Y, Wang J, Zhang ZG, et al. An electron acceptor challenging fullerenes for efficient polymer solar cells [J]. Advanced materials, 2015, 27 (7): 1170-1174.) and Y6 (Yuan J, Zhang Y, Zhou L, et al. Single-junction organic solar cell with over 15% efficiency using fused-ring acceptor with electron-deficient core [J]. Joule, 2019, 3 (4): 1140-1151.). Since the release of Y6, researchers have conducted in-depth research and development on it due to its advantages such as faster transmission rates of electrons, holes and excitons and large electron coupling (Zhang Y, Ji Y, Zhang Y, et al. Recent progress of Y6-derived asymmetric fused ring electron acceptors [J]. Advanced Functional Materials, 2022, 32 (35): 2205115.). Among them, BTP-ec9 and L8BO are two outstanding materials. As derivatives of Y6, BTP-ec9 and L8BO have excellent solubility and can be processed with green solvents, which is consistent with the design concept.The prepared binary device has better active layer morphology, more efficient charge transfer, and less charge recombination, allowing it to achieve a PCE close to 18% (Cui Y, Yao H, Zhang J, et al. Single-junction organic photovoltaic cells with approaching 18% efficiency[J]. Advanced Materials, 2020, 32(19): 1908205; Li C, Zhou J, Song J, et al. Non-fullerene acceptors with branched side chains and improved molecular packingto exceed 18% efficiency in organic solar cells[J]. Nature Energy, 2021, 6(6): 605-613.).

[0005] With the improvement of new materials and new processes, the efficiency of devices with polymer materials as donors and other small molecule materials as acceptors has exceeded 20% (Jiang Y, Sun S, Xu R, et al. Non-fullerene acceptor with asymmetric structure and phenyl-substituted alkyl side chain for 20.2% efficiency organic solar cells[J]. Nature Energy, 2024: 1-12; Bi P, Wang J, Cui Y, et al. Enhancing photon utilization efficiency for high-performance organic photovoltaic cells via regulating phase-transition kinetics[J]. Advanced Materials, 2023, 35(16): 2210865.).

[0006] As researchers further explored, they discovered a series of strategies to improve efficiency. One is to use different additives, which will affect the film formation process of the active layer, and then affect its filling factor and current (Liang Q, Li W, Lu H, et al. Recent advances of solid additives used in organic solar cells: toward efficient and stable solar cells[J]. ACS Applied Energy Materials, 2022, 6(1): 31-50.; McDowell C, Abdelsamie M, Toney MF, et al. Solvent additives: keymorphology-directing agents for solution-processed organic solar cells[J]. Advanced Materials, 2018, 30(33): 1707114.; Xia X, Mei L, He C, et al. Revealing the crystalline packing structure of Y6 in the active layer of organic solar cells: the critical role of solvent additives[J]. Journal of Materials Chemistry A, 2023, 11(40): 21895-21907.).The second is to prepare ternary devices. On the basis of the original binary device, a third component is introduced into the active layer to prepare a ternary device with an active layer of a mixture of two donor materials and one acceptor material or one donor material and two acceptor materials (Jiang Y, Sun S, Xu R, et al. Non-fullerene acceptor with asymmetric structure and phenyl-substituted alkyl side chain for 20.2% efficiency organic solar cells [J]. Nature Energy, 2024: 1-12.; Xu J, Zhu C, Liu Z, et al. Over 19% Efficiency Ternary Organic Solar Cells Enabled by Tuning Charge Behaviors through Quinoxalineimide-based Y-type Acceptors [J]. Materials Today Energy, 2024: 101694.; Ma R, Yan C, Fong PWK, et al. In situ and ex situ investigations on ternary strategy and co-solvent effects towards high-efficiency organic solar cells[J].Energy&Environmental Science,2022,15(6):2479-2488.;Zhan L,Li S,Li Y,et al.Desired open-circuit voltage increase enables efficiencies approaching 19%in symmetric-asymmetric molecule ternaryorganic photovoltaics[J].Joule,2022,6(3):662-675.). The third is the halogenation strategy. Because halogen atoms have strong electronegativity, the introduction of halogen atoms can not only enhance the charge transfer between molecules and the electron-withdrawing ability of the acceptor unit, but also enhance the interaction between molecules.Introducing halogen atoms into acceptor materials has been shown to improve the light-harvesting ability of acceptors, regulate energy levels and intermolecular stacking behavior (Chen H, Zou Y, Liang H, et al. Lowing the energy loss of organic solar cells by molecular packing engineering via multiple molecular conjugation extension [J]. Science China Chemistry, 2022, 65 (7): 1362-1373.; Zhang C, Chang M, Zhang Y, et al. Design of Halogenated Donors for Efficient All-Small-Molecular Organic Solar Cells [J]. ACS Materials Letters, 2024, 6 (5): 1984-1991.; Gu X, Zeng R, Hou Y, et al. Precisely Regulating Intermolecular Interactions and Molecular Packing of Nonfused-Ring Electron Acceptors via Halogen Transposition for High-Performance Organic Solar Cells [J]. Angewandte Chemie, 2024: e202407355.).Finally, the asymmetric small molecule receptor is constructed, which can not only expand the electron delocalization, but also stabilize the conjugated skeleton structure and further enhance the charge transfer effect within the molecule (Wu J, Fu C, Chen B, et al. Isomeric Effect of aπBridge in an IDT-BasedNonfused Electron Photovoltaic Acceptor[J]. Chemistry-A European Journal, 2024, 30(1): e202302624.; Feng F, Wang P, Li Y, et al. Versatileπ-bridges in nonfullereneelectron acceptors of organic solar cells[J]. Materials Chemistry Frontiers, 2023, 7(18): 3855-3878.; Liu W, Zheng X, Ran G, et al. Impact ofπ-bridge unit infully nonfused ring electron acceptor on the photovoltaic performance oforganic solar cells[J]. Chemical Engineering Journal, 2023, 473: 145131.; Wang P, Li Y, Han C, et al. Rationally regulating theπ-bridge of small molecule acceptors for efficient organic solar cells[J]. Journal of Materials Chemistry A, 2022, 10(34): 17808-17816.; Huo L, Hou J. Benzo[1,2-b:4,5-b′]dithiophene-based conjugated polymers: band gap and energy level control and their application in polymer solar cells[J]. Polymer Chemistry, 2011, 2(11): 2453-2461.). In order to reduce the dihedral angle of the material and increase the dipole moment of the material, it is crucial to develop small molecule acceptor materials with new structures. Summary of the invention

[0007] In order to solve the above technical problems, the present invention proposes an asymmetric small molecule acceptor photovoltaic material and a preparation method and application thereof.

[0008] To achieve the above object, the technical solution of the present invention is implemented as follows:

[0009] An asymmetric small molecule acceptor photovoltaic material having a structure as shown in Formula I, Formula II, Formula III, Formula IV or Formula V:

[0010]

[0011] Since the structural characteristics of the material are asymmetric, it may affect the photoelectric properties of the material film, such as electron mobility. When the blended film receptor is illuminated, it will also have a huge impact on the exciton dissociation efficiency, exciton diffusion, charge transfer, etc., thereby affecting the overall performance of the device.

[0012] The preparation method of the above-mentioned asymmetric small molecule acceptor photovoltaic material comprises the following steps:

[0013] (1) reactant 1 and reactant 2 or compound 5 are dissolved in an organic solvent, stirred until completely dissolved, and then argon is bubbled through for 20 minutes to remove air. Then, pyridine is quickly added to the reaction system, and argon is continued to be bubbled through for 10 minutes, followed by an oil bath reaction. After the reaction is complete, the organic solvent is removed by rotary evaporation to obtain a crude product; the product is purified by silica gel column chromatography using CHCl3 / petroleum ether (v / v=3:1) as an eluent, and finally, the product is precipitated with methanol and filtered to obtain compound 3;

[0014] Among them, the structural formula of reactant 1 is The structural formula of reactant 2 is The structural formula of reactant 5

[0015] (2) In an ice-water bath, the excess DMF and phosphorus oxychloride were fully stirred for 30 minutes, and compound 3 was completely dissolved in the organic solvent, and then added to the pre-mixed solution for light-proof reaction. After the reaction was completed, the reaction was quenched, and then extracted with CHCl3 in a separatory funnel, dried over anhydrous magnesium sulfate, and rotary evaporated to obtain a crude product. CHCl3 / petroleum ether (v / v=3:1) was used as the eluent, and the product was purified by silica gel column chromatography, and finally the product was precipitated in methanol and filtered to obtain compound 4;

[0016] The structural formula of compound 3 is

[0017] (3) Compound 4 and reactant 5 or reactant 2 are added to an organic solvent and stirred until completely dissolved, and then argon is passed through the system by bubbling for 20 minutes to remove air, and then pyridine is quickly added to the reaction system, and argon is continued to be passed through for 10 minutes, and then an oil bath reaction is performed. After the reaction is complete, the organic solvent is removed by rotary evaporation to obtain a crude product; CHCl3 / petroleum ether (v / v=3:1) is used as an eluent and the product is purified by silica gel column chromatography, and finally methanol is used for precipitation and suction filtration to obtain the reactant asymmetric small molecule receptor photovoltaic material; wherein the structural formula of compound 4 is

[0018]

[0019] In this preparation process, when the structural formula of reactant 1 is When reactant 5 or reactant 2 cannot be selected simultaneously in step (1) and step (3), an asymmetric small molecule acceptor photovoltaic material is prepared.

[0020] In the above step (1), the molar ratio of reactant 1 to reactant 2 or reactant 5 is 1:1.5.

[0021] In the above step (1), the volume ratio of pyridine to the organic solvent is 1:10-20. For example, the volume ratio of pyridine to the organic solvent is 1:10-15; the volume ratio of pyridine to the organic solvent is 1:15-20; the volume ratio of pyridine to the organic solvent is 1:13-18; the volume ratio of pyridine to the organic solvent is 1:10, 1:13, 1:15, 1:16, 1:18 or 1:20.

[0022] The above organic solvent is chloroform.

[0023] The temperature of the oil bath reaction is 60-70° C. For example, the temperature of the oil bath reaction is 60-65° C.; the temperature of the oil bath reaction is 65-70° C.; the temperature of the oil bath reaction is 62-68° C.; for example, the temperature of the oil bath reaction is 60° C., 62° C., 64° C., 65° C., 66° C., 68° C. or 70° C.

[0024] In the above step (2), the volume ratio of phosphorus oxychloride to DMF is 1:1.4-1.6.

[0025] In the above step (2), phosphorus oxychloride and DMF are first mixed in an ice-water bath for 30 minutes, and the temperature of the light-proof reaction is 60-70° C. For example, the temperature of the light-proof reaction is 60-65° C.; the temperature of the light-proof reaction is 65-70° C.; the temperature of the light-proof reaction is 62-68° C.; for example, the temperature of the light-proof reaction is 60° C., 62° C., 64° C., 65° C., 66° C., 68° C. or 70° C.

[0026] In the above step (3), the molar ratio of compound 4 to reactant 5 or reactant 2 is 1:1.3-1.8.

[0027] In the above step (3), the volume ratio of pyridine to the organic solvent is 1:15-25. For example, the volume ratio of pyridine to the organic solvent is 1:15-20; the volume ratio of pyridine to the organic solvent is 1:20-25; the volume ratio of pyridine to the organic solvent is 1:18-22; the volume ratio of pyridine to the organic solvent is 1:15, 1:17, 1:20, 1:21, 1:22, 1:23, 1:24 or 1:25.

[0028] Application of the above-mentioned asymmetric small molecule acceptor photovoltaic material in the preparation of photovoltaic acceptor material.

[0029] The above-mentioned asymmetric small molecule acceptor photovoltaic material is used in the preparation of binary devices and / or ternary devices.

[0030] The beneficial effects produced by the present invention are:

[0031] (1) This application uses IDT as the core to design and synthesize five asymmetric small molecule receptor materials, IDT-S-4F, IDT-S-2Cl2F, IDT-S-2F2Cl, IDT-S-4Cl, and IDT-2F2Cl. The feasibility of IDT-S-4F, IDT-S-2Cl2F, IDT-S-2F2Cl, and IDT-S-4Cl as receptors was explored through DFT. Through simulation calculations, it was found that these four asymmetric materials have similar and very small dihedral angles (7.9°-8.68°), which is conducive to the stacking of molecules, thereby facilitating the blended membrane to obtain a higher mobility.

[0032] (2) The IDT-based acceptor materials IDT-S-4F, IDT-S-2Cl2F, IDT-S-2F2Cl, IDT-S-4Cl, and IDT-2F2Cl of the present application have good energy levels and wide and strong absorption spectra. It is feasible to use asymmetric small molecule materials based on IDT as the core as photovoltaic acceptor materials. Compared with IDT-2Cl2F, the device based on PM6:X (X=IDT-S-4F / IDT-S-2Cl2F / IDT-S-2F2Cl) has a relatively higher filling factor and current density, which also provides a choice for future asymmetric small molecule acceptor materials as active layer materials for binary and ternary devices.

[0033] (3) The IDT-based asymmetric receptor materials IDT-S-4F, IDT-S-2F2Cl, IDT-S-2Cl2F, IDT-S-4Cl, and IDT-2Cl2F of the present application. It can be obtained through UV-visible absorption spectrum testing that compared with IDT-2F2Cl, the absorption curves of IDT-S-4F, IDT-S-2F2Cl, IDT-S-2Cl2F, and IDT-S-4Cl are significantly red-shifted. When they are mixed with PM6, they can form a wider absorption spectrum and expand the utilization rate of visible light. The energy level of the material can be obtained through electrochemical testing, among which the energy level of IDT-S-4F is (-3.735eV to -5.345eV), the energy level of IDT-S-2Cl2F is (-3.685eV to -5.305eV), the energy level of IDT-S-2F2Cl is (-3.675eV to -5.345eV), and the energy level of IDT-2Cl2F is (-3.685eV to -5.555eV). When constructing devices, appropriate energy level matching is conducive to the dissociation and charge transfer of excitons, reducing recombination, thereby improving the photoelectric conversion efficiency. Through DFT theoretical simulation calculations, it can be seen that several types of asymmetric small molecule receptor materials have small dihedral angles and good planarity, which will make the stacking between the molecules of the mixed film more compact, which is conducive to improving the electron mobility and charge transfer in the mixed film.

[0034] (4) In this application, a series of optimizations are performed on the devices prepared by mixing these four materials with PM6. From the JV test results, it can be seen that among the devices prepared by mixing with PM6, the device efficiency of PM6:IDT-S-4F and PM6:IDT-S-2F2Cl is higher than that of PM6:IDT-S-2Cl2F. In comparison, the filling factors of PM6:IDT-S-4F and PM6:IDT-S-2F2Cl (63.86%, 63.82%) are higher than that of PM6:IDT-S-2Cl2F (59.60%). After a series of optimizations (ratio, additives, annealing, etc.), it can be found that in this application, PM6:IDT-S-4F (filling factor reaches 63.86%, voltage reaches 0.880V, current reaches 21.055mAcm -2 ) and PM6:IDT-S-2F2Cl (fill factor reached 63.82%, voltage reached 0.866V, current reached 20.62mAcm -2) can reach 12.18% and 11.39%, while the efficiency of the device prepared by IDT-S-2Cl2F and PM6 with relatively small dipole moment reaches 10.95%. From the DFT calculation, it can be obtained that the dihedral angles of IDT-S-4F, IDT-S-2Cl2F, and IDT-S-2F2Cl are similar, but the dipole moments of IDT-S-4F and IDT-S-2F2Cl are slightly larger than that of IDT-S-2Cl2F. Therefore, the data in this application show that the improvement of material performance by dipole moment is greater than the performance improvement brought by dihedral angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 Schematic diagram of the synthesis route of the preparation method of IDT-S-4F of the present invention.

[0037] Figure 2 The schematic diagram of the synthesis route of the preparation method of IDT-S-2Cl2F of the present invention is shown in FIG.

[0038] Figure 3 Schematic diagram of the synthesis route of the preparation method of IDT-S-2F2Cl of the present invention.

[0039] Figure 4 The schematic diagram is a synthetic route of the method for preparing IDT-2Cl2F of the present invention.

[0040] Figure 5 The schematic diagram is a synthetic route of the preparation method of IDT-S-4Cl of the present invention.

[0041] Figure 6 IDT-S-4F of the present invention 1 H NMR.

[0042] Figure 7 IDT-S-2Cl2F of the present invention 1 H NMR.

[0043] Figure 8 IDT-S-2F2Cl of the present invention 1 H NMR.

[0044] Fig. 9 IDT-2Cl2F of the present invention 1 H NMR.

[0045] Fig.10 IDT-S-4Cl of the present invention 1 H NMR.

[0046] Fig.11 It is the UV-visible-near infrared absorption spectrum of IDT-S-2Cl2F / IDT-S-2F2Cl / IDT-S-4F / IDT-S-4Cl / IDT-2Cl2F of the present invention.

[0047] Fig.12 The cyclic voltammetry curves of IDT-S-2Cl2F / IDT-S-2F2Cl / IDT-S-4F / IDT-2Cl2F of the present invention and the corresponding energy level schematic diagram; wherein (a) is the cyclic voltammetry curve; (b) is the energy level schematic diagram.

[0048] Fig.13 It is the molecular conformation diagram, electron cloud density distribution diagram and electrostatic potential diagram of IDT-S-2Cl2F / IDT-S-2F2Cl / IDT-S-4F / IDT-S-4Cl of the present invention.

[0049] Fig.14 The JV curve and external quantum efficiency (EQE) curve of the present invention based on PM6:X (X=IDT-S-4F / IDT-S-2Cl2F / IDT-S-2F2Cl / IDT-2Cl2F); wherein (a) is the JV curve; and (b) is the external quantum efficiency (EQE) curve.

[0050] Fig.15 The electrical properties of devices made by mixing IDT-S-4F, IDT-S-2Cl2F, IDT-S-2F2Cl and IDT-2Cl2F with PM6; (a) is J ph -V eff curves; (b) is J sc -P light ; (c) is V oc -P light ; (d) is photo-CELIV curves; (e) is carrier lifetime curves; (f) is TPC results. DETAILED DESCRIPTION

[0051] The technical solution of the present invention will be clearly and completely described below in conjunction with 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 creative work are within the scope of protection of the present invention.

[0052] Unless otherwise specified, the experimental methods used in the following experimental examples are all conventional methods; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0053] The experimental drugs and chemical reagents used in this application are as follows:

[0054]

[0055] Example 1

[0056] The preparation method of the asymmetric small molecule acceptor photovoltaic material shown in Formula I in this embodiment is as follows: Figure 1 As shown, the specific preparation steps are as follows:

[0057] (1) Synthesis of compound 3: Reactant 1 (200 mg, 0.17 mmol) and reactant 2 (58.69 mg, 0.255 mmol) were added to a two-necked flask containing 15 mL of chloroform (CHCl3) and stirred until completely dissolved. Then, argon was bubbled through for 20 min to remove air. Then, 1 mL of pyridine was quickly added to the reaction system and argon was continued to be bubbled through for 10 min. The two-necked flask was then placed in an oil bath at 65°C and the reaction was monitored using a column chromatography plate (TLC). After the reaction was completed, the mixture was cooled to room temperature and the organic solvent was removed by rotary evaporation to obtain a crude product. The product was purified by silica gel column chromatography using chloroform / petroleum ether (v / v=3:1) as the eluent, and finally precipitated with methanol and filtered to obtain compound 3 (143.4 mg, yield 61.45%).

[0058] (2) Synthesis of compound 4: In the following reaction process, the equivalent ratio of phosphorus oxychloride to DMF is 1:1.4, 1:1.5, and 1:1.6.

[0059] a. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (10.4mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (120mg, 0.087mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (102.23mg, yield 84.5%).

[0060] b. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (9.75mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (120mg, 0.087mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (105.61mg, yield 87.3%).

[0061] c. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (9.1mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (120mg, 0.087mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (104.89mg, yield 86.7%).

[0062] (3) Synthesis of compound IDT-S-4F: In the following synthesis process, the molar ratio of reactant 4 to reactant 2 is 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8.

[0063] a. Place reactant 4 (100 mg, 0.07 mmol) and reactant 2 (20.93 mg, 0.091 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise in 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-4F (68.25 mg, yield 60.4%).

[0064] b. Place reactant 4 (100 mg, 0.07 mmol) and reactant 2 (22.54 mg, 0.098 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried in a vacuum drying oven at 65°C overnight. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-4F (69.72 mg, yield 61.7%).

[0065] c. Place reactant 4 (100 mg, 0.07 mmol) and reactant 2 (24.16 mg, 0.105 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-4F (70.41 mg, yield 62.3%).

[0066] d. Place reactant 4 (100 mg, 0.07 mmol) and reactant 2 (25.77 mg, 0.112 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-4F (69.59 mg, yield 61.6%).

[0067] e. Place reactant 4 (100 mg, 0.07 mmol) and reactant 2 (27.38 mg, 0.119 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise in 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-4F (68.82 mg, yield 60.9%).

[0068] f. Place reactant 4 (100 mg, 0.07 mmol) and reactant 2 (28.99 mg, 0.126 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise in 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried in a vacuum drying oven at 65°C overnight. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-4F (67.57 mg, yield 59.8%).

[0069] IDT-S-4F 1 H NMR spectrum Figure 6 As shown:

[0070] 1 H NMR(400MHz,Chloroform-d)δ8.87(s,1H),8.72(s,1H),8.54(dt,J=9.9,6.4Hz,2H),7.76-7.54(m,7H),7.21-7.06 (m,16H),2.95(d,J=6.1Hz,2H),2.58(dq,J=8.2,4.2Hz,8H),1.58(s,11H),1.37-1.24(m,30H),0.90-0.82(m,18H).

[0071] Example 2

[0072] The preparation method of the asymmetric small molecule acceptor photovoltaic material shown in Formula II in this embodiment is as follows: Figure 2 As shown, the specific preparation steps are as follows:

[0073] (1) Synthesis of compound 3: Reactant 1 (200 mg, 0.17 mmol) and reactant 5 (67.08 mg, 0.255 mmol) were added to a two-necked flask containing 15 mL of chloroform (CHCl3) and stirred until completely dissolved. Then, argon was bubbled through for 20 min to remove the air. Then, 1 mL of pyridine was quickly added to the reaction system and argon was continued to be bubbled through for 10 minutes. The two-necked flask was then placed in an oil bath at 65°C and the reaction was monitored using a column chromatography plate (TLC). After the reaction was completed, the mixture was cooled to room temperature and the organic solvent was removed by rotary evaporation to obtain a crude product. The product was purified by silica gel column chromatography using chloroform / petroleum ether (v / v=3:1) as the eluent, and finally precipitated with methanol and filtered to obtain compound 3 (153.7 mg, yield 64.3%).

[0074] (2) Synthesis of compound 4: In the following reaction process, the equivalent ratio of phosphorus oxychloride to DMF is 1:1.4, 1:1.5, and 1:1.6.

[0075] a. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise) inject DMF (10.4mL) into the two-necked flask and stir at low temperature for 30min. Dissolve compound 3 (140mg, 0.099mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform and dry with anhydrous magnesium sulfate, and evaporate the solvent under reduced pressure to obtain a crude product. Use chloroform and petroleum ether as eluents (v / v=3:1) as eluents for column chromatography purification, vacuum rotary evaporation, sedimentation, and suction filtration to obtain compound 4 (112.91mg, yield 79.6%)

[0076] b. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (9.75mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (140mg, 0.099mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (115.4mg, yield 81.3%).

[0077] c. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (9.1mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (140mg, 0.099mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (114.26mg, yield 80.5%).

[0078] (3) Synthesis of compound IDT-S-2Cl2F: In the following synthesis process, the molar ratio of reactant 4 to reactant 2 is 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, and 1:1.8.

[0079] a. Place reactant 4 (110 mg, 0.076 mmol) and reactant 2 (22.73 mg, 0.099 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2Cl2F (74.22 mg, yield 59.3%).

[0080] b. Place reactant 4 (110 mg, 0.076 mmol) and reactant 2 (24.48 mg, 0.106 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2Cl2F (76.85 mg, yield 61.4%).

[0081] c. Place reactant 4 (110 mg, 0.076 mmol) and reactant 2 (26.24 mg, 0.114 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2Cl2F (78.86 mg, yield 63.1%).

[0082] d. Place reactant 4 (110 mg, 0.076 mmol) and reactant 2 (27.84 mg, 0.121 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried in a vacuum drying oven at 65°C overnight. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2Cl2F (77.98 mg, yield 62.3%).

[0083] e. Place reactant 4 (110 mg, 0.076 mmol) and reactant 2 (29.68 mg, 0.129 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise in 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2Cl2F (77.22 mg, yield 61.7%).

[0084] f. Place reactant 4 (110 mg, 0.076 mmol) and reactant 2 (31.47 mg, 0.136 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise in 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2Cl2F (75.61 mg, yield 60.4%).

[0085] IDT-S-2Cl2F 1 H NMR spectrum Figure 7 As shown:

[0086] 1H NMR(400MHz,Chloroform-d)δ8.88(d,J=9.1Hz,1H),8.77-8.71(m,1H),8.58-8.52(m,1H),8.01-7.30(m,8H),7.23-7.05(m,16H) ,2.92(dd,J=29.6,6.0Hz,2H),2.58(q,J=7.5Hz,8H),1.57(d,J=16.2Hz,11H),1.41-1.22(m,30H),0.86(dt,J=12.6,6.3Hz,18H).

[0087] Example 3

[0088] The preparation method of the asymmetric small molecule acceptor photovoltaic material shown in Formula III in this embodiment has a synthetic route as shown in Figure 3 As shown, the specific preparation steps are as follows:

[0089] (1) Synthesis of compound 3: Reactant 1 (200 mg, 0.17 mmol) and reactant 2 (58.69 mg, 0.255 mmol) were added to a two-necked flask containing 15 mL of chloroform (CHCl3) and stirred until completely dissolved. Then, argon was bubbled through for 20 min to remove the air. Then, 1 mL of pyridine was quickly added to the reaction system and argon was continued to be bubbled through for 10 minutes. The two-necked flask was then placed in an oil bath at 65°C and the reaction was monitored using a column chromatography plate (TLC). After the reaction was completed, the mixture was cooled to room temperature and the organic solvent was removed by rotary evaporation to obtain a crude product. The product was purified by silica gel column chromatography using chloroform / petroleum ether (v / v=3:1) as the eluent, and finally precipitated with methanol and filtered to obtain compound 3 (145.68 mg, yield 62.36%).

[0090] (2) Synthesis of compound 4: In the following reaction process, the equivalent ratio of phosphorus oxychloride to DMF is 1:1.4, 1:1.5, and 1:1.6.

[0091] a. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (9.1mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (140mg, 0.1mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (117.21mg, yield 83.6%).

[0092] b. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (9.75mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (140mg, 0.1mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (120.43mg, yield 85.9%).

[0093] c. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (10.4mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (140mg, 0.1mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (118.04mg, yield 84.2%).

[0094] (3) Synthesis of compound IDT-S-2F2Cl: In the following synthesis process, the molar ratios of reactant 4 and reactant 5 are 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, and 1:1.8.

[0095] a. Place reactant 4 (110 mg, 0.078 mmol) and reactant 5 (26.67 mg, 0.101 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2F2Cl (74.91 mg, yield 58.3%).

[0096] b. Place reactant 4 (110 mg, 0.078 mmol) and reactant 5 (28.67 mg, 0.109 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2F2Cl (77.98 mg, yield 60.7%).

[0097] c. Place reactant 4 (110 mg, 0.078 mmol) and reactant 5 (30.77 mg, 0.117 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2F2Cl (82.69 mg, yield 64.36%).

[0098] d. Place reactant 4 (110 mg, 0.078 mmol) and reactant 5 (32.61 mg, 0.124 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2F2Cl (80.55 mg, yield 62.7%).

[0099] e. Place reactant 4 (110 mg, 0.078 mmol) and reactant 5 (34.72 mg, 0.132 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. The reaction progress was monitored by thin layer chromatography (TLC) during the reaction. After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2F2Cl (78.62 mg, yield 61.2%).

[0100] f. Place reactant 4 (110 mg, 0.078 mmol) and reactant 5 (37.09 mg, 0.141 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2F2Cl (76.31 mg, yield 59.4%).

[0101] IDT-S-2F2Cl 1 H NMR spectrum Figure 8 As shown:

[0102] 1 H NMR(400MHz,Chloroform-d)δ8.88(d,J=9.1Hz,1H),8.81-8.48(m,3H),8.01-7.36(m,8H),7.21-7.09(m,16H),2.92 (dd,J=30.8,6.1Hz,2H),2.63-2.53(m,8H),1.58(s,11H),1.37-1.23(m,30H),0.86(td,J=12.7,10.9,4.7Hz,18H).

[0103] Example 4

[0104] The preparation method of the asymmetric small molecule acceptor photovoltaic material shown in Formula IV in this embodiment has a synthetic route as shown in Figure 4 As shown, the specific preparation steps are as follows:

[0105] (1) Synthesis of compound 3: Reactant 1 (200 mg, 0.21 mmol) and reactant 2 (72.5 mg, 0.315 mmol) were added to a two-necked flask containing 15 mL of chloroform (CHCl3) and stirred until completely dissolved. Then, argon was bubbled through for 20 min to remove the air. Then, 1 mL of pyridine was quickly added to the reaction system and argon was continued to be bubbled through for 10 minutes. The two-necked flask was then placed in an oil bath at 65°C and the reaction was monitored using a column chromatography plate (TLC). After the reaction was completed, the mixture was cooled to room temperature and the organic solvent was removed by rotary evaporation to obtain a crude product. The product was purified by silica gel column chromatography using chloroform / petroleum ether (v / v=3:1) as the eluent, and finally precipitated with methanol and filtered to obtain compound 3 (162.23 mg, yield 67.31%).

[0106] (2) Synthesis of compound 4: In the following reaction process, the equivalent ratio of phosphorus oxychloride to DMF is 1:1.4, 1:1.5, and 1:1.6.

[0107] a. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (9.1mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (150mg, 0.13mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform and dry with anhydrous magnesium sulfate, evaporate under reduced pressure to remove the solvent to obtain a crude product, and use chloroform and petroleum ether as eluents (v / v=3:1) as eluents for column chromatography purification, evaporate under reduced pressure, settle, and filter to obtain compound 4 (124.08mg, yield 81.2%).

[0108] b. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (9.75mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (150mg, 0.13mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (128.86mg, yield 84.3%).

[0109] c. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (10.4mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (150mg, 0.13mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (126.22mg, yield 82.6%).

[0110] (3) Synthesis of compound IDT-2Cl2F: In the following synthesis process, the molar ratios of reactant 4 and reactant 5 are 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, and 1:1.8.

[0111] a. Place reactant 4 (110 mg, 0.093 mmol) and reactant 5 (31.82 mg, 0.121 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-2Cl2F (85.51 mg, yield 64.7%).

[0112] b. Place reactant 4 (110 mg, 0.093 mmol) and reactant 5 (34.19 mg, 0.130 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-2Cl2F (86.16 mg, yield 65.2%).

[0113] c. Place reactant 4 (110 mg, 0.093 mmol) and reactant 5 (36.56 mg, 0.139 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. The reaction progress was monitored by thin layer chromatography (TLC) during the reaction. After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-2Cl2F (88.94 mg, yield 67.32%).

[0114] d. Place reactant 4 (110 mg, 0.093 mmol) and reactant 5 (39.19 mg, 0.149 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-2Cl2F (87.48 mg, yield 66.2%).

[0115] e. Place reactant 4 (110 mg, 0.093 mmol) and reactant 5 (41.56 mg, 0.158 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. The reaction progress was monitored by thin layer chromatography (TLC) during the reaction. After the reaction was complete, it was cooled to room temperature and added dropwise in 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-2Cl2F (IDT-2F2Cl) (85.63 mg, yield 64.8%).

[0116] f. Place reactant 4 (110 mg, 0.093 mmol) and reactant 5 (43.93 mg, 0.167 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise in 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-2Cl2F (83.78 mg, yield 63.4%).

[0117] IDT-2Cl2F 1 H NMR spectrum Fig. 9 As shown:

[0118] 1H NMR(400MHz,Chloroform-d)δ8.90(d,J=3.1Hz,1H),8.77(d,J=3.1Hz,1H),7.93(d,J=4.1Hz,1H),7.76-7.71(m,3H),7.65(d, J=34.3Hz,1H),7.18-7.05(m,19H),2.57(q,J=6.3,5.1Hz,8H),1.63-1.58(m,8H),1.34-1.27(m,24H),0.87(t,J=6.6Hz,12H).

[0119] Example 5

[0120] The preparation method of the asymmetric small molecule acceptor photovoltaic material shown in Formula V in this embodiment has a synthetic route as shown in Figure 4 As shown, the specific preparation steps are as follows:

[0121] (1) Synthesis of compound 3: Reactant 1 (200 mg, 0.17 mmol) and reactant 5 (67.08 mg, 0.255 mmol) were added to a two-necked flask containing 15 mL of chloroform (CHCl3) and stirred until completely dissolved. Then, argon was bubbled through for 20 min to remove the air. Then, 1 mL of pyridine was quickly added to the reaction system and argon was continued to be bubbled through for 10 minutes. The two-necked flask was then placed in an oil bath at 65°C and the reaction was monitored using a column chromatography plate (TLC). After the reaction was completed, the mixture was cooled to room temperature and the organic solvent was removed by rotary evaporation to obtain a crude product. The product was purified by silica gel column chromatography using chloroform / petroleum ether (v / v=3:1) as the eluent, and finally precipitated with methanol and filtered to obtain compound 3 (151.4 mg, yield 63.3%).

[0122] (2) Synthesis of compound 4: In the following reaction process, the equivalent ratio of phosphorus oxychloride to DMF is 1:1.4, 1:1.5, and 1:1.6.

[0123] a. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (9.1mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (140mg, 0.099mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (115.42mg, yield 81.3%).

[0124] b. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (9.75mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (140mg, 0.099mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (118.7mg, yield 83.6%).

[0125] c. Use a syringe to inject POCl3 (6.5mL) into a dry 100mL two-necked flask, then use a syringe to slowly (dropwise add) DMF (10.4mL) into the two-necked flask, and stir at low temperature for 30min. Dissolve compound 3 (140mg, 0.099mmol) in chloroform and inject it into the two-necked flask with a syringe. Then move the mixture into an oil bath and stir and reflux at 65°C overnight. After the reaction is completed, quench with distilled water, extract with chloroform, and dry with anhydrous magnesium sulfate. After decompression and rotary evaporation to remove the solvent, the crude product is obtained, and column chromatography is performed with chloroform and petroleum ether as eluents (v / v=3:1) as eluents. Vacuum rotary evaporation, sedimentation, and suction filtration give compound 4 (116.99mg, yield 82.4%).

[0126] (3) Synthesis of compound IDT-S-4Cl: In the following synthesis process, the molar ratios of reactant 4 and reactant 5 are 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, and 1:1.8.

[0127] a. Place reactant 4 (110 mg, 0.076 mmol) and reactant 5 (25.78 mg, 0.098 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2Cl2F (78.91 mg, yield 61.8%).

[0128] b. Place reactant 4 (110 mg, 0.076 mmol) and reactant 5 (27.88 mg, 0.106 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2Cl2F (79.79 mg, yield 62.5%).

[0129] c. Place reactant 4 (110 mg, 0.076 mmol) and reactant 5 (29.98 mg, 0.114 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. The reaction progress was monitored by thin layer chromatography (TLC) during the reaction. After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2Cl2F (81.33 mg, yield 63.7%).

[0130] d. Place reactant 4 (110 mg, 0.076 mmol) and reactant 5 (31.82 mg, 0.121 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried in a vacuum drying oven at 65°C overnight. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2Cl2F (78.26 mg, yield 61.3%).

[0131] e. Place reactant 4 (110 mg, 0.076 mmol) and reactant 5 (33.93 mg, 0.129 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C, and the two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise in 60 mL of HPLC grade methanol for precipitation, and the product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-2Cl2F (77.24 mg, yield 60.5%).

[0132] f. Place reactant 4 (110 mg, 0.076 mmol) and reactant 5 (35.77 mg, 0.136 mmol) in a two-necked flask, add 20 mL of chloroform, and stir until completely dissolved. Then, bubbling argon gas was passed through the reaction system for 15 minutes to exhaust the air therein, and 1 mL of pyridine was quickly added to the reaction system and argon gas was passed through the reaction system for another 15 minutes. The reaction system must be carried out at 65°C. The two-necked flask was transferred to a 65°C oil bath. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC). After the reaction was complete, it was cooled to room temperature and added dropwise to 60 mL of HPLC grade methanol for precipitation. The product was filtered and collected under reduced pressure, and then dried overnight in a vacuum drying oven at 65°C. The product was purified by column chromatography using petroleum ether and chloroform as eluents (v / v=3:1), and then evaporated under reduced pressure, allowed to settle, and filtered to obtain the final product IDT-S-4Cl (75.45 mg, yield 59.1%).

[0133] IDT-S-4Cl 1 H NMR spectrum Fig.10 As shown:

[0134] 1H NMR(400MHz,Chloroform-d)δ8.89(s,1H),8.80-8.72(m,3H),7.93(d,J=14.8Hz,2H),7.77-7.68(m,4H),7.55(s,1H),7.20-7.07 (m,16H),2.96(d,J=6.2Hz,2H),2.62-2.54(m,8H),1.61(dt,J=12.7,7.2Hz,14H),1.26(s,206H),0.86(dd,J=19.9,5.7Hz,99H).

[0135] Implementation effect analysis

[0136] The ultraviolet-visible-near-infrared absorption performance and electrochemical performance of the asymmetric small molecule acceptor photovoltaic material prepared by the present invention are tested and analyzed.

[0137] (1) UV-Vis-NIR absorption properties of IDT-S-4F, IDT-S-4Cl, IDT-S-2Cl2F, IDT-S-2F2Cl and IDT-2Cl2F (IDT-2F2Cl)

[0138] Direct and test process of the film in UV-visible-near infrared absorption performance: UV-visible absorption spectra were recorded on a Hitachi U-3010 UV-visible spectrophotometer. These materials were dissolved in chloroform, stirred and dissolved for 2 hours, and the corresponding chloroform solution was spin-coated on a quartz plate, which was then placed in a test tank for testing.

[0139] The UV-Vis-NIR absorption spectra of IDT-S-4F, IDT-S-4Cl, IDT-S-2Cl2F, IDT-S-2F2Cl and IDT-2Cl2F are shown in Figure 2. Fig.11 As shown. The maximum UV-visible absorption peak of IDT-2Cl2F film is located at 633nm, the maximum UV-visible absorption peak of IDT-S-4F film is located at 760nm, the maximum UV-visible absorption peak of IDT-S-4Cl film is located at 797nm, the maximum UV-visible absorption peak of IDT-S-2Cl2F film is located at 765nm, and the maximum UV-visible absorption peak of IDT-S-2F2Cl film is located at 775nm. Compared with IDT-2Cl2F, the maximum UV-visible absorption peaks of IDT-S-4F, IDT-S-2Cl2F, and IDT-S-2F2Cl all show a red shift, which indicates that with the increase of asymmetry, IDT-S-4Cl, IDT-S-4F, IDT-S-2Cl2F, and IDT-S-2F2Cl have stronger intermolecular interactions in the thin film state than IDT-2Cl2F.

[0140] (2) Electrochemical performance of IDT-S-4F, IDT-S-2Cl2F, IDT-S-2F2Cl, and IDT-2Cl2F

[0141] The electrochemical performance of the prepared acceptor photovoltaic material was tested. The specific process is as follows: Electrochemical cyclic voltammetry measurement was carried out in a traditional three-electrode cell, using a glassy carbon electrode as the working electrode, a platinum wire as the counter electrode, and an Ag / AgNO3 electrode as the reference electrode. The photovoltaic material was evenly coated on the working electrode to form a thin film, and the electrode was placed in tetrabutylammonium hexafluorophosphate (Bu4NPF6) (0.1 mol L -1 ) was used in the acetonitrile solution for testing and the test was carried out using a CHI660-e voltammetry workstation.

[0142] The electrochemical properties of IDT-S-4F, IDT-S-2Cl2F, IDT-S-2F2Cl, and IDT-2Cl2F were determined by cyclic voltammetry. Fig.12 As shown, the initial oxidation potential of IDT-S-4F and the initial reduction potential The initial oxidation potential of IDT-S-2F2Cl is 0.98V and -0.63V respectively. and the initial reduction potential The onset oxidation potentials of IDT-S-2Cl2F are 0.94 V and -0.68 V respectively. and the initial reduction potential The onset oxidation potential of IDT-2Cl2F is 0.98 V and -0.69 V respectively. and the initial reduction potential 1.19V and -0.69V respectively. Calculated according to the empirical equation The HOMO and LUMO levels of IDT-S-4F are -5.68 eV and -4.07 eV, respectively; the HOMO and LUMO levels of IDT-S-2Cl2F are -5.64 eV and -4.02 eV, respectively; the HOMO and LUMO levels of IDT-S-2F2Cl are -5.68 eV and -4.01 eV, respectively; and the HOMO and LUMO levels of IDT-2Cl2F are -5.89 eV and -4.01 eV, respectively.

[0143] (3) Theoretical simulation calculations of IDT-S-4F, IDT-S-4Cl, IDT-S-2Cl2F, and IDT-S-2F2Cl

[0144] Density functional theory (DFT) was used to perform theoretical simulation calculations on the molecular conformation and electron cloud distribution density of IDT-S-4F / IDT-S-4Cl / IDT-S-2Cl2F / IDT-S-2F2Cl. Fig.13 As shown, the electron cloud diagrams on the HOMO and LUMO energy levels of IDT-S-4F, IDT-S-4Cl, IDT-S-2Cl2F, and IDT-S-2F2Cl are mainly distributed on the condensed ring of the IDT central unit. The HOMO and LUMO energy levels of IDT-S-2F2Cl are -5.10eV and -3.28eV, respectively, the HOMO and LUMO energy levels of IDT-S-2Cl2F are -5.10eV and -3.36eV, respectively, the HOMO and LUMO energy levels of IDT-S-4Cl are -5.12eV and -3.37eV, respectively, and the HOMO and LUMO energy levels of IDT-S-4F are -5.08eV and -3.27eV, respectively. This shows that the theoretically calculated frontier orbital energy level results are basically the same as the electrochemical results.

[0145] The dihedral angle between the π bridge and the IDT central unit in IDT-S-2Cl2F is about 8.5°, while the dihedral angle between the π bridge and the IDT central unit in IDT-S-2F2Cl is about 8.14°, the dihedral angle between the π bridge and the IDT central unit in IDT-S-4Cl is about 8.68°, and the dihedral angle between the π bridge and the IDT central unit in IDT-S-4F is 7.9°. The similar dihedral angles indicate that the substitution of the halogen atoms at the terminal group of the IDT small molecule has little effect on its planar flatness, and the electron mobility of the corresponding films is also similar.

[0146] The dipole moments of the four IDT small molecule receptors were observed at the same time, among which the dipole moment of IDT-S-2F2Cl was 9.7479 D, the dipole moment of IDT-S-2C2Fl was 9.3335 D, the dipole moment of IDT-S-4Cl was 9.2459 D, ​​and the dipole moment of IDT-S-4F was 9.7320 D. A larger dipole moment usually leads to a higher dielectric constant, which can reduce the exciton binding energy and reduce the charge recombination loss.

[0147] Application Examples

[0148] A device is prepared by mixing the asymmetric small molecule acceptor photovoltaic material prepared by the present invention with PM6, and the photovoltaic performance and electrochemical performance of the device are tested and analyzed.

[0149] The specific preparation method and test process of the device are as follows: The structure of all OSCs adopts the conventional device structure, that is, ITO / PEDOT:PSS / active layer / PDINN / Ag structure. Pre-patterned ITO glass substrate (sheet resistance = 10Ωsq-1 ) were ultrasonically treated in an ultrasonic water bath with deionized water twice (with and without detergent), acetone, and isopropanol. Before use, these ITOs were dried in a vacuum oven and treated with UV ozone (Jelight Company, USA) for 30 minutes to improve their working function and clearance. The PEDOT:PSS aqueous solution (Baytron P 4083 from HCStarck) was immediately filtered with a 0.45 mm filter and pre-coated on these pre-cleaned ITO glass substrates at 7000 rpm for 30 seconds. The ITO was then heated and dried at 150 °C in air for 20 minutes. The PEDOT:PSS coated ITO substrates were transferred to a N2-filled glove box for further processing. The device was optimized according to the previous optimization process, with a D:A weight ratio of 1:1.2 and a solution concentration of 22 mg / ml. The additives under the optimal conditions were selected. The solution was then stirred for 2 hours for intensive mixing. The mixed solution was spin-coated on the PEDOT:PSS layer at 3400 rpm for 30 seconds, and the annealing temperature and annealing time under the optimal conditions were selected. After cooling to room temperature, a 1.0 mg / mL PDINN methanol solution was deposited on these active layers at 3000 rpm for 30 seconds. -5 The Ag layer (~100 nm) was deposited on an ITO glass substrate placed in a mask under a vacuum of 1.3 Pa. The active area of ​​the OSC is 6.0 mm 2 (3mm×2mm), defined by an optical microscope (Olympus BX51). In order to accurately measure the photocurrent, an area of ​​4.16mm 2 A mask (0.26 mm × 0.16 mm) was used to define the active area of ​​the OSC.

[0150] (1) Photovoltaic performance of devices made from IDT-S-4F, IDT-S-2Cl2F, IDT-S-2F2Cl and IDT-2Cl2F mixed with PM6

[0151] The results are as follows Fig.14 As shown in a, it can be clearly seen that the PCEs of the asymmetric small molecule receptor materials with IDT as the core unit are 12.18%, 10.95% and 11.39%, respectively, and the performance is significantly better than IDT-2Cl2F (5.01%).

[0152] (2) EQE external quantum efficiency of devices made of IDT-S-4F, IDT-S-2Cl2F, IDT-S-2F2Cl and IDT-2Cl2F mixed with PM6. Fig.14As shown in b, through the EQE measurement, it was found that the response value of the device based on PM6:X (X = IDT-S-4F / IDT-S-2Cl2F / IDT-S-2F2Cl) to light is significantly higher than that of the device based on PM6:IDT-2Cl2F, which also shows that as the degree of asymmetry of the small molecule receptor with IDT as the core increases, the device based on it is more sensitive to light. The response value of the mutation of the PM6:IDT-2Cl2F binary device at 650-730nm also corresponds to its absorption peak at 700nm of UV-visible absorption. The performance test data of the binary device are shown in Table 1.

[0153] Table 1PM6: X (X = IDT-S-4F / IDT-S-2Cl2F / IDT-S-2F2Cl / IDT-2Cl2F) binary device test data

[0154]

[0155] It can be clearly seen from Table 1 that the current density has been improved, which also shows that after the introduction of the π bridge, the exciton dissociation and charge collection efficiency of the constructed asymmetric small molecule receptor material in the state of the mixed film have been significantly improved.

[0156] (3) Electrical properties of devices made from IDT-S-4F, IDT-S-2Cl2F, IDT-S-2F2Cl and IDT-2Cl2F mixed with PM6

[0157] The electrical performance of the prepared device was tested. The specific process is as follows: the small molecule receptor in this application is mixed with PM6 under the optimal conditions using the above device preparation steps to prepare the device, and then the device is placed on the Paios test instrument platform, and the positive and negative electrodes are added to the positive and negative electrodes of the battery for electrical performance testing. The electrical performance of the device is as follows: Fig.15 shown.

[0158] Fig.15 a Explanation of the exciton dissociation (P) based on PM6:X (X = IDT-S-4F / IDT-S-2Cl2F / IDT-S-2F2Cl / IDT-2Cl2F) device diss )and charge collection(P coll ) are 94.36% and 74.02%, 91.39% and 70.96%, 94.34% and 68.97%, 84.01% and 56.69% respectively. It can be seen that the exciton dissociation efficiency and charge collection efficiency of the asymmetric small molecule receptor based on IDT are higher than those of IDT-2Cl2F. Fig.15b It can be seen that compared with IDT-2Cl2F (α equals 0.973), the bimolecular recombination of IDT-S-4F / IDT-S-2Cl2F / IDT-S-2F2Cl and PM6 prepared devices (α are 0.998, 0.990, and 0.989, respectively) is better suppressed. Fig.15 c It can be obtained that the n value of the device based on PM6:IDT-2Cl2F is 1.69, which is closer to 2, so its bimolecular recombination is inhibited to a certain extent. The n values ​​of the device based on PM6:X (X=IDT-S-4F / IDT-S-2Cl2F / IDT-S-2F2Cl) are 1.009, 0.941, and 1.007 respectively. Among them, the n values ​​of the devices prepared by IDT-S-4F and IDT-S-2F2Cl and PM6 are closer to 1, which indicates that the trap-assisted recombination in the device is inhibited to a certain extent. The n value of the device prepared by IDT-S-2Cl2F and PM6 is less than 1, so its surface trap-assisted recombination is dominant. Fig.15 d shows the Photo-CELIV curve of the PM6:X (X = IDT-S-4F / IDT-S-2Cl2F / IDT-S-2F2Cl / IDT-2Cl2F) binary device. celiv ) are 1.32×10 -4 cm 2 V -1 s -1 , 1.02×10 -4 cm 2 V -1 s -1 , 9.29×10 -5 cm 2 V -1 s -1 , 4.05×10 -5 cm 2 V -1 s -1 From the data, it can be seen that the charge carrier mobility of the device based on the asymmetric small molecule receptor with IDT as the core is significantly higher than that of IDT-2Cl2F (4.05×10 -5 cm 2 V -1 s -1 )high. Fig.15e It can be seen that the carrier lifetime based on PM6:IDT-2F2Cl is 2.986μs, which is longer than that based on PM6:X (X=IDT-S-4F / IDT-S-2Cl2F / IDT-S-2F2Cl) device (0.769μs, 0.623μs, 1.012μs), but due to its lower carrier mobility, the current density of its device is also at a lower state. Fig.15 f It can be seen that the transient current response of the device based on PM6:X (X=IDT-S-4F / IDT-S-2Cl2F / IDT-S-2F2Cl) is more sensitive than that of the device based on PM6:IDT-2Cl2F, indicating that it has a higher charge mobility.

[0159] In summary, the present invention respectively designs and synthesizes five small molecule receptor materials with IDT as the core, among which the asymmetric small molecules with introduced π bridges include IDT-S-4F, IDT-S-4Cl, IDT-S-2Cl2F, and IDT-S-2F2Cl; the asymmetric small molecules without introduced π bridges include IDT-2Cl2F. Electrochemical tests and calculations show that the HOMO and LUMO energy levels of IDT-S-4F are -5.68eV and -4.07eV, respectively, the HOMO and LUMO energy levels of IDT-S-2Cl2F are -5.64eV and -4.02eV, respectively, the HOMO and LUMO energy levels of IDT-S-2F2Cl are -5.68eV and -4.01eV, respectively, and the HOMO and LUMO energy levels of IDT-2Cl2F are -5.89eV and -4.01eV, respectively. Through DFT, the feasibility of four asymmetric small molecules as receptor materials was explored. Through simulation calculations, it was found that the asymmetric small molecules with the introduction of π bridges have smaller dihedral angles, which is conducive to the stacking of molecules, so that the material has better carrier mobility; by comparing IDT-S-4F, IDT-S-4Cl, IDT-S-2Cl2F, IDT-S-2F2Cl, these four materials all have larger dipole moments, which is conducive to increasing the dielectric constant of the material. Then, after blending IDT-S-4F, IDT-S-2Cl2F, IDT-S-2F2Cl, IDT-2Cl2F small molecules with PM6 to make devices, it was found that the asymmetric small molecules with the introduction of π bridges have higher current density and voltage than the small molecules without the introduction of π bridges. Research has shown that the asymmetric small molecule materials IDT-S-4F, IDT-S-2Cl2F, and IDT-S-2F2Cl based on IDT as the core and introducing π bridges have a wider and stronger spectral absorption range and better energy level matching than the small molecule material IDT-2Cl2F without introducing π bridges. The asymmetric small molecule materials introducing π bridges are feasible as photovoltaic receptor materials, and provide certain ideas for the future development of small molecule receptors.

[0160] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An asymmetric small molecule acceptor photovoltaic material, characterized in that: The asymmetric small molecule acceptor photovoltaic material has any one of the structures shown in Formulas I-V:

2. The method for preparing the asymmetric small molecule acceptor photovoltaic material according to claim 1, characterized in that: Here are the steps: (1) Reactant 1 and reactant 2 or reactant 5 are dissolved in an organic solvent, pyridine is added under the condition of passing argon gas, and then an oil bath reaction is carried out. After the reaction is complete, the solvent is removed, purified, methanol is precipitated, and suction filtered to obtain compound 3; wherein the structural formula of reactant 1 is The structural formula of reactant 2 is The structural formula of reactant 5 (2) Under ice bath conditions, phosphorus oxychloride was dissolved in DMF to obtain a mixed liquid, compound 3 was dissolved in an organic solvent, and then added to the mixed liquid to react in the dark. After the reaction, compound 4 was obtained by extraction, drying, rotary evaporation, purification, methanol precipitation, and suction filtration. The structural formula of compound 3 is (3) Compound 4 and reactant 5 or reactant 2 are added to an organic solvent and stirred to dissolve, argon is passed to remove air, pyridine is added, and then an oil bath reaction is performed. After the reaction is completed, the asymmetric small molecule receptor photovoltaic material is obtained by rotary evaporation, purification, methanol precipitation, and suction filtration; wherein the structural formula of compound 4 is 3. The method for preparing an asymmetric small molecule acceptor photovoltaic material according to claim 2, characterized in that: In the step (1), the molar ratio of reactant 1 to reactant 2 or reactant 5 is 1:1.5; and the volume ratio of pyridine to the organic solvent is 1:10-20.

4. The method for preparing an asymmetric small molecule acceptor photovoltaic material according to claim 3, characterized in that: The organic solvent is chloroform.

5. The method for preparing an asymmetric small molecule acceptor photovoltaic material according to claim 4, characterized in that: The temperature of the oil bath reaction is 60-70°C.

6. The method for preparing an asymmetric small molecule acceptor photovoltaic material according to claim 5, characterized in that: In the step (2), the volume ratio of phosphorus oxychloride to DMF is 1:1.4-1.

6.

7. The method for preparing an asymmetric small molecule acceptor photovoltaic material according to claim 6, characterized in that: The temperature of the light-shielded reaction in step (2) is 60-70°C.

8. The method for preparing an asymmetric small molecule acceptor photovoltaic material according to claim 7, characterized in that: In the step (3), the molar ratio of compound 4 to reactant 5 or reactant 2 is 1:1.3-1.8; the volume ratio of pyridine to organic solvent is 1:15-25.

9. Use of the asymmetric small molecule acceptor photovoltaic material according to claim 1 in the preparation of photovoltaic acceptor materials.

10. Use of the asymmetric small molecule acceptor photovoltaic material according to claim 1 in the preparation of binary and / or ternary devices.

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