Fused-ring monomers based on benzodithiophene, their polymers, preparation methods, and applications

Abstract

This invention belongs to the field of photovoltaic materials technology, and discloses a fused-ring monomer based on benzodithiophene, its polymer, preparation method, and applications. The fused-ring monomer based on benzodithiophene provided by this invention can be used as a polymerization monomer to further prepare donor polymers. The polymer provided by this invention has a conjugated six-membered ring structure and can be used as a donor material in the fabrication of organic photovoltaic devices. The solar cell prepared using the benzodithiophene-based polymer of this invention exhibits good stability and high photoelectric conversion efficiency, reaching 18.13%.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic materials technology, and specifically relates to fused ring monomers based on benzodithiophene, their polymers, preparation methods, and applications. Background Technology

[0002] Organic solar cells (OSCs) have a sandwich structure, where the active layer material is sandwiched between an interface layer material and an electrode material. The active layer material is responsible for photon absorption and charge transport, and is the core of the OSC. Active layer materials can be classified into donor materials and acceptor materials according to their basic properties and roles in the photoelectric conversion process. Polymer donor materials are DA copolymers formed by alternating copolymerization of electron-rich and electron-deficient monomers. Currently, there are relatively few high-performance polymer donor materials, making it difficult to meet the requirements for matching with non-fullerene acceptor materials. Furthermore, the resulting OSC devices suffer from poor stability and low photoelectric conversion efficiency. Therefore, there is an urgent need to develop high-performance polymer donor materials to obtain OSC devices with good stability and high photoelectric conversion efficiency. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a fused-ring monomer based on benzodithiophene, its polymer, preparation method and application. The polymer is prepared using a fused-ring monomer based on benzodithiophene, and the prepared polymer can be used as a donor material to prepare organic photovoltaic devices with good stability and high photoelectric conversion efficiency, with a photoelectric conversion efficiency of up to 18.13%.

[0004] A first aspect of the present invention is to provide a fused-ring monomer based on benzodithiophene.

[0005] Specifically, a fused-ring monomer based on benzodithiophene has the following general structural formula:

[0006]

[0007] Wherein, C is one of the following structures:

[0008]

[0009] R is H or any alkyl chain of C1-C24; Y is one of O, S, N, and Se; X1, X2, X3, X4, X5, X6, X7, X8, X9, X 10 X 11 X 12 The components are independently selected from one of H, F, Cl, CN, and COORO, where R0 is any alkyl chain from C1 to C24. It is understood that the dashed lines in the structural formula represent chemical bond connections.

[0010] The benzodithiophene-based fused-ring monomer provided by this invention has two main structural characteristics: first, it possesses imide or other strong electron-withdrawing functional groups; second, it has a relatively large fused aromatic ring. These two structural characteristics result in strong π-π packing and numerous weak interactions within the molecule. Using the benzodithiophene-based fused-ring monomer to prepare polymers results in polymers with good morphological stability and the formation of nanofiber-like structures in thin films, which is beneficial for improving the thermal stability of the materials. The obtained polymers can be used as donor materials in the fabrication of stable organic photovoltaic devices with high photoelectric conversion efficiency.

[0011] Preferably, the benzodithiophene-based fused-ring monomer has one of the following structures:

[0012]

[0013] A second aspect of the present invention is to provide a method for preparing a fused-ring monomer based on benzodithiophene.

[0014] Specifically, the preparation method of fused-ring monomers based on benzodithiophene includes the following steps:

[0015] The benzodithiophene-based fused-ring monomer was obtained by Stille coupling reaction using dibromo-substituted compounds and tributyltin-substituted compounds.

[0016] Preferably, the Stille coupling reaction uses a palladium catalyst.

[0017] Preferably, the palladium catalyst is one of tris(dibenzylacetone)palladium, tetratriphenylphosphine palladium, or palladium acetate.

[0018] Preferably, the synthetic reaction formula for the fused-ring monomer based on benzodithiophene is as follows:

[0019]

[0020] A third aspect of the present invention is to provide a polymer, wherein the raw materials for preparing the polymer include the benzodithiophene-based fused-ring monomer described in this invention.

[0021] Preferably, the polymer has the following general structural formula:

[0022]

[0023] L1 has one of the following structures:

[0024]

[0025] D has one of the following structures:

[0026]

[0027] X1, X2, X3, X4, X5, X6, X7, X8, X9, X 10 X 11 X 12 Independently selected from one of H, F, Cl, CN, and COOR, where R is; Y is one of O, S, N, and Se; R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 R 12 Independently selected from any alkyl chain of H or C1-C24; n is a positive integer.

[0028] Preferably, the polymer has one of the following structures:

[0029]

[0030] A fourth aspect of the present invention is to provide a method for preparing the polymer described herein, comprising the following steps:

[0031] The polymer is obtained by reacting the benzodithiophene-based fused-ring monomer with Stille coupling reaction in an inert atmosphere.

[0032] Preferably, the Stille coupling reaction uses a palladium catalyst.

[0033] Preferably, the palladium catalyst is one of tris(dibenzylacetone)palladium, tetratriphenylphosphine palladium, or palladium acetate.

[0034] Preferably, the synthesis reaction formula of the polymer is as follows:

[0035]

[0036] The method for preparing the polymer includes the following steps:

[0037] The benzodithiophene-based fused-ring monomer (compound 1) was brominated with NBS to obtain compound 2;

[0038] Compound 2 was synthesized into compound 3 via Stille coupling reaction;

[0039] Compound 3 was brominated with NBS to obtain polymer monomer 4;

[0040] The polymer was obtained by reacting polymer monomer 4 and compound 5 via Stille coupling reaction in an inert atmosphere.

[0041] A fifth aspect of the invention is to provide the application of the benzodithiophene-based fused-ring monomer or the polymer described herein in the photovoltaic field.

[0042] A sixth aspect of the present invention is to provide a solar cell comprising an active layer made of the polymer described herein.

[0043] Preferably, the thickness of the active layer is 100-120 nm.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] (1) The fused-ring monomer based on benzodithiophene provided by the present invention can be used as a polymerization monomer to further prepare donor polymers.

[0046] (2) The present invention is based on the preparation method of fused-ring monomers of benzodithiophene. The steps are simple. The fused-ring monomers with conjugated six-membered rings are constructed in one step by using dibromo-substituted compounds and tributyltin-substituted compounds through Stille coupling reaction.

[0047] (3) The benzodithiophene-based polymer provided by the present invention has a conjugated six-membered ring structure and can be used as a donor material in the preparation of organic photovoltaic devices. The resulting solar cell has the advantages of good stability and high photoelectric conversion efficiency, with a photoelectric conversion efficiency of up to 18.13%. Attached Figure Description

[0048] Figure 1 This is a test graph of the photoelectric physical properties of polymer PFNT-Cl in Example 1 of the present invention;

[0049] Figure 2 This is a test diagram of the photoelectric physical properties of polymer PNDT2 in Example 2 of the present invention;

[0050] Figure 3 This is the JV curve of the solar cell in Application Example 1 of this invention;

[0051] Figure 4 This is the AFM phase diagram and height diagram of the active layer in Application Example 1 of the present invention;

[0052] Figure 5 This is the JV curve of the solar cell in Application Example 2 of this invention;

[0053] Figure 6 This is the AFM phase diagram and height diagram of the active layer in Application Example 2 of the present invention;

[0054] Figure 7 This is the JV curve of the solar cell in Application Example 3 of the present invention;

[0055] Figure 8 This is the JV curve of the solar cell in Application Example 4 of this invention;

[0056] Figure 9 This is the JV curve of the solar cell in Application Example 5 of the present invention. Detailed Implementation

[0057] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0058] Unless otherwise specified, the raw materials or apparatus used in the following embodiments can be obtained from conventional commercial sources or by existing known methods.

[0059] Example 1

[0060] A fused-ring monomer based on benzodithiophene, the compound FNT-2TMS, has the following structural formula:

[0061]

[0062] The above-mentioned method for preparing fused-ring monomers based on benzodithiophene includes the following steps:

[0063] Preparation of Compound 1: 3,3'-dibromo-5,5'-di(trimethylsilyl)-2,2'-bithiophene (2 g) was dissolved in 20 mL of anhydrous tetrahydrofuran at -78 °C under nitrogen protection, followed by the slow addition of n-butyllithium (5.6 mL, 1.6 M). After reacting at -78 °C for 1 hour, trimethyltin chloride (8.95 mL, 1 M) was added, and the reaction was further carried out at room temperature for 1 hour. Then, 75 mL of water was added. After extraction with dichloromethane (3 × 50 mL), the solution was dried over anhydrous sodium sulfate. Finally, compound 1 (2.17 g, 80%) was obtained by purification by crystallization in ethanol. The NMR data of compound 1 are as follows: 1 HNMR (400MHz, CDCl3) (ppm): 7.15 (s, 2H), 0.34 (br, 18H), 0.11 (br, 18H). 13 CNMR(100MHz,CDCl3)(ppm)148.80,142.16,141.07,140.20,0.08,-8.21.

[0064] Preparation of compound FNT-2TMS: Under nitrogen protection, 1,2-dibromo-3,4,5,6-tetrafluorobenzene (1.4 g) and compound 1 (2.4 g) were added to 6 mL of dry toluene, followed by the addition of Pd2(dba)3 (70 mg) and P(o-Tol)3 (180 mg). After reflux for 12 hours, the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether as eluent to give pure product FNT-2TMS (0.52 g, 25%) as a pale gray solid. The NMR data of compound FNT-2TMS are as follows: 1 HNMR(400MHz, CDCl3)(ppm)8.16(s,2H),0.39(br,18H); 13 CNMR (100MHz, CDCl3) (ppm) 143.72 (d, J = 252Hz), 141.08, 138.58, 137.98 (d, J = 255Hz), 132.18 (t, J = 9Hz), 129.68, 113.80 (m), -0.29. 19 FNMR (376MHz, CDCl3) (ppm) -141.40 (d, J = 15.0Hz, 2F), -160.04 (d, J = 18.8Hz, 2F).

[0065] The reaction formula is as follows:

[0066]

[0067] A polymer based on benzodithiophene, namely polymer PFNT-Cl, has the following structural formula:

[0068]

[0069] The above-mentioned method for preparing polymers based on benzodithiophene includes the following steps:

[0070] Preparation of compound FNT-2Br: NBS (0.39 g) was added to a mixture of CF3COOH (32 mL), THF (16 mL), and compound FNT-2TMS (0.4 g). After reflux for 6 hours, the solvent was removed under reduced pressure. The crude product was purified by crystallization in ethanol to give a light gray solid product FNT-2Br (0.39 g, 95%). The NMR data of compound FNT-2Br are as follows: 1 HNMR (400MHz, CDCl3) (ppm): 8.16 (s, 2H). 19 FNMR (376MHz, CDCl3) (ppm) -141.24 (d, J = 18.8Hz, 2F), -157.64 (d, J = 15.0Hz, 2F).

[0071] Preparation of compound FNT-2T: Under nitrogen protection, FNT-2Br (0.25 g) and tributyl(4-octylthiophen-2-yl)stannane (0.77 g) were first added to 3 mL of dry toluene, followed by the addition of Pd2(dba)3 (15 mg) and P(o-Tolyl)3 (63 mg). After reflux for 2 hours, the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether as eluent to obtain pure product FNT-2T (0.18 g, 49%) as a yellow solid. The NMR data of compound FNT-2T are as follows: 1 HNMR (400MHz, CDCl3) (ppm): 7.72 (s, 2H), 7.00 (s, 2H), 6.86 (s, 2H), 2.59 (t, J = 7.6Hz, 4H), 1.66 (br, 4H), 1.32 (br, 20H), 0.92 (br, 6H). 13 CNMR(100MHz,CDCl3)(ppm):144.53,144.20,142.07,139.08,136.58,136.01,131.83,1 28.23,125.95,120.14,113.02,31.95,30.45,30.29,29.50,29.47,29.35,22.72,14,13. 19 FNMR (376MHz, CDCl3) (ppm) -141.74 (d, J = 15.0Hz, 2F), -159.49 (d, J = 15.0Hz, 2F).

[0072] Preparation of compound FNT-2T-2Br: Compound FNT-2T (0.51 g) was dissolved in CHCl3 (10 mL), and NBS (0.26 g) was added. After stirring at room temperature (approximately 25°C) for 3 hours, the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether as the eluent to obtain pure product FNT-2T-2Br (0.5 g, 81%) as an orange solid. The NMR data of compound FNT-2T-2Br are as follows: 1 HNMR (400MHz, CDCl3) (ppm): 7.06 (s, 2H), 6.54 (s, 2H), 2.41 (t, J = 7.6Hz, 4H), 1.54 (br, 4H), 1.37 (br, 20H), 0.95 (br, 6H). 13CNMR (100MHz, CDCl3) (ppm): 143.04, 142.97 (d, J = 249Hz), 137.70 (d, J = 258Hz), 135.59, 135.48, 131. 24,127.85,124.93,119.74(m),112.45(m),109.33,31.96,29.55,29.46,29.43,29.35,22.76,14.18. 19 FNMR (376MHz, CDCl3) (ppm) -141.59 (d, J = 18.8Hz, 2F), -158.68 (d, J = 18.8Hz, 2F).

[0073] Preparation of polymer PFNT-Cl: Under nitrogen protection, compound FNT-2T-2Br (85.88 mg) and compound M1 (119.79 mg) were first added to 4 mL of dry toluene, followed by Pd2(dba)3 (1.84 mg) and P(o-Tolyl)3 (4.86 mg). After reflux for 20 minutes, the solution became a gel. Chlorobenzene (4 mL) was added to the solution to dissolve the polymer, and the reaction was further refluxed for 3 hours. The solution was added dropwise to petroleum ether, and the precipitate was filtered. After extraction with dichloromethane and chloroform, the polymer was dissolved in chlorobenzene. The solution was added dropwise to ethanol (50 mL) with stirring. The product was collected and dried to obtain PFNT-Cl (57 mg, 36%). PFNT-Cl molecular weight (M n =42.57 kDa; PFNT-Cl polydispersity (PDI) = 1.97.

[0074] The reaction formula is as follows:

[0075]

[0076] Example 2

[0077] A fused-ring monomer based on benzodithiophene, compound 2, has the following structural formula:

[0078]

[0079] The above-mentioned method for preparing fused-ring monomers based on benzodithiophene includes the following steps:

[0080] Preparation of Compound 2: Under a nitrogen atmosphere, Pd2(dba)3 (126 mg) and P(o-Tol)3 (337 mg) were added to a reaction system containing Compound 1 (1.762 g), 5,6-dibromo-2-butylisoindoline-1,3-dione (1 g), and toluene (8 mL). After reflux for 3 hours, the system was poured into water and extracted three times with dichloromethane. The organic phases were collected and combined, dried over anhydrous sodium sulfate, and filtered. Compound 2 (0.974 g, 69%) was obtained by silica gel column chromatography using dichloromethane:petroleum ether = 1:3 as eluent. The NMR data of Compound 2 are as follows: 1 HNMR (400MHz, CDCl3) δ8.60(s,2H),7.98(s,2H),3.67(s,2H),1.49(br,6H),0.88(s,3H),0.37(s,18H). 13 CNMR(101MHz,Chloroform-d)δ141.64,138.67,135.76,129.95,129.34,127.51,120.03,37.94,30.61,20.08,13.59.

[0081] The preparation method of compound 1 is the same as that in Example 1.

[0082] The reaction formula is as follows:

[0083]

[0084] A polymer based on benzodithiophene, namely polymer PNDT2, has the following structural formula:

[0085]

[0086] The above-mentioned method for preparing polymers based on benzodithiophene includes the following steps:

[0087] Preparation of compound 3: NBS (0.862 g) was added to the reaction system of compound 2 (0.950 g) and tetrahydrofuran (10 mL), and the mixture was placed in an ice bath at 0 °C. Trifluoroacetic acid (25 mL) was added, and the mixture was gradually brought to room temperature and stirred overnight. A large amount of solid precipitated from the system. The precipitate was filtered and washed with dichloromethane to obtain compound 3 (0.936 g, 96%).

[0088] Preparation of Compound 4: Compound 3 (0.850 g), Pd2(dba)3 (74 mg), and P(o-tolyl)3 (198 mg) were added to a reactor flask. Under nitrogen protection, tributyl(4-hexylthiophene-2-yl)stanane (2.228 g) and toluene (10 mL) were then added to the reaction system. After reflux for 3 hours, the system was poured into water and extracted three times with dichloromethane. The organic phases were collected and combined, dried over anhydrous sodium sulfate, and filtered. Compound 4 (0.895 g, 79%) was obtained by silica gel column chromatography using dichloromethane:petroleum ether = 1:2 (v / v) as eluent. The NMR data of Compound 4 are as follows: 1 HNMR(400MHz,Chloroform-d)δ8.63(s,2H),7.90(s,2H),7.18(s,2H),6.95(s,2H),3. 71(t,J=7.6Hz,2H),2.64(t,J=7.6Hz,4H),1.69(br,6H),1.37(br,14H),0.96(br,9H). 13 CNMR(101MHz,Chloroform-d)δ167.69,144.20,136.89,135.84,134.66,131.78,128.58,127.16,126 .20,120.34,119.35,117.02,37.64,31.74,30.56,30.46,30.26,29.17,22.68,20.23,14.15,13.67.

[0089] Preparation of compound S1: NBS (0.363 g) was added to the reaction system of compound 4 (0.712 g) and CHCl3 (15 mL). After stirring overnight, the solvent was evaporated under vacuum, and compound S1 (0.733 g, 84%) was obtained by silica gel column chromatography using dichloromethane:petroleum ether = 1:3 as the eluent. The NMR data of compound S1 are as follows: 1 HNMR(400MHz,Chloroform-d)δ8.48(s,2H),7.70(s,2H),7.00(s,2H),3.68(t,J =7.6Hz,2H),2.60(t,J=7.6Hz,4H),1.66(br,6H),1.39(br,14H),0.97(br,9H). 13CNMR(101MHz,Chloroform-d)δ167.50,143.30,136.04,135.42,134.68,131.58,128.49,127.39,125 .53,119.21,117.07,109.66,37.78,31.66,30.50,29.64,29.58,29.14,22.67,20.24,14.16,13.65.

[0090] Preparation of polymer PNDT2: Under a nitrogen atmosphere, compound S1 (85.58 mg), compound M2 (116.49 mg), P(o-tolyl)3 (4.86 mg), Pd2(dba)3 (1.83 mg), and dry toluene (4.6 mL) were added to a 48 mL reaction flask and refluxed at 120 °C. After reflux for 30 minutes, the solution became difficult to stir. Chlorobenzene (4.6 mL) was added to the solution to dissolve the polymer. The reaction was continued with stirring for one and a half hours. The solution was added to ethanol, and the precipitate was filtered. After Soxhlet extraction with chloroform, followed by extraction with chlorobenzene, the concentrated solution was poured into 100 mL of ethanol, stirred, and filtered. The polymer was filtered and dried under reduced pressure to obtain PNDT2 product (0.08 g, 51%). Molecular weight of PNDT2 (Mn) = 39.14 kDa; polydispersity (PDI) of PNDT2 = 2.00.

[0091] The reaction formula is as follows:

[0092]

[0093] Example 3

[0094] A fused-ring monomer based on benzodithiophene, compound 5, has the following structural formula:

[0095]

[0096] The above-mentioned method for preparing fused-ring monomers based on benzodithiophene includes the following steps:

[0097] 5,6-Dibromo-2-(2-ethylhexyl)-4,7-difluoro-2H-benzotriazole (0.8 g), compound 1 (1.197 g), Pd2(dba)3 (86 mg), and P(o-Tol)3 (229 mg) were added to a reactor flask to displace the inert environment. Then, toluene (4 mL) was added to the reaction system. After reflux for 3 hours, the system was poured into water and extracted three times with dichloromethane. The organic phases were collected and combined, dried over anhydrous sodium sulfate, and filtered. Using dichloromethane:petroleum ether at a ratio of 1:2 as eluent, silica gel column chromatography was used to obtain product compound 5 (0.282 g, 26%). The NMR data for compound 5 are as follows: 1 HNMR (400MHz, CDCl3) δ8.41 (s, 2H), 4.83 (d, J = 7.2Hz, 2H), 4.66 (m, J = 7.2Hz, 1H), 0.47 (m, 18H), 0.37 (s, 6H), 0.20 (s, 4H).

[0098] The preparation method of compound 1 is the same as that in Example 1.

[0099] The reaction formula is as follows:

[0100]

[0101] A polymer based on benzodithiophene, polymer P1, has the following structural formula:

[0102]

[0103] The above-mentioned method for preparing polymers based on benzodithiophene includes the following steps:

[0104] Preparation of compound S2: Compound 5 (0.230 g) and NBS (0.185 g) were added to a round-bottom flask. Tetrahydrofuran (6 mL) was then added to the reaction system. The mixture was placed in an ice bath at 0 °C and stirred for 10 minutes. Trifluoroacetic acid (25 mL) was then added, and the mixture was gradually allowed to return to room temperature while stirring overnight. A large amount of solid precipitated. The precipitate was filtered and washed with dichloromethane to obtain the product compound S2 (0.106 g, 45%). The NMR data for compound S2 are as follows: 1 HNMR (400MHz, CDCl3) δ8.19 (s, 2H), 4.84 (d, J = 7.2Hz, 2H), 2.39 (m, 1H), 1.35 (m, 8H), 0.98 (m, 3H), 0.89 (m, 3H).

[0105] Preparation of polymer P1: Under nitrogen protection, compound S2 (29.36 mg), compound M3 (54.28 mg), P(o-tolyl)3 (2.43 mg), Pd2(dba)3 (0.92 mg), and dry toluene (2 mL) were added to a 15 mL reaction flask and refluxed at 120 °C. After reflux for 30 minutes, the solution became difficult to stir. Chlorobenzene (2 mL) was added to the solution to dissolve the polymer. The reaction was continued with stirring for two hours. The solution was added to ethanol, and the precipitate was filtered. After Soxhlet extraction with chloroform, the concentrated solution was poured into 100 mL of ethanol, stirred, and filtered. The polymer was filtered and dried under reduced pressure to obtain polymer P1 (0.025 g, 41%).

[0106] The reaction formula is as follows:

[0107]

[0108]

[0109] Example 4

[0110] A fused-ring monomer based on benzodithiophene, compound 6, has the following structural formula:

[0111]

[0112] The above-mentioned method for preparing fused-ring monomers based on benzodithiophene includes the following steps:

[0113] Under nitrogen protection, 1 g of 4,5-dibromo-2-cyanothiophene and 2.4 g of compound 1 were added to 2.5 mL of dry toluene, followed by the addition of Pd2(dba)3 (100 mg) and P(o-Tol)3 (270 mg). After reflux for 12 hours, the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether to dichloromethane in a 3:1 ratio as eluent to give compound 6 (0.53 g, 34%) as a white powder. The NMR data for compound 6 are as follows: 1 HNMR(400MHz, CDCl3)(ppm)8.32(s,1H),7.83(s,1H),7.68(s,1H),0.45(br,18H).

[0114] The preparation method of compound 1 is the same as that in Example 1.

[0115] The reaction formula is as follows:

[0116]

[0117] A polymer based on benzodithiophene, polymer P2, has the following structural formula:

[0118]

[0119] The above-mentioned method for preparing polymers based on benzodithiophene includes the following steps:

[0120] Preparation of Compound 7: NBS (2.25 g) was added to a mixture of THF (20 mL) and Compound 6 (0.35 g). After reflux for 6 hours, the solvent was removed under reduced pressure. The crude product was purified by crystallization in ethanol to give a white solid, Compound 7 (0.34 g, 95%). The NMR data for Compound 7 are as follows: 1 HNMR(400MHz, CDCl3)(ppm):8.20(s,1H),7.74(s,1H),7.61(s,1H).

[0121] Preparation of Compound 8: Under nitrogen protection, Compound 7 (0.27 g) and tributyl(4-hexylthiophen-2-yl)stannane (0.92 g) were first added to 3 mL of dry toluene, followed by the addition of Pd2(dba)3 (17 mg) and P(o-tolyl)3 (46 mg). After reflux for 2 hours, the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether to dichloromethane at a ratio of 1:1 as the eluent, yielding the pure product Compound 8 (0.16 g, 42%) as a yellow powder. The NMR data of Compound 8 are as follows: 1 HNMR(400MHz, CDCl3)(ppm):8.24(s,1H),7.70(s,1H),7.54(s,1H),7.21(s,2H ),6.96(s,2H),2.65(t,J=8Hz,4H),1.68(br,4H),1.36(br,12H),0.92(br,6H).

[0122] Preparation of compound S3: Compound 8 (0.11 g) was dissolved in CHCl3 (6 mL), and NBS (0.07 g) was added. After stirring at room temperature for 3 hours, the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether as eluent to obtain pure product S3 (0.13 g, 96%) as a yellow powder. The NMR data of compound S3 are as follows: 1 HNMR (400MHz, CDCl3) (ppm): 8.14 (s, 1H), 7.52 (s, 1H), 7.37 (s, 1H), 7.02 (s, 2H), 2.59 (t, J = 8Hz, 4H), 1.64 (br, 4H), 1.37 (br, 12H), 0.93 (br, 6H).

[0123] Preparation of polymer P2: Under nitrogen protection, compound S3 (38.09 mg) and compound M1 (59.89 mg) were first added to 2 mL of dry toluene, followed by Pd2(dba)3 (0.92 mg) and P(o-tolyl)3 (2.43 mg). After reflux for 20 minutes, the solution became a gel. Chlorobenzene (2 mL) was added to the solution to dissolve the polymer, and the mixture was further refluxed for 10 minutes. The solution was added dropwise to petroleum ether, and the precipitate was filtered off. After extraction with dichloromethane and chloroform, the polymer was dissolved in chlorobenzene. The solution was added dropwise to ethanol (20 mL) with vigorous stirring. The solution was collected and dried to obtain polymer P2 (29 mg, 39%).

[0124] The reaction formula is as follows:

[0125]

[0126] Example 5

[0127] A fused-ring monomer based on benzodithiophene, compound 9, has the following structural formula:

[0128]

[0129] The above-mentioned method for preparing fused-ring monomers based on benzodithiophene includes the following steps:

[0130] Under nitrogen protection, 2,5-dicyano-3,4-dibromothiophene (1.74 g) and compound 1 (3.79 g) were first added to 5 mL of dry toluene, followed by the addition of Pd2(dba)3 (16 mg) and P(o-Tol)3 (44 mg). After reflux for 12 hours, the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether to dichloromethane in a 3:1 ratio as the eluent to give the pure product compound 9 (1.61 g, 61%) as a bright yellow solid. The NMR data of compound 9 are as follows: 1 HNMR(400MHz, CDCl3)(ppm)8.45(s,2H),0.46(br,18H).

[0131] The preparation method of compound 1 is the same as that in Example 1.

[0132] The reaction formula is as follows:

[0133]

[0134] A polymer based on benzodithiophene, polymer P3, has the following structural formula:

[0135]

[0136] The above-mentioned method for preparing polymers based on benzodithiophene includes the following steps:

[0137] Preparation of Compound 10: NBS (13 g) was added to a mixture of THF (55 mL) and Compound 9 (1.6 g). After reflux for 10 hours, the solvent was removed under reduced pressure. The crude product was purified by crystallization in ethanol to give a yellow solid, Compound 10 (1.5 g, 95%). The NMR data of Compound 10 are as follows: 1 HNMR (400MHz, CDCl3) (ppm): 8.36 (s, 2H).

[0138] Preparation of Compound 11: Under nitrogen protection, Compound 10 (0.7 g) and tributyl(4-hexylthiophen-2-yl)stannane (2.8 g) were first added to 30 mL of dry toluene, followed by the addition of Pd2(dba)3 (42 mg) and P(o-tolyl)3 (112 mg). After reflux for 20 minutes, the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether to dichloromethane at a ratio of 2:1 as the eluent, yielding the pure product Compound 11 (0.57 g, 59%) as a purple solid. The NMR data for Compound 11 are as follows: 1 HNMR (400MHz, CDCl3) (ppm): 8.18 (s, 2H), 7.18 (s, 2H), 6.96 (s, 2H), 2.63 (t, J = 8Hz, 4H), 1.68 (br, 4H), 1.36 (br, 12H), 0.92 (br, 6H).

[0139] Preparation of compound S4: Compound 11 (0.5 g) was dissolved in CHCl3 (17 mL), and NBS (0.42 g) was added. After stirring at 50 °C for 10 hours, the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using chloroform as the eluent to obtain the pure product compound S4 (0.58 g, 93%) as a purple solid. The NMR data of compound S4 are as follows: 1 HNMR (400MHz, CDCl3) (ppm): 8.27 (s, 2H), 7.09 (s, 2H), 2.60 (t, J = 8Hz, 4H), 1.64 (br, 4H), 1.36 (br, 12H), 0.92 (br, 6H).

[0140] Preparation of polymer P3: Under nitrogen protection, compound S4 (39.34 mg) and compound M1 (59.89 mg) were first added to 2 mL of dry toluene, followed by Pd2(dba)3 (0.92 mg) and P(o-tolyl)3 (2.43 mg). After reflux for 40 minutes, the solution became a gel. Chlorobenzene (2 mL) was added to the solution to dissolve the polymer, and the mixture was further refluxed for 50 minutes. The solution was added dropwise to petroleum ether, and the precipitate was filtered off. After extraction with dichloromethane and chloroform, the polymer was dissolved in chlorobenzene. The solution was added dropwise to ethanol (20 mL) with vigorous stirring. The solution was collected and dried to obtain polymer P3 (33 mg, 44%).

[0141] The reaction formula is as follows:

[0142]

[0143] Photoelectric physical property testing of polymer donor materials

[0144] The electrochemical energy levels of the polymer donor material PFNT-Cl in Example 1 and the polymer donor material PNDT2 in Example 2 were measured by cyclic voltammetry, with ferrocene (Fc) as an internal standard (-4.8 eV), and E was calculated from the initial potentials of oxidation and reduction. HOMO and E LUMO energy level.

[0145] The photoelectric physical properties of the polymer donor material PFNT-Cl in Example 1 were tested as follows: Figure 1 As shown, Figure 1 (a) shows the energy level diagrams of PFNT-Cl and N3 (calculated based on the electrochemical data of PFNT-Cl obtained by cyclic voltammetry); (b) shows the electrochemical data of PFNT-Cl obtained by cyclic voltammetry; (c) shows the visible and ultraviolet absorption spectra of the PFNT-Cl and N3 films (the films were fabricated using the same conditions as the donor material in the high-performance device, i.e., concentration, rotation speed, annealing temperature, and time. Specifically, PFNT-Cl was dissolved in 4.2 mg / mL CF (chloroform) at 110 °C, cooled, spin-coated onto a quartz plate at 2000 rpm, and annealed at 110 °C for 5 minutes. The film samples were tested using a spectrophotometer (SHIMADZUUV-1780). Figure 1 (a) E of PFNT-Cl can be obtained HOMO and E LUMO The energy levels are -5.47 eV and -3.51 eV, respectively; from Figure 1(c) The maximum absorption peak of the PFNT-Cl film is 550 nm, and the absorption range is 450 nm-620 nm, which is very well matched with the absorption range of N3 (600 nm-900 nm), which is conducive to achieving maximum absorption of sunlight. Figure 1 In (a), EnergyLevel refers to the energy level. Figure 1 In (b), Current refers to electric current and Voltage refers to voltage. Figure 1 In (c), AbsorptionIntensity refers to the absorption intensity.

[0146] The structural formula of N3 is as follows:

[0147]

[0148] The photoelectric physical properties of the polymer donor material PNDT2 in Example 2 were tested as follows: Figure 2 As shown, Figure 2 (a) shows the energy level diagrams of PNDT2 and eC9; (b) shows the electrochemical data of PNDT2 measured using cyclic voltammetry; and (c) shows the visible-ultraviolet absorption spectra of the PNDT2 and eC9 films. Figure 2 (a) The E of PNDT2 can be obtained HOMO and E LUMO The energy levels are -5.41 eV and -3.58 eV, respectively; from Figure 2 (c) The maximum absorption peak of the PNDT2 film is 551 nm, and the absorption range is 450 nm-620 nm, which is very well matched with the absorption range of eC9 (600 nm-900 nm), which is conducive to achieving maximum absorption of sunlight.

[0149] The structural formula of eC9 is as follows:

[0150]

[0151] Application Example 1

[0152] The structure of a solar cell based on PFNT-Cl:N3 is: ITO / PEDOT:PSS / PFNT-Cl:N3 / PNDIT-F3N / Ag; where the structural formula of PNDIT-F3N is as follows:

[0153]

[0154] The fabrication method of PFNT-Cl:N3-based solar cells is as follows: An aqueous solution of PEDOT:PSS is spin-coated onto ITO glass at 6000 rpm. After annealing in air at 150°C for 15 minutes, the glass is transferred to a glove box. A chloroform solution of 9.24 mg / mL PFNT-Cl:N3 (1:1.2) is spin-coated onto the PEDOT:PSS layer and annealed at 110°C for 5 minutes, resulting in an active layer thickness of approximately 105 nm. A methanol solution of PNDIT-F3N (0.5 mg / mL) is spin-coated onto the active layer. A 150 nm thick Ag electrode is then deposited on the top layer using a mask, yielding a test area of ​​0.04 cm². 2 Solar cells.

[0155] 100mW·cm calibrated using a standard solar cell -2 The solar radiation intensity test yielded the current-voltage characteristic curve (JV curve) as follows: Figure 3 As shown, the PFNT-Cl:N3-based solar cell achieved a maximum photoelectric conversion efficiency of 18.10% and a short-circuit current of 26.56 mA·cm⁻¹. -2 The open-circuit voltage is 0.853V and the fill factor is 0.799. Figure 3 In this context, CurrentDensity refers to current density, and Voltage refers to voltage.

[0156] The active layer was examined using atomic force microscopy (AFM), such as... Figure 4 As shown. From Figure 4 (a), i.e., the AFM phase diagram, shows that PFNT-Cl:N3 has a good nanofiber structure, indicating that the polymers PFNT-Cl and N3 have a good nanofiber structure and good morphological compatibility. The nanofiber structure is beneficial for phase separation, charge extraction and transport, and is an ideal structure for organic solar cells (OSCs). From Figure 4 (b) As can be seen from the AFM height diagram, the root mean square roughness (Rq) of PFNT-Cl:N3 is 0.84 nm.

[0157] Photovoltaic devices based on PFNT-Cl:N3 retained 90.1% of their original efficiency after continuous annealing at 60℃ for 200 hours, while devices based on PM6:N3 retained only 85.6% of their original efficiency. This indicates that photovoltaic devices based on PFNT-Cl polymer have superior device stability.

[0158] The structural formula for PM6 is as follows:

[0159]

[0160] Application Example 2

[0161] The structure of a solar cell based on PNDT2:eC9 is: ITO / PEDOT:PSS / PNDT2:eC9 / PNDIT-F3N / Ag.

[0162] The fabrication method of the PNDT2:eC9-based solar cell is as follows: An aqueous solution of PEDOT:PSS is spin-coated onto ITO glass at 6000 rpm. After annealing in air at 150°C for 15 minutes, the glass is transferred to a glove box. A chloroform solution of 11.25 mg / mL PNDT2:eC9 (1:1.5) is spin-coated onto the PEDOT:PSS layer and annealed at 110°C for 5 minutes to obtain an active layer with a thickness of approximately 120 nm. A PNDIT-F3N methanol solution (0.5 mg / mL) is spin-coated onto the active layer. A 150 nm thick Ag electrode is deposited on the top layer using a mask, resulting in a test area of ​​0.0486 cm². 2 Solar cells.

[0163] 100mW·cm calibrated using a standard solar cell -2 The solar radiation intensity test yielded the JV curve as follows: Figure 5 As shown, the PNDT2:eC9-based solar cell achieved a maximum photoelectric conversion efficiency of 18.13% and a short-circuit current of 26.33 mA·cm⁻¹. -2 The open-circuit voltage is 0.861V and the fill factor is 0.800.

[0164] The active layer was tested using AFM, such as Figure 6 As shown. From Figure 6 (a), i.e., the AFM phase diagram, shows that PNDT2:eC9 has a good nanofiber structure, indicating that the polymers PNDT2 and eC9 have a good nanofiber structure and good morphological compatibility. The nanofiber structure is beneficial for phase separation, charge extraction and transport, and is an ideal structure for organic solar cells (OSCs). From Figure 6 (b) As can be seen from the AFM height diagram, the root mean square roughness (Rq) of the PNDT2:eC9 surface is 0.98 nm.

[0165] Photovoltaic devices based on PNDT2:eC9 retained 93.1% of their original efficiency after continuous annealing at 60℃ for 200 hours, while devices based on PM6:eC9 retained only 86.7% of their original efficiency, indicating that photovoltaic devices based on PNDT2 polymer have better device stability.

[0166] Application Example 3

[0167] The structure of the solar cell based on P1:eC9 is: ITO / PEDOT:PSS / P1:eC9 / PNDIT-F3N / Ag.

[0168] The fabrication method of the P1:eC9-based solar cell is as follows: An aqueous solution of PEDOT:PSS is spin-coated onto ITO glass at 6000 rpm. After annealing in air at 150°C for 15 minutes, the glass is transferred to a glove box. A chloroform solution of 16.25 mg / mL P1:eC9 (1:1.5) is spin-coated onto the PEDOT:PSS layer and annealed at 110°C for 5 minutes, resulting in an active layer thickness of approximately 100 nm. A PNDIT-F3N methanol solution (0.5 mg / mL) is spin-coated onto the active layer. A 150 nm thick Ag electrode is then deposited on the top layer using a mask, yielding a test area of ​​0.0486 cm². 2 Solar cells.

[0169] 100mW·cm calibrated using a standard solar cell -2 The solar radiation intensity test yielded the JV curve as follows: Figure 7 As shown, the P1:eC9-based solar cell achieved a maximum photoelectric conversion efficiency of 11.56% and a short-circuit current of 24.54 mA·cm⁻¹. -2 The open-circuit voltage is 0.843V and the fill factor is 0.559.

[0170] Application Example 4

[0171] The structure of a P2:N3-based solar cell is: ITO / PEDOT:PSS / P2:N3 / PNDIT-F3N / Ag.

[0172] The fabrication method of P2:N3-based solar cells is as follows: An aqueous solution of PEDOT:PSS is spin-coated onto ITO glass at 6000 rpm. After annealing in air at 150°C for 15 minutes, the glass is transferred to a glove box. A chloroform solution of 11.18 mg / mL P2:N3 (1:1.6) (with 0.5% v / v CN added) is spin-coated onto the PEDOT:PSS layer and annealed at 110°C for 5 minutes, resulting in an active layer thickness of approximately 100 nm. A PNDIT-F3N methanol solution (0.5 mg / mL) is spin-coated onto the active layer. A 150 nm thick Ag electrode is deposited on the top layer using a mask, yielding a test area of ​​0.0486 cm². 2 Solar cells.

[0173] 100mW·cm calibrated using a standard solar cell -2 The solar radiation intensity test yielded the JV curve as follows: Figure 8 As shown, the P2:N3-based solar cell achieved a maximum photoelectric conversion efficiency of 15.72% and a short-circuit current of 24.33 mA·cm⁻¹. -2 The open-circuit voltage is 0.872V and the fill factor is 0.741.

[0174] Application Example 5

[0175] The structure of a P3:N3-based solar cell is: ITO / PEDOT:PSS / P3:N3 / PNDIT-F3N / Ag.

[0176] The fabrication method of P3:N3-based solar cells is as follows: An aqueous solution of PEDOT:PSS is spin-coated onto ITO glass at 6000 rpm. After annealing in air at 150°C for 15 minutes, the glass is transferred to a glove box. A chloroform solution of 11.18 mg / mL P3:N3 (1:1.6) (with 0.5% v / v CN added) is spin-coated onto the PEDOT:PSS layer and annealed at 110°C for 5 minutes, resulting in an active layer thickness of approximately 100 nm. A PNDIT-F3N methanol solution (0.5 mg / mL) is spin-coated onto the active layer. A 150 nm thick Ag electrode is deposited on the top layer using a mask, yielding a test area of ​​0.0486 cm². 2 Solar cells.

[0177] 100mW·cm calibrated using a standard solar cell -2 The solar radiation intensity test yielded the JV curve as follows: Figure 9 As shown, the P3:N3-based solar cell achieved a maximum photoelectric conversion efficiency of 17.64% and a short-circuit current of 26.21 mA·cm⁻¹. -2 The open-circuit voltage is 0.858V and the fill factor is 0.784.

[0178] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A polymer donor material, characterized in that, The raw materials for preparing the polymer donor material include benzodithiophene-based fused-ring monomers, which have the following general structural formula: ； Wherein, C is one of the following structures: ； R is H or any alkyl chain of C1-C24; Y is one of O and S; X1, X2, X3, X4, X5, X6, X7, X8, X9, X 10 X 11 X 12 It is independently selected from one of H, F, Cl, and CN.

2. The polymer donor material according to claim 1, characterized in that, The benzodithiophene-based fused-ring monomer has one of the following structures:

3. The polymer donor material according to claim 1, characterized in that, The method for preparing the fused-ring monomer based on benzodithiophene includes the following steps: The benzodithiophene-based fused-ring monomer was obtained by Stille coupling reaction using dibromo-substituted compounds and tributyltin-substituted compounds.

4. The polymer donor material according to claim 1, characterized in that, The polymer donor material has the following general structural formula: ； L1 has one of the following structures: ； D has the following structure: ； X 13 Selected from F and Cl; Y is selected from O and S; R1, R2, R 11 R 12 Independently selected from any alkyl chain of H or C1-C24; n is a positive integer.

5. The polymer donor material according to claim 4, characterized in that, The polymer donor material has one of the following structures:

6. The method for preparing the polymer donor material according to any one of claims 1-5, characterized in that, Includes the following steps: In an inert atmosphere, the benzodithiophene-based fused-ring monomer is coupled via Stille coupling to obtain the polymer donor material.

7. The application of the polymer donor material according to any one of claims 1-5 in the photovoltaic field.

8. A solar cell, characterized in that, The solar cell includes an active layer, which is made of the polymer donor material according to any one of claims 1-5.

9. The solar cell according to claim 8, characterized in that, The thickness of the active layer is 100-120 nm.

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