An endo-linear alkyl-based non-fullerene small molecule acceptor material of type A-DA' D-A, and a preparation method and application thereof

Abstract

The application provides an A-DA'D-A type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl and a preparation method and application thereof. The A-DA'D-A type non-fullerene small molecule acceptor material based on the inner straight-chain alkyl has the structure shown in the following formula I. In the application, the inner alkyl chain of the A-DA'D-A type non-fullerene small molecule acceptor is a straight-chain alkyl structure, the accumulation structure and the degree of disorder between donor molecules or acceptor molecules in the active layer are adjusted, the light-emitting performance of the material and the open-circuit voltage in the device performance are improved, the voltage loss in the organic solar cell is reduced, and the photovoltaic performance of the organic solar device is finally improved.

Description

Technical Field

[0001] This invention belongs to the field of molecular technology, specifically relating to an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group, its preparation method, and its application. Background Technology

[0002] Due to the strong designability of non-fullerene acceptor materials, the performance of organic solar cells has rapidly improved in recent years, with current photoelectric conversion efficiencies exceeding 20%. Commonly used high-efficiency materials include ITIC, Y6, and L8-BO. ​​Developing even more efficient organic photovoltaic materials through structural modification of these materials to further improve the performance of organic solar cells has become a goal for many researchers (L. Zhu, M. Zhang, G. Zhou, Z. Wang, W. Zhong, J. Zhuang, Z. Zhou, X. Gao, L. Kan, B. Hao, F. Han, R. Zeng, X. Xue, S. Xu, H. Jing, B. Xiao, H. Zhu, Y. Zhang, F. Li u, Joule, 2024, 10.1016 / j.joule.2024.08.001;Y.Jiang, S.Sun, R.Xu, F.Liu, X.Miao, G.Ran, K.Liu, Y.Yi, W.Zhang, X.Zhu, Nat.Energy, 2024, 9, 975-986;Y.Sun, L.Wang, C.Guo, J.Xiao, C.Liu, C.Chen, W.Xia, Z.Gan, J.Cheng, J.Zhou, Z.Chen, J.Zhou, D. Liu,T.Wang,W.Li,J.Am.Chem.Soc.,2024,146,12011-12019;J.Yuan,Y.Zhang,L.Zhou,G.Zhang,H.Yip,T.Lau,X.Lu,C.Zhu, H.Peng,PAJohnson,M.Leclerc,Y.Cao,J.Ulanski,Y.Li,Y.Zou,Joule,2019,3,1140-1151;Y.Lin,J.Wang,Z.Zhang,H.Bai,Y. Li, D. Zhu, X. Zhan, Adv. Mater., 2015, 27, 1170-1174; L. Zhu, M. Zhang, J. Xu, C. Li, J. Yan, G. Zhou, W. Zhong, T. Hao, J. Song, X. Xue, Z. Zhou, R. Zeng, H. Zhu, C. Chen, RCI MacKenzie, Y. Zou, J. Nelson, Y. Zhang, Y. Sun, F. Liu, Nat. Mater., 2022, 21, 656-663).

[0003] Adjusting the structure of molecular side chains is a commonly used molecular modification method. The size of the molecular side chains has a significant impact on changes in properties such as molecular packing, disorder, and microstructure in the active layer. For example, the organic solar cells based on L8-BO acceptors reported in the literature have larger side chains linked to the β-position of the bisthiophene moiety compared to those based on classical Y6. Therefore, using L8-BO with larger side chains allows for better molecular packing properties of the acceptor molecule in the donor-acceptor blend, resulting in a power conversion efficiency exceeding 19% for D18:L8-BO-based organic solar cells, while the power conversion efficiency of D18:Y6-based organic solar cells is 18.2% (L.Zhu, M.Zhang, J.Xu, C.Li, J.Yan, G.Zhou, W.Zhong, T.Hao, J.Song, X.Xue, Z.Zhou, R.Zeng, H.Zhu, C.Chen, RCIMacKenzie, Y.Zou, J.Nelson, Y.Zhang, Y.Sun, F.Liu, Nat. Mater., 2022, 21). 656-663; J. Yuan, Y. Zhang, L. Zhou, G. Zhang, H. Yip, T. Lau, X. Lu, C. Zhu, H. Peng, PA Johnson, M. Lec lerc,Y.Cao,J.Ulanski,Y.Li,Y.Zou,Joule,2019,3,1140-1151;J.Wang,D.Qian,F.Dong,H.Wu,H. Pan, S. Liang, H. Wu, X. Feng, W. Li, M. Wang, Z. Tang, Z. Ma, Chem. Eng. J., 2023, 465, 142909; Y. Chen, R. Ma, T. Liu, Y. Xiao, HK Kim, J. Zhang, C. Ma, H. Sun, F. Bai, X. Guo, K. S. Wong, X. Lu, H. Yan, Adv. Energy Mater., 2021, 11, 2003777; H. Wang, S. Wu, D. Yang, X. Yu, S. Yang, P. Ding, P. Yan, Z. Ma, J. Zhang, Z. Ge, Sci. China Chem., 2024, 67, 2686-2693).Similarly, for ternary organic solar cells, the use of L8-BO, an acceptor with a larger side chain, showed improved performance. Organic solar cells based on PM6:D18:L8-BO had a conversion efficiency of 19.6%, while those based on PM6:D18:Y6 had a conversion efficiency of only 17.7% (L.Zhu, M.Zhang, J.Xu, C.Li, J.Yan, G.Zhou, W.Zhong, T.Hao, J.Song, X.Xue, Z.Zhou, R.Zeng, H.Zhu, C.Chen, RCIMacKenzie, Y.Zou, J.Nelson, Y.Zhang, Y.Sun, F.Liu, Nat. Mater., 2022, 21, 656-663).

[0004] Therefore, based on side-chain engineering modification methods, novel A-DA'DA type non-fullerene small molecule acceptor materials are designed to improve the luminescence performance and open-circuit voltage of the materials and devices, thereby reducing voltage loss in organic solar cells. This is of great significance for improving the photovoltaic performance of organic solar devices. Therefore, this invention is proposed. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group, its preparation method, and its applications. This invention uses a straight-chain alkyl group as the inner alkyl chain of the A-DA'DA type non-fullerene small molecule acceptor, thereby adjusting the stacking structure and disorder of the acceptor or acceptor molecules in the active layer. This improves the luminescence performance of the material and the open-circuit voltage in the device performance, reduces voltage loss in organic solar cells, and ultimately enhances the photovoltaic performance of organic solar devices.

[0006] The technical solution of the present invention is as follows:

[0007] A non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group has the structure shown in Formula I:

[0008]

[0009] In Equation I,

[0010] R is C6~C 12 Straight-chain alkyl groups;

[0011] X is S, O, or Se;

[0012] A is an electron-withdrawing group containing an active α-hydrogen.

[0013] According to a preferred embodiment of the present invention, A is selected from one of the following structures:

[0014]

[0015] in,

[0016] R1 is C1~C 30 Alkyl group, R2 is C1 to C2. 30 Alkyl groups.

[0017] According to the present invention, the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups has the structure shown in Formula I-1:

[0018]

[0019] According to the present invention, the preparation method of the above-mentioned A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups includes the following steps:

[0020] (1) In N,N-dimethylformamide, under the action of potassium carbonate, compound 1 and compound R-Br react to give compound 2;

[0021]

[0022] In compound 1, substituent X is the same as X in formula I; in compound R-Br, substituent R is the same as R in formula I;

[0023] (2) Phosphorus oxychloride and N,N-dimethylformamide were stirred and reacted at 0-5℃, and then a chloroform solution of compound 2 was added to react and compound 3 was obtained.

[0024]

[0025] (3) In chloroform, under the action of pyridine, compound 3 and compound containing A unit react to obtain A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl;

[0026] The compound containing unit A is selected from one of the following compounds:

[0027]

[0028] According to a preferred embodiment of the present invention, the volume ratio of N,N-dimethylformamide to the mass ratio of compound 1 in step (1) is 30-100 mL: 1 g.

[0029] According to a preferred embodiment of the present invention, the molar ratio of potassium carbonate to compound 1 in step (1) is 5-20:1.

[0030] According to a preferred embodiment of the present invention, the molar ratio of compound R-Br to compound 1 in step (1) is 3-5:1.

[0031] According to a preferred embodiment of the present invention, the temperature of the reaction in step (1) is 70-90°C, and the reaction time is 10-15 h; the reaction is carried out under a protective gas, which is argon or nitrogen.

[0032] According to a preferred embodiment of the present invention, in step (1), the post-treatment steps of the reaction solution obtained from the reaction are as follows: water is added to the obtained reaction solution, wherein the ratio of the volume of water added to the molar number of compound 1 is 300-500 mL: 1 mmol; then dichloromethane is used for extraction, and after the solvent is removed from the obtained organic phase, a crude product is obtained. The obtained crude product is purified by silica gel column chromatography to obtain compound 2, with dichloromethane: n-hexane = 1:4, v / v as the eluent.

[0033] According to a preferred embodiment of the present invention, the volume ratio of N,N-dimethylformamide to the mass ratio of phosphorus oxychloride in step (2) is 0.5-1 mL:1 g.

[0034] According to a preferred embodiment of the present invention, in step (2), the reaction time of phosphorus oxychloride and N,N-dimethylformamide is 1-2 hours.

[0035] According to a preferred embodiment of the present invention, the concentration of the chloroform solution of compound 2 in step (2) is 10-20 mg / mL; the molar ratio of phosphorus oxychloride to compound 2 is 55-70:1; the chloroform solution of compound 2 is added at room temperature, where room temperature has a meaning known in the art and refers to 25±5℃.

[0036] According to a preferred embodiment of the present invention, in step (2), the reaction temperature after adding compound 2 is 60-70°C and the reaction time is 10-12 h; the reaction is carried out under a protective gas, which is argon or nitrogen.

[0037] According to a preferred embodiment of the present invention, in step (2), the post-treatment steps of the reaction solution obtained from the reaction are as follows: dichloromethane and water are added to the obtained reaction solution for extraction, the solvent is removed from the obtained organic phase, and the crude product is purified by silica gel column chromatography to obtain compound 3, with dichloromethane: n-hexane = 1:1, v / v as the eluent.

[0038] According to a preferred embodiment of the present invention, the volume ratio of chloroform to the mass ratio of compound 3 in step (3) is 50-100 mL: 1 g.

[0039] According to a preferred embodiment of the present invention, the molar ratio of pyridine to compound 3 in step (3) is 10-20:1.

[0040] According to a preferred embodiment of the present invention, the molar ratio of the compound containing unit A to compound 3 in step (3) is 2-4:1.

[0041] According to a preferred embodiment of the present invention, the temperature of the reaction in step (3) is 65-75°C and the reaction time is 8-15 h; the reaction is carried out under a protective gas, which is argon or nitrogen.

[0042] According to a preferred embodiment of the present invention, in step (3), the post-processing steps of the reaction solution obtained from the reaction are as follows: the solvent is removed from the obtained reaction solution, and the crude product obtained is purified by silica gel column chromatography, with dichloromethane:n-hexane = 1.5:1, v / v as the eluent.

[0043] According to the present invention, the above-mentioned A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups is used as an active layer electron acceptor material for light-harvesting in the preparation of organic solar cells.

[0044] The preparation route of the A-DA'DA type non-fullerene small molecule acceptor material based on the inner straight-chain alkyl group of the present invention is as follows:

[0045]

[0046] In the above formula, the substituents R, X, and A are as described above.

[0047] The technical features and beneficial effects of this invention are as follows:

[0048] 1. The inner straight-chain alkyl A-DA'DA type non-fullerene small molecules synthesized in this invention can be processed by solution method, are soluble in organic solvents such as chloroform and chlorobenzene, and have good film-forming properties.

[0049] 2. The inner straight-chain alkyl A-DA'DA type non-fullerene small molecules synthesized in this invention have good light absorption and suitable electronic energy levels, making them suitable for use as electron acceptor materials in organic solar cells, and exhibiting high photoelectric conversion efficiency in organic solar cells.

[0050] 3. This invention discloses an A-DA'DA type non-fullerene small molecule acceptor based on an inner straight-chain alkyl group, and designs and synthesizes a series of novel A-DA'DA type non-fullerene small molecule acceptors with good solubility and thermal stability by changing the electron-withdrawing end groups. By changing the structure of the inner straight-chain alkyl group and the end groups of different lengths in the molecular structure, and combining them with specific outer alkyl chains, the packing density between small molecule acceptors can be adjusted, optimizing the intermolecular aggregation structure and the luminescence performance of the material. In addition, it is also beneficial to adjust the energy level of the material, improve the photoluminescence quantum yield of the molecule, and thus reduce the nonradiative energy loss of the material. Due to their large conjugated structure, these molecules have strong intramolecular charge transport effects and intermolecular packing effects. The material of this invention has strong light absorption capacity, high electron mobility, and suitable electronic energy levels, making it suitable as an electron acceptor material for the fabrication of organic solar cells. Attached Figure Description

[0051] Figure 1 The UV-Vis absorption spectrum of the A-DA'DA type nonfullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 1;

[0052] Figure 2 The UV-Vis absorption spectrum of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 2;

[0053] Figure 3 The UV-Vis absorption spectrum of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 3;

[0054] Figure 4 The UV-Vis absorption spectrum of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 4;

[0055] Figure 5 Cyclic voltammetry curves of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 1;

[0056] Figure 6 Cyclic voltammetry curves of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 2;

[0057] Figure 7 Cyclic voltammetry curves of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 3;

[0058] Figure 8Cyclic voltammetry curves of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 4;

[0059] Figure 9 JV curve of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 1 when applied to organic solar cells;

[0060] Figure 10 JV curve of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 2 when applied to organic solar cells;

[0061] Figure 11 JV curve of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 3 when applied to organic solar cells;

[0062] Figure 12 The JV curve of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared in Example 4 when applied to organic solar cells.

[0063] Figure 13 The JV curve of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups prepared for Comparative Example 1 when applied to organic solar cells.

[0064] Figure 14 The JV curve of the A-DA'DA type non-fullerene small molecule acceptor material based on internally branched alkyl groups prepared for Comparative Example 2 when applied to organic solar cells. Detailed Implementation

[0065] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0066] Example 1

[0067] The synthetic route for an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group is shown below:

[0068]

[0069] The synthesis steps are as follows:

[0070] Step 1) Synthesize compound 2

[0071] Under argon protection, compound 1 (500 mg, 0.645 mmol) was added to a 100 mL two-necked round-bottom flask, followed by n-hexane bromo (426 mg, 2.58 mmol), K₂CO₃ (890 mg, 6.45 mmol), and anhydrous DMF (30 mL). The reaction was carried out at 80 °C for 12 h under Ar₂ protection. After the reaction was completed, 250 mL of water was added to the reaction solution for rapid cooling and extraction. The organic phase was extracted with 200 mL of dichloromethane and collected. The solvent was removed from the obtained organic phase by rotary evaporation to obtain the crude product, which was further purified by silica gel column chromatography (eluent: dichloromethane:n-hexane = 1:4, v / v) to give compound 2, 498 mg, as a red solid, with a yield of 82%.

[0072] Step 2) Synthesize compound 3

[0073] Add 5 g of POCl3 to a 100 mL two-necked flask and purge with argon three times. Then place the reaction flask in an ice-water bath (0 °C) and add 4 mL of DMF dropwise (1 drop / s) under Ar2, stirring at 0 °C for 1 h. Then place the two-necked flask at room temperature and dissolve compound 2 (498 mg, 0.529 mmol) in 35 mL of CHCl3, adding it to the two-necked flask at room temperature. Then place the reaction flask in an oil bath at 65 °C and react at 65 °C for 10 h. After the reaction is complete, cool naturally to room temperature, add dichloromethane (200 mL) and water (250 mL) to the resulting reaction solution for extraction, collect the organic phase, remove the solvent by rotary evaporation to obtain the crude product, and further purify by silica gel column chromatography (eluent: dichloromethane: n-hexane = 1:1, v / v) to obtain compound 3, 454 mg, yield: 86%.

[0074] Step 3) Synthesize compound 4

[0075] Compound 3 (454 mg, 0.455 mmol), IC-F terminal group (310 mg, 1.365 mmol), and CHCl3 (30 mL) were added to a 100 mL two-necked round-bottom flask, and the mixture was purged with argon three times. Under Ar2 atmosphere, 489 mg of pyridine was added, and the reaction was carried out at 70 °C for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography (eluent: dichloromethane: n-hexane = 1.5:1, v / v) to obtain compound 4, which is an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group, denoted as BO-C6.

[0076] The NMR data for product compound 4 are as follows:

[0077] 1H NMR (400MHz, CDCl3): δ (ppm) 8.74 (s, 2H), 8.43 (dd, 2H), 7.58 (t, 2H), 4.68 (m, 4H), 2.92 (d ,4H),2.09(m,6H),1.49(m,8H),1.39(m,12H),1.24(m,24H),0.95(t,6H),0.85(dt,12H);

[0078] 13 C NMR (101MHz, CDCl3): δ (ppm) 185.93, 158.02, 153.44, 152.69, 147.06, 14 5.22,137.16,136.40,134.54,134.24,138.62,132.25,130.41,119.72,1 14.82,114.41,113.41,112.18,111.89,68.99,51.30,39.76,34.65,33.4 7,33.23,31.83,31.64,31.39,29.61,28.90,26.62,22.99,22.65,14.07.

[0079] Example 2

[0080] The synthetic route for an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group is shown below:

[0081]

[0082] The synthesis steps are as follows:

[0083] Step 1) Synthesize compound 2

[0084] Under argon protection, compound 1 (500 mg, 0.645 mmol) was added to a 100 mL two-necked round-bottom flask, followed by bromooctane (498 mg, 2.58 mmol), K₂CO₃ (890 mg, 6.45 mmol), and anhydrous DMF (30 mL). The reaction was carried out at 80 °C for 12 h under Ar₂ protection. After the reaction was completed, 250 mL of water was added to the reaction solution for rapid cooling and extraction. The organic phase was extracted with 200 mL of dichloromethane and collected. The solvent was removed from the obtained organic phase by rotary evaporation to obtain the crude product, which was further purified by silica gel column chromatography (eluent: dichloromethane: n-hexane = 1:4, v / v) to give compound 2, 541 mg, a red solid, with a yield of 84%.

[0085] Step 2) Synthesize compound 3

[0086] Add 5 g of POCl3 to a 100 mL two-necked flask and purge with argon three times. Then place the reaction flask in an ice-water bath (0 °C) and add 4 mL of DMF dropwise (1 drop / s) under Ar2, stirring at 0 °C for 1 h. Then place the two-necked flask at room temperature and dissolve compound 2 (541 mg, 0.542 mmol) in 35 mL of CHCl3, adding it to the two-necked flask at room temperature. Then place the reaction flask in an oil bath at 65 °C and react at 65 °C for 10 h. After the reaction is complete, cool naturally to room temperature, add dichloromethane (200 mL) and water (250 mL) to the resulting reaction solution for extraction, collect the organic phase, remove the solvent by rotary evaporation to obtain the crude product, and further purify by silica gel column chromatography (eluent: dichloromethane: n-hexane = 1:1, v / v) to obtain compound 3, 463 mg, yield: 81%.

[0087] Step 3) Synthesize compound 4

[0088] Compound 3 (463 mg, 0.438 mmol), the IC-F terminal group (298 mg, 1.314 mmol), and CHCl3 (30 mL) were added to a 100 mL two-necked round-bottom flask, and the mixture was purged with argon three times. Under Ar2 atmosphere, 489 mg of pyridine was added, and the reaction was carried out at 70 °C for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography (eluent: dichloromethane:n-hexane = 1.5:1, v / v) to obtain compound 4, which is an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group, denoted as BO-C8.

[0089] The NMR data for product compound 4 are as follows:

[0090] 1 H NMR (400MHz, CDCl3): δ (ppm) 8.76 (s, 2H), 8.45 (dd, 2H), 7.59 (t, 2H), 4.68 (m, 4H), 2.92 ( d,4H),2.10(m,4H),1.96(m,2H),1.49(m,8H),1.39(m,12H),1.24(m,32H),0.85(m,18H);

[0091] 13C NMR (101MHz, CDCl3): δ (ppm) 185.97, 157.91, 153.51, 152.94, 147.09, 145. 19,137.16,134.62,134.29,133.63,132.32,130.48,119.72,114.84,114. 67,114.47,113.43,112.82,112.17,69.00,51.36,39.78,34.67,33.47,33 .22,31.83,31.62,29.61,29.31,28.89,26.65,26.64,22.99,22.66,14.11.

[0092] Example 3

[0093] The synthetic route for an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group is shown below:

[0094]

[0095] The synthesis steps are as follows:

[0096] Step 1) Synthesize compound 2

[0097] Under argon protection, compound 1 (500 mg, 0.645 mmol) was added to a 100 mL two-necked round-bottom flask, followed by bromodecane (570 mg, 2.58 mmol), K₂CO₃ (890 mg, 6.45 mmol), and anhydrous DMF (30 mL). The reaction was carried out at 80 °C for 12 h under Ar₂ protection. After the reaction was completed, 250 mL of water was added to the reaction solution for rapid cooling and extraction. The organic phase was extracted with 200 mL of dichloromethane and collected. The obtained organic phase was removed by rotary evaporation to obtain the crude product, which was further purified by silica gel column chromatography (eluent: dichloromethane: n-hexane = 1:4, v / v) to give compound 2, 545 mg, as a red solid, with a yield of 80%.

[0098] Step 2) Synthesize compound 3

[0099] Add 5 g of POCl3 to a 100 mL two-necked flask and purge with argon three times. Then place the reaction flask in an ice-water bath (0 °C) and add 4 mL of DMF dropwise (1 drop / s) under Ar2, stirring at 0 °C for 1 h. Then place the two-necked flask at room temperature and dissolve compound 2 (545 mg, 0.516 mmol) in 35 mL of CHCl3, adding it to the two-necked flask at room temperature. Then place the reaction flask in an oil bath at 65 °C and react at 65 °C for 10 h. After the reaction is complete, cool naturally to room temperature, add dichloromethane (200 mL) and water (250 mL) to the resulting reaction solution for extraction, collect the organic phase, remove the solvent by rotary evaporation to obtain the crude product, and further purify by silica gel column chromatography (eluent: dichloromethane: n-hexane = 1:1, v / v) to obtain compound 3, 476 mg, yield: 83%.

[0100] Step 3) Synthesize compound 4

[0101] Compound 3 (476 mg, 0.428 mmol), IC-F terminal group (291 mg, 1.285 mmol), and CHCl3 (30 mL) were added to a 100 mL two-necked round-bottom flask, and the mixture was purged with argon three times. Under Ar2 atmosphere, 489 mg of pyridine was added, and the reaction was carried out at 70 °C for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography (eluent: dichloromethane:n-hexane = 1.5:1, v / v) to obtain compound 4, which is an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group, denoted as BO-C10.

[0102] The NMR data for product compound 4 are as follows:

[0103] 1 H NMR (400MHz, CDCl3): δ (ppm) 8.71 (s, 2H), 8.42 (dd, 2H), 7.56 (t, 2H), 4.66 (m, 4H), 2.89 ( d,4H),2.12(m,4H),1.94(m,2H),1.52(m,8H),1.36(m,12H),1.24(m,40H),0.85(m,18H);

[0104] 13C NMR (101MHz, CDCl3): δ (ppm) 185.82, 157.75, 155.44, 153.40, 152.99, 152.86, 147.02, 145.21,137.11,136.37,134.48,134.16,133.60,132.20,130.41,119.66,114.80,114 .63,114.44,113.36,112.09,111.19,69.07,51.39,39.74,34.60,33.46,33.21,31.97,31.84,31.72,29.76,29.66,29.61,29.44,28.89,27.02,26.65,22.99,22.69,14.11.

[0105] Example 4

[0106] The synthetic route for an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group is shown below:

[0107]

[0108] The synthesis steps are as follows:

[0109] Step 1) Synthesize compound 2

[0110] Under argon protection, compound 1 (500 mg, 0.645 mmol) was added to a 100 mL two-necked round-bottom flask, followed by bromododecane (643 mg, 2.58 mmol), K₂CO₃ (890 mg, 6.45 mmol), and anhydrous DMF (30 mL). The reaction was carried out at 80 °C for 12 h under Ar₂ protection. After the reaction was completed, 250 mL of water was added to the reaction solution for rapid cooling and extraction. The organic phase was extracted with 200 mL of dichloromethane and collected. The solvent was removed from the obtained organic phase by rotary evaporation to obtain the crude product, which was further purified by silica gel column chromatography (eluent: dichloromethane: n-hexane = 1:4, v / v) to give compound 2, 580 mg, as a red solid, with a yield of 81%.

[0111] Step 2) Synthesize compound 3

[0112] Add 5 g of POCl3 to a 100 mL two-necked flask and purge with argon three times. Then place the reaction flask in an ice-water bath (0 °C) and add 4 mL of DMF dropwise (1 drop / s) under Ar2, stirring at 0 °C for 1 h. Then place the two-necked flask at room temperature and dissolve compound 2 (580 mg, 0.522 mmol) in 35 mL of CHCl3, adding it to the two-necked flask at room temperature. Then place the reaction flask in an oil bath at 65 °C and react at 65 °C for 10 h. After the reaction is complete, allow it to cool naturally to room temperature, add dichloromethane (200 mL) and water (250 mL) to the resulting reaction solution for extraction, collect the organic phase, remove the solvent by rotary evaporation to obtain the crude product, and further purify by silica gel column chromatography (eluent: dichloromethane: n-hexane = 1:1, v / v) to obtain compound 3, 481 mg, yield: 83%.

[0113] Step 3) Synthesize compound 4

[0114] Compound 3 (481 mg, 0.412 mmol), IC-F terminal group (280 mg, 1.236 mmol), and CHCl3 (30 mL) were added to a 100 mL two-necked round-bottom flask, and the mixture was purged with argon three times. Under Ar2 atmosphere, 489 mg of pyridine was added, and the reaction was carried out at 70 °C for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography (eluent: dichloromethane:n-hexane = 1.5:1, v / v) to obtain compound 4, which is an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group, denoted as BO-C12.

[0115] The NMR data of the product are as follows:

[0116] 1 H NMR (400MHz, CDCl3): δ (ppm) 8.75 (s, 2H), 8.45 (dd, 2H), 7.59 (t, 2H), 4.67 (m, 4H), 2.91 ( d,4H),2.10(m,4H),1.94(m,2H),1.48(m,8H),1.36(m,12H),1.22(m,48H),0.84(m,18H);

[0117] 13C NMR (101MHz, CDCl3): δ (ppm) 185.84, 157.80, 155.59, 155.47, 153.38, 153.00, 152.89, 152.86,147.04,145.17,137.13,136.38,134.53,134.26,133.61,132.28,130.43,119 .74,114.82,114.45,113.39,112.13,111.94,69.07,51.40,39.75,34.61,33.47,33.22,31.92,31.67,29.81,29.73,29.62,29.42,28.89,26.98,26.65,22.99,22.67,14.12.

[0118] Comparative Example 1

[0119] The synthetic route for an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group is shown below:

[0120]

[0121] The synthesis steps are as follows:

[0122] Step 1) Synthesize compound 2

[0123] Under argon protection, compound 1 (500 mg, 0.669 mmol) was added to a 100 mL two-necked round-bottom flask, followed by n-bromodecane (592 mg, 2.68 mmol), K₂CO₃ (923 mg, 6.69 mmol), and anhydrous DMF (30 mL). The reaction was carried out at 80 °C for 12 h under Ar₂ protection. After the reaction was completed, 250 mL of water was added to the reaction solution for rapid cooling and extraction. The organic phase was extracted with 200 mL of dichloromethane and collected. The solvent was removed from the obtained organic phase by rotary evaporation to obtain the crude product, which was further purified by silica gel column chromatography (eluent: dichloromethane:n-hexane = 1:4, v / v) to give compound 2, 571 mg, as a red solid, with a yield of 83%.

[0124] Step 2) Synthesize compound 3

[0125] Add 5 g of POCl3 to a 100 mL two-necked flask and purge with argon three times. Then place the reaction flask in an ice-water bath (0 °C) and add 4 mL of DMF dropwise (1 drop / s) under Ar2, stirring at 0 °C for 1 h. Then place the two-necked flask at room temperature and dissolve compound 2 (571 mg, 0.555 mmol) in 35 mL of CHCl3, adding it to the two-necked flask at room temperature. Then place the reaction flask in an oil bath at 65 °C and react at 65 °C for 10 h. After the reaction is complete, cool naturally to room temperature, add dichloromethane (200 mL) and water (250 mL) to the resulting reaction solution for extraction, collect the organic phase, remove the solvent by rotary evaporation to obtain the crude product, and further purify by silica gel column chromatography (eluent: dichloromethane: n-hexane = 1:1, v / v) to obtain compound 3, 493 mg, yield: 82%.

[0126] Step 3) Synthesize compound 4

[0127] Compound 3 (493 mg, 0.455 mmol), IC-F terminal group (309 mg, 1.365 mmol), and CHCl3 (30 mL) were added to a 100 mL two-necked round-bottom flask, and the mixture was purged with argon three times. Under Ar2 atmosphere, 489 mg of pyridine was added, and the reaction was carried out at 70 °C for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography (eluent: dichloromethane:n-hexane = 1.5:1, v / v) to obtain compound 4, which is an A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group, with the molecule name Y6-C10.

[0128] The NMR data of the product are as follows:

[0129] 1 H NMR (400MHz, CDCl3): δ (ppm) 8.77 (s, 2H), 8.46 (t, 2H), 7.60 (t, 2H), 4.68 (m, 4H), 3.00 (m, 4H), 2 .09-1.99(m,4H),1.84-1.72(m,4H),1.50-1.39(m,8H),1.38-1.12(m,52H),0.92-0.78(m,12H);

[0130] 13C NMR (101MHz, CDCl3): δ (ppm) 185.61,157.37,155.59,155.47,153.31,152.65,152.38,1 47.00,145.28,137.25,136.41,134.66,134.54,133.71,132.54,130.32,119.47,114.23 ,114.15,113.31,112.10,111.88,69.70,66.73,36.92,36.34,31.94,31.92,29.79,29.71,29.66,29.64,29.58,29.52,29.37,29.29,28.41,22.71,22.67,21.01,14.14,14.07.

[0131] Comparative Example 2

[0132] The synthetic route for an A-DA'DA type non-fullerene small molecule acceptor material based on internally branched alkyl groups is shown below:

[0133]

[0134] The synthesis steps are as follows:

[0135] Step 1) Synthesize compound 2

[0136] Under argon protection, compound 1 (500 mg, 0.645 mmol) was added to a 100 mL two-necked round-bottom flask, followed by 3-(bromomethyl)heptane (498 mg, 2.58 mmol), K₂CO₃ (890 mg, 6.45 mmol), and anhydrous DMF (30 mL). The reaction was carried out at 80 °C for 12 h under Ar₂ protection. After the reaction was completed, 250 mL of water was added to the reaction solution for rapid cooling and extraction. The organic phase was extracted with 200 mL of dichloromethane and collected. The solvent was removed from the obtained organic phase by rotary evaporation to obtain the crude product, which was further purified by silica gel column chromatography (eluent: dichloromethane: n-hexane = 1:4, v / v) to give compound 2, 503 mg, as a red solid, with a yield of 78%.

[0137] Step 2) Synthesize compound 3

[0138] Add 5g of POCl3 to a 100mL two-necked flask and purge with argon three times. Then place the reaction flask in an ice-water bath (0℃), add 4mL of DMF dropwise (1 drop / s) under Ar2, and stir at 0℃ for 1h. Then place the two-necked flask at room temperature, dissolve compound 2 (503mg, 0.503mmol) in 35mL of CHCl3, and inject it into the two-necked flask at room temperature. Then place the reaction flask in an oil bath at 65℃ and react at 65℃ for 10h. After the reaction is complete, cool naturally to room temperature, add dichloromethane (200mL) and water (250mL) to the obtained reaction solution for extraction, collect the organic phase, remove the solvent by rotary evaporation to obtain the crude product, and further purify by silica gel column chromatography (eluent: dichloromethane:n-hexane = 1:1, v / v) to obtain compound 3, 425mg, yield: 80%.

[0139] Step 3) Synthesize compound 4

[0140] Compound 3 (425 mg, 0.402 mmol), IC-F terminal group (277 mg, 1.206 mmol), and CHCl3 (30 mL) were added to a 100 mL two-necked round-bottom flask, and the mixture was purged with argon three times. Under Ar2 atmosphere, 489 mg of pyridine was added, and the reaction was carried out at 70 °C for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was purified by silica gel column chromatography (eluent: dichloromethane:n-hexane = 1.5:1, v / v) to obtain compound 4, which is an A-DA'DA type non-fullerene small molecule acceptor material based on an inner-branched alkyl group, namely L8-BO.

[0141] The NMR data of the product are as follows:

[0142] 1 H NMR (400MHz, CDCl3): δ (ppm) 9.15 (s, 2H), 8.59-8.55 (m, 2H), 7.73-7.69 (t, 2H), 4.79-4.77 (d, 4H), 3.19-3.18 (d, 4 H),2.09-2.08(m,4H),1.47-1.23(m,36H),1.06-1.01(m,12H),0.88-0.82(m,12H),0.77-0.76(t,6H),0.67(t,6H);

[0143] 13C NMR (101MHz, CDCl3): δ (ppm) 185.02, 157.95, 155.14, 152.51, 146.54, 144.29, 136.62, 135.61, 134.71, 134.60, 133.52, 133.01, 132 .85,129.65,119.02,114.10,113.73,113.54,112.56,111.55,111.30,67.69,54.66,39.38,39.03,33.73,32.56,32.31,30.80,104 28.60,27.82,26.62,25.56,22.25,21.97,21.62,13.05,13.03,12.71,9.24.

[0144] Experimental Example 1

[0145] The A-DA'DA type non-fullerene small molecule acceptor materials based on inner straight-chain alkyl groups prepared in Examples 1-4 were tested as follows:

[0146] 1. Ultraviolet-Visible Absorption Spectroscopy Test:

[0147] The tests were conducted on an Agilent Technologies Cary series UV-Vis-NIR spectrophotometer. The absorption spectrum of the solution was obtained by using chloroform as the solvent and preparing a 10 μg / mL solution of small molecule acceptor material. The absorption sample of the film was obtained by spin-coating a 15 mg / mL chloroform solution of small molecule acceptor material onto a quartz plate at 3000 rpm for 30 s.

[0148] The UV-Vis absorption spectra of A-DA'DA type non-fullerene small molecule acceptor materials prepared in Examples 1-4 are shown below. Figure 1-4 As shown, by Figure 1-4 It can be seen that the prepared A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups exhibits strong absorption in the 550-850 nm range, and the thin-film absorption shows a significant red shift compared to solution absorption, indicating strong intermolecular interactions and aggregation. In the UV-Vis absorption spectra, the maximum absorption peaks of BO-C6, BO-C8, BO-C10, and BO-C12 are located at 781 nm, 783 nm, 786 nm, and 774 nm, respectively. The BO-C10 acceptor material exhibits a more red-shifted absorption, increasing the light absorption range and thus improving the short-circuit current, thereby enhancing the photovoltaic performance of organic solar cell devices.

[0149] 2. The energy levels of the material were determined by electrochemical cyclic voltammetry:

[0150] On the Zahner-Ennium IM6 electrochemical workstation, a glassy carbon disk was used as the working electrode, a Pt wire as the counter electrode, and an Ag / Ag electrode. + The electrode was used as a reference electrode and tested in a 0.1 mol / L tetrabutylammonium hexafluorophosphate (Bu4NPF6) acetonitrile solution at a scan rate of 50 mV / s.

[0151] The cyclic voltammetry curves of the A-DA'DA type non-fullerene small molecule acceptor materials based on inner straight-chain alkyl groups prepared in Examples 1-4 are shown below. Figure 5-8 As shown, the formula HOMO = -(E ox +4.73)(eV) and LUMO=-(E re +4.73)(eV) can be used to calculate the HOMO and LUMO energy levels of the acceptor material. For example... Figure 5 As shown, the initial oxidation potential of the small molecule receptor material prepared in Example 1 It is 1.07V vs Ag / Ag + Initial reduction potential Is it -0.87V vs Ag / Ag? + The calculated HOMO and LUMO levels of BO-C6 are -5.80 eV and -3.86 eV, respectively; Figure 6 As shown, the initial oxidation potential of the small molecule receptor material prepared in Example 2 It is 1.07V vs Ag / Ag + Initial reduction potential Is it -0.86V vs Ag / Ag? + The calculated HOMO and LUMO levels of BO-C8 are -5.80 eV and -3.87 eV, respectively; Figure 7 As shown, the initial oxidation potential of the small molecule receptor material prepared in Example 3 It's 1.06V vs Ag / Ag + Initial reduction potential It is -0.86Vvs Ag / Ag + The calculated HOMO and LUMO energy levels of BO-C10 are -5.79 eV and -3.87 eV, respectively; Figure 8 As shown, the initial oxidation potential of the small molecule receptor material prepared in Example 4 It's 1.05V vs Ag / Ag + Initial reduction potential Is it -0.85V vs Ag / Ag? + The calculated HOMO and LUMO energy levels of BO-C12 are -5.78 eV and -3.88 eV, respectively, which can be matched with efficient polymer donors.

[0152] Experimental Example 2

[0153] The A-DA'DA type non-fullerene small molecule acceptor materials prepared in Examples 1-4 and Comparative Examples 1-2 were used to prepare solar photovoltaic devices, and their performance was tested. The preparation method of the solar photovoltaic devices is as follows:

[0154] Commercially purchased indium tin oxide (ITO) glass was first cleaned with detergent, then ultrasonically cleaned sequentially with water, deionized water, acetone, and isopropanol, and dried. Next, a 25 nm thick anode buffer layer, PEDOT:PSS, was spin-coated onto the ITO. A chloroform blend solution of polymer donor D18 and A-DA'DA type non-fullerene small molecule acceptor material (weight ratio 1:1.3) (with an A-DA'DA type non-fullerene small molecule acceptor concentration of 10.35 mg / mL in the blend solution) was spin-coated onto the PEDOT:PSS layer to form the active layer of the device (100 nm thick). This was then annealed for 30 seconds using CS2 as a solvent. A 15 nm thick cathode buffer layer, PFN-Br, was then spin-coated onto the active layer. Finally, a 100 nm thick layer of metallic silver was deposited on the PFN-Br as the anode of the photovoltaic device. The effective area of ​​each cell in the active layer of the photovoltaic device is 0.052 cm². -2 .

[0155] An SS-F5-3A (Enli Technology CO., Ltd.) xenon lamp with an AM1.5 filter was used as a simulated solar light source at 100mW / cm². -2 The photovoltaic performance of the device was tested under light intensity, which was calibrated using a standard monocrystalline silicon solar cell; the JV curve was measured using a Keithley 2450.

[0156] The structure of the polymer donor D18 used in this invention is as follows:

[0157]

[0158] Figure 9 The JV curve of BO-C6, an A-DA'DA type non-fullerene small molecule acceptor based on an inner straight-chain alkyl group prepared in Example 1, when applied to an organic solar cell. Figure 9 As shown, the measured short-circuit current J of the device sc 26.7 mA cm -1 Open circuit voltage V oc It has a voltage of 0.902V, a fill factor of 80.7%, and a power conversion efficiency (PCE) of 19.5%.

[0159] Figure 10The JV curve of BO-C8, a non-fullerene small molecule acceptor based on an inner straight-chain alkyl group prepared in Example 2, when applied to an organic solar cell. Figure 10 As shown, the measured short-circuit current J of the device sc 26.9 mAcm -1 Open circuit voltage V oc It has a voltage of 0.911V, a fill factor of 80.6%, and a power conversion efficiency (PCE) of 19.8%.

[0160] Figure 11 The JV curve of BO-C10, a non-fullerene small molecule acceptor based on an inner straight-chain alkyl group prepared in Example 3, when applied to an organic solar cell. Figure 11 As shown, the measured short-circuit current J of the device sc 27.2 mAcm -1 Open circuit voltage V oc It has a voltage of 0.926V, a fill factor of 80.5%, and a power conversion efficiency (PCE) of 20.3%.

[0161] Figure 12 The JV curve of BO-C12, a non-fullerene small molecule acceptor based on an inner straight-chain alkyl group prepared in Example 4, when applied to an organic solar cell. Figure 12 As shown, the measured short-circuit current J of the device sc 26.1 mAcm -1 Open circuit voltage V oc It has a voltage of 0.931V, a fill factor of 78.9%, and a power conversion efficiency (PCE) of 19.2%.

[0162] Figure 13 The JV curve of Y6-C10, a non-fullerene small molecule acceptor based on an inner straight-chain alkyl group prepared for Comparative Example 1, when applied to an organic solar cell. Figure 13 As shown, the measured short-circuit current J of the device sc 26.8 mAcm -1 Open circuit voltage V oc It has a voltage of 0.894V, a fill factor of 76.5%, and a power conversion efficiency (PCE) of 18.4%.

[0163] Figure 14 The JV curve of L8-BO, a non-fullerene small molecule acceptor based on an inner-branched alkyl group and prepared for Comparative Example 2, when applied to an organic solar cell. Figure 14 As shown, the measured short-circuit current J of the device sc 26.9 mAcm -1 Open circuit voltage Voc It has a voltage of 0.911V, a fill factor of 78.2%, and a power conversion efficiency (PCE) of 19.2%.

[0164] The four acceptor materials, BO-C6, BO-C8, BO-C10, and BO-C12, exhibited photoelectric conversion efficiencies of 19.5%, 19.8%, 20.3%, and 19.2%, respectively. Among them, BO-C10 showed the best results due to its highest fill factor (FF), short-circuit current, and relatively high open-circuit voltage. Furthermore, compared with the comparative examples Y6-C10 and L8-BO, BO-C10 exhibited higher open-circuit voltage, short-circuit current, and fill factor (FF), thus demonstrating better photovoltaic performance.

[0165] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group, characterized in that, It has the structure shown in Equation I: I In Equation I, R is C 10 Straight-chain alkyl groups; X is S; A is an electron-withdrawing group containing an active α-hydrogen, selected from one of the following structures: in, R1 is C1~C 30 Alkyl group, R2 is C1~C 30 Alkyl groups.

2. The A-DA'DA type non-fullerene small molecule acceptor material based on an inner straight-chain alkyl group according to claim 1, characterized in that, The A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups has the structure shown in Formula I-1: I-1。 3. The method for preparing the A-DA'DA type non-fullerene small molecule acceptor material based on the inner straight-chain alkyl group as described in claim 1, comprising the following steps: (1) In N,N-dimethylformamide, under the action of potassium carbonate, compound 1 and compound R-Br react to give compound 2; In compound 1, substituent X is the same as X in formula I; in compound R-Br, substituent R is the same as R in formula I; (2) Phosphorus oxychloride and N,N-dimethylformamide were stirred and reacted at 0-5℃, and then a chloroform solution of compound 2 was added to react and compound 3 was obtained. (3) In chloroform, under the action of pyridine, compound 3 and compound containing unit A react to obtain A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups; The compound containing unit A is selected from one of the following compounds: 。 4. The method for preparing A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups according to claim 3, characterized in that, The volume ratio of N,N-dimethylformamide to the mass ratio of compound 1 in step (1) is 30-100 mL: 1 g; the molar ratio of potassium carbonate to compound 1 is 5-20: 1; and the molar ratio of compound R-Br to compound 1 is 3-5:

1.

5. The method for preparing A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups according to claim 3, characterized in that, The reaction temperature in step (1) is 70-90℃, and the reaction time is 10-15h; the reaction is carried out under a protective gas, which is argon or nitrogen. In step (1), the post-processing steps of the reaction solution are as follows: water is added to the reaction solution, and the ratio of the volume of water added to the molar number of compound 1 is 300-500 mL: 1 mmol; then dichloromethane is used for extraction, and after removing the solvent from the organic phase, a crude product is obtained. The crude product is purified by silica gel column chromatography to obtain compound 2, with dichloromethane: n-hexane = 1:4, v / v as the eluent.

6. The method for preparing A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups according to claim 3, characterized in that, The volume ratio of N,N-dimethylformamide to phosphorus oxychloride in step (2) is 0.5-1 mL:1 g; the stirring reaction time of phosphorus oxychloride and N,N-dimethylformamide is 1-2 h. In step (2), the concentration of the chloroform solution of compound 2 is 10-20 mg / mL; the molar ratio of phosphorus oxychloride to compound 2 is 55-70:1; the chloroform solution of compound 2 is added at room temperature, the reaction temperature after adding compound 2 is 60-70℃, and the reaction time is 10-12 h; the reaction is carried out under a protective gas, which is argon or nitrogen. The post-processing steps of the reaction solution obtained in step (2) are as follows: add dichloromethane and water to the obtained reaction solution for extraction, remove the solvent from the obtained organic phase, and purify the crude product by silica gel column chromatography to obtain compound 3. The eluent is dichloromethane: n-hexane = 1:1, v / v.

7. The method for preparing A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups according to claim 3, characterized in that, In step (3), the volume ratio of chloroform to the mass of compound 3 is 50-100 mL: 1 g; the molar ratio of pyridine to compound 3 is 10-20: 1; and the molar ratio of the compound containing unit A to compound 3 is 2-4:

1.

8. The method for preparing A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups according to claim 3, characterized in that, The reaction temperature in step (3) is 65-75℃, and the reaction time is 8-15h; the reaction is carried out under a protective gas, which is argon or nitrogen. In step (3), the post-processing steps of the reaction solution are as follows: the solvent is removed from the reaction solution, and the crude product is purified by silica gel column chromatography with dichloromethane:n-hexane = 1.5:1, v / v as the eluent.

9. The application of the A-DA'DA type non-fullerene small molecule acceptor material based on inner straight-chain alkyl groups as described in claim 1, characterized in that, It is used as an active layer electron acceptor material for light trapping in the fabrication of organic solar cells.

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