A class of polymer materials based on dithiazolylbenzothiophene structural units and their applications

Abstract

The present invention belongs to the field of organic optoelectronics, specifically relating to a polymer material containing dithiazolylbenzothiophene structural units and their application in organic solar cells. The polymer material has a molecular structure as shown in Formula (I), with substituents as described in the specification. The present invention utilizes dithiazolylbenzothiophene units as electron-withdrawing units, introducing them into the polymer to construct a wide-bandgap donor material. This polymer material exhibits excellent crystallinity and donor-acceptor compatibility, resulting in high carrier mobility and photovoltaic performance. When used in organic solar cells, it can achieve a power conversion efficiency (PCE) exceeding 19%, demonstrating promising application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of organic photoelectric technology, and in particular relates to a polymer material containing dithiazolylbenzothiophene structural units and the application thereof in organic solar cells. Background Art

[0002] As the third generation of solar energy technology, organic solar cells (OSCs) have important application prospects in flexible wearable portable devices and indoor photovoltaics due to their advantages such as flexibility, light weight and tunable absorption spectrum. In recent years, with the development of non-fullerene acceptor materials (NFAs), the energy conversion efficiency of binary devices has rapidly increased to over 18%, and the efficiency of ternary devices has exceeded 20%. Compared with the rapid development of NFAs, the development of donor polymers has been relatively slow. So far, only a few donor polymers (such as PM6, D18, PBQx, etc.) have achieved high efficiencies of over 19% in binary devices. Therefore, the development of high-performance donor polymers suitable for non-fullerene systems is an important direction to further improve the efficiency of OSCs.

[0003] In recent years, among numerous donor materials, donor-acceptor (DA) conjugated polymers containing benzodithiazole (BDTz) structures have demonstrated excellent optoelectronic properties, with record-breaking efficiency, due to their efficient intramolecular charge transfer and high crystallinity due to their high number of condensed rings. For example, the BDTz-based donor polymer PBB1-F can effectively optimize photon capture, achieving an efficiency of 16.84% in thick-film flexible OSCs (Energy Environ. Sci., 2021, 14, 5968). Furthermore, the BDTz-based donor polymer PBB-Cl exhibits superior donor-acceptor compatibility with BTP-eC9 compared to PM6, achieving an efficiency of 19.04% for PM6:PBB-Cl:BTP-eC9 (Adv. Mater., 2024, 36, 2312959). In addition, Itaru Osaka's group reported a polymer containing 2,3-thiophene-fused rings called BDTz, achieving a binary efficiency of 15.9% (Adv. Sci. 2023, 10, 2205682). By adding an ester group to the acceptor unit, the binary photoelectric efficiency was increased to 17.4% (Angew. Chem. Int. Ed. 2024, e202409814). Overall, BDTz-based donor polymers, with their high crystallinity and low energy levels, can achieve high photovoltaic performance in non-fullerene systems, making them a hot topic in research on donor materials for organic solar cells.

[0004] Although the BDTz unit gives the polymer the advantages of high crystallinity and low energy level, it also leads to poor solubility and excessive phase separation in the donor-acceptor mixed film, which seriously affects the active layer morphology and photovoltaic device performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a polymer material containing dithiazolylbenzothiophene structural units and the application of the polymer material in organic solar cells.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A class of polymer materials based on dithiazolylbenzothiophene structural units, wherein the polymer material has a molecular structure as shown in formula (I):

[0008]

[0009] Where,

[0010] R1, R2, and R3 may be the same or different and may be selected from hydrogen, halogen, cyano, nitro, carbonyl, carboxyl, ester, hydroxyl, C1-C 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Silane groups, C1-C 20 Alkylthio, C2-C 20 Alkenyl, C2-C 20 Alkynyl; unsubstituted or replaced by at least one C1-C 20 an alkyl-substituted amino, aryl or heteroaryl group;

[0011] A is selected from any one of the following structures:

[0012]

[0013] D is selected from any one of the following structures:

[0014]

[0015] X is H, F or Cl;

[0016] a and b may be the same or different and are natural numbers from 0 to 2, and n represents the degree of polymerization and is a natural number between 2 and 1000.

[0017] Preferably, the polymer material is of the formula:

[0018] R1, R2, and R3 may be the same or different and may be selected from hydrogen, halogen, cyano, nitro, carbonyl, carboxyl, ester, hydroxyl, C1-C 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Silane groups, C1-C 20 Alkylthio, C2-C 20 Alkenyl, C2-C 20Alkynyl; unsubstituted or replaced by at least one C1-C 20 an alkyl-substituted amino group, a phenyl group, or a thienyl group;

[0019] A is selected from any one of the following structures:

[0020]

[0021] D is selected from any one of the following structures:

[0022]

[0023] X is H, F or Cl;

[0024] a and b may be the same or different and are natural numbers from 0 to 2, and n represents the degree of polymerization and is a natural number between 2 and 1000.

[0025] More preferably, the polymer material is of the formula:

[0026] R1, R2, and R3 may be the same or different and may be selected from hydrogen, halogen, cyano, nitro, carbonyl, carboxyl, ester, hydroxyl, C1-C 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Silane groups, C1-C 20 Alkylthio, C2-C 20 Alkenyl, C2-C 20 unsubstituted or substituted by at least one C1-C8 alkyl group, phenyl or thienyl;

[0027] A is selected from any one of the following structures:

[0028]

[0029] D is selected from any one of the following structures:

[0030]

[0031] X is H, F or Cl;

[0032] a and b may be the same or different and are natural numbers from 0 to 2, and n represents the degree of polymerization and is a natural number between 2 and 1000.

[0033] A method for preparing a polymer material based on a dithiazolylbenzothiophene structural unit comprises mixing a monomer containing a dithiazolylbenzothiophene structure with a monomer containing a unit D, carrying out a polymerization reaction under a catalyst, and obtaining a polymer donor material having a dithiazolylbenzothiophene structure shown in formula (I) through purification and separation.

[0034] The catalyst is a palladium catalyst; the molar ratio of the monomer based on the dithiazolylbenzothiophene structure to the monomer D is equal to 1.

[0035] The polymerization reaction temperature is 80-150° C., and the solvent used is toluene and / or N,N-dimethylformamide. When toluene and N,N-dimethylformamide are mixed, the volume ratio is 0-1.

[0036] An application of the polymer material based on dithiazobenzothiophene structural units, and an application of the polymer as an electron donor material in an organic photoelectric device.

[0037] The organic photoelectric device is an organic solar cell, an organic electroluminescent device, an organic field effect transistor, an organic detector and a photoelectric device.

[0038] The polymer material can be used as an electron donor of an organic photoelectric material and applied in an organic solar cell, with an energy conversion efficiency reaching 19%.

[0039] An organic solar cell device comprises a substrate, an anode, an anode modification layer, a photoactive layer, a cathode modification layer and a cathode. The photoactive layer is a thin film formed by mixing the polymer donor and the acceptor.

[0040] The polymer donor material and the electron acceptor material are dissolved in a solvent and coated on a conductive substrate to form a thin film, on which a metal electrode is formed to obtain a corresponding photoelectric device. The mass ratio of the donor material to the electron acceptor material used is 1:0.1 to 1:10.

[0041] The solvent is at least one of o-dichlorobenzene, chlorobenzene, chloroform, tetrahydrofuran, toluene and o-xylene.

[0042] The electron acceptor material is one of organic electron acceptors such as fullerene derivatives, ITIC and its derivatives, Y6 and its derivatives, PYT and its derivatives, N2200 and its derivatives.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention provides a novel polymer donor material, which has good solubility and photoelectric properties, can be used to prepare solar cells with high energy conversion efficiency, and is an excellent donor material.

[0045] (1) The preparation method provided by the present invention introduces the dithiazolylbenzothiophene structure as an electron-withdrawing unit into the polymer donor, which can synergistically obtain good crystallinity and donor-acceptor compatibility, which is conducive to obtaining relatively excellent photoelectric properties.

[0046] (2) The dithiazolylbenzothiophene-based polymer material provided by the present invention has an appropriate absorption spectrum and energy level, can be matched with a variety of receptor materials, and is applied to a variety of devices such as organic solar cells, organic photodetectors, organic light-emitting diodes, perovskite solar cells, and organic field-effect transistors. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0048] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of compound 1 synthesized in Example 1 of the present invention.

[0049] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of compound 2 synthesized in Example 1 of the present invention.

[0050] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of compound 3 synthesized in Example 1 of the present invention.

[0051] Figure 4 This is the hydrogen nuclear magnetic resonance spectrum of compound 4 synthesized in Example 1 of the present invention.

[0052] Figure 5 This is the hydrogen nuclear magnetic resonance spectrum of compound 5 synthesized in Example 1 of the present invention.

[0053] Figure 6 This is the hydrogen nuclear magnetic resonance spectrum of the polymer donor P1 synthesized in Example 1 of the present invention.

[0054] Figure 7 This is the absorption spectrum of the polymer donor P1 synthesized in Example 1 of the present invention in solution and film.

[0055] Figure 8 This is the absorption spectrum of the polymer donor P2 synthesized in Example 2 of the present invention in solution and film.

[0056] Figure 9 This is a molecular structure diagram of the device and active layer used in Example 4 of the present invention.

[0057] Figure 10 The current-voltage (JV) curve of the organic solar cell based on the polymer donor P1 of the present invention.

[0058] Figure 11 : is the external quantum efficiency (EQE) curve of the organic solar cell based on the polymer donor P1 of the present invention. DETAILED DESCRIPTION

[0059] To better illustrate the present invention, the technical solutions of the present invention are further illustrated below through specific embodiments, which do not limit the scope of protection of the present invention:

[0060] The polymer materials of the present invention incorporate a dithiazolylbenzothiophene structure into the conjugated polymer backbone to prepare a series of novel polymer donor materials. These materials exhibit an expanded conjugated plane and dipole modulation, enhancing interactions with acceptor molecules. This not only increases the material's carrier mobility but also improves its compatibility with the acceptor, reducing static disorder in the charge transfer state at the D / A interface and device non-radiative energy loss. These donor materials possess appropriate electronic energy levels and high carrier transport properties, and the hybrid films exhibit suitable phase-separated morphologies, achieving high energy conversion efficiency in organic solar cells.

[0061] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0062] The experimental materials and reagents used in the following experimental examples can be obtained through commercial channels or known experimental methods.

[0063] Example 1: Synthesis of polymer P1

[0064]

[0065] (1) 4,4'-dibromo-2,2'-bis(triisopropylsilyl)-5,5'-bithiazole (1.5 g), (2,5-dichlorothiophen-3-yl)trimethyltin (1.19 g), Pd(PPh3)4 (270 mg), and anhydrous DMF (30 mL) were added to a 100 mL Schlenck tube in sequence. The mixture was reacted at 110°C for 12 hours under nitrogen protection. After cooling to room temperature, 30 mL of saturated sodium chloride aqueous solution was added and the mixture was extracted three times with petroleum ether. The organic layer was evaporated under reduced pressure and passed through a silica gel column with dichloromethane:petroleum ether (1:7) as the eluent to obtain the yellow oily product 1 (375 mg, yield 23%). NMR data of product 1: 1 H NMR (600MHz, CDCl3): δ6.81 (s, 1H), 1.48 (m, J = 7.5Hz, 3H), 1.41 (sept, J = 7.5Hz, 3H), 1.20-1.15 (m, 18H), 1.15-1.10 (m, 18H).

[0066] (2) 1 (370 mg), palladium acetate (11.7 mg), tricyclohexylphosphine tetrafluoroborate (38.3 mg), cesium carbonate (339 mg), and anhydrous 1,4-dioxane (10 mL) were added to a 25 mL Schlenck tube in sequence. The reaction was carried out at 140°C under nitrogen protection overnight. After cooling to room temperature, 5 mL of saturated sodium chloride aqueous solution was added and the mixture was extracted three times with dichloromethane. The organic layer was evaporated under reduced pressure and passed through a silica gel column with dichloromethane: petroleum ether (1:4) as the eluent to obtain a yellow oily product 2 (137.7 mg, yield 42%). The NMR data of 2 are as follows: 1 H NMR (600MHz, CDCl3): δ1.50 (sept, J = 7.5Hz, 3H), 1.27-1.20 (m, 18H).

[0067] (3) 2 (130 mg), tetrabutylammonium fluoride in THF solution (1 M, 1.56 mL), and THF (2 mL) were added sequentially to a 25 mL single-necked bottle. The mixture was reacted at room temperature in the dark for 10 minutes. 5 mL of water was added and the mixture was extracted three times with chloroform. The chloroform was removed by rotary evaporation under reduced pressure to obtain a yellow solid product 3 (62.2 mg, yield 95%). NMR data of 3: 1 H NMR (600MHz, CDCl3): δ9.08 (s, 1H).

[0068] (4) 3 (60 mg), Pd(PPh3)4 (22 mg), tributyl(4-(2-ethylhexyl)thiophen-2-yl)stannane (227 mg), anhydrous DMF (1 mL), and anhydrous toluene (1 mL) were added to a 10 mL Schlenck tube in sequence. The reaction was carried out at 110°C under nitrogen protection overnight. After cooling to room temperature, 5 mL of saturated sodium chloride aqueous solution was added and the mixture was extracted three times with petroleum ether. The organic layer was evaporated under reduced pressure and passed through a silica gel column using dichloromethane:petroleum ether (1:3) as the eluent to obtain a yellow waxy product 4 (130.4 mg, yield 92%). NMR data of 4: 1 H NMR (600MHz, CDCl3): δ8.89(s,1H),7.47(s,1H),7.02(s,1H),2.62(d,J=6.7Hz,2H),1.71-1.68(m,1H),1.38-1.24(m,8H),0.99-0.79(m,6H).

[0069] (5) 4 (130 mg), NBS (55.6 mg), and chloroform (5 mL) were added sequentially to a 25 mL single-necked bottle and reacted at room temperature in the dark for 4 hours. 5 mL of water was added and the mixture was extracted three times with chloroform. The chloroform was removed by rotary evaporation under reduced pressure and then passed through a silica gel column using chloroform:petroleum ether (1:8) as the eluent to obtain a yellow solid product 5 (115 mg, yield 73%). NMR data of 5: 1H NMR (600MHz, CDCl3): δ7.85 (s, 1H), 6.95 (s, 1H), 2.50 (d, J = 7.2Hz, 2H), 1.72-1.69 (m, 1H), 1.40-1.20 (m, 8H), 0.95-0.80 (m, 6H).

[0070] (6) 5 (40.9 mg), FBDT-SnMe3 (42.4 mg), Pd2(dba)3 (1.3 mg), P(o-tol)3 (2.7 mg), and anhydrous TL (0.95 mL) were added sequentially to a 10 mL Schlenck tube and reacted at 110°C under nitrogen for 24 hours. After cooling to room temperature, the reaction solution was added dropwise to 150 mL of methanol for chromatography to obtain a crude product. The crude product was then Soxhlet extracted with n-hexane, dichloromethane, and chloroform, respectively. The high molecular weight component was finally collected with hot chlorobenzene and gradually added dropwise to methanol to obtain a purple-red solid product P1 (36.8 mg, yield 64%). NMR data of P1: 1 H NMR(600MHz, CDCl3):7.43-7.14(br),4.20-2.61(br),2.28-0.69(br).

[0071] The polymer was dissolved in chloroform and spin-coated onto a quartz wafer. The thin film absorption spectra were measured using a Hitachi U-4100 UV-Vis scanning spectrophotometer. The solution absorption spectra were also measured using chloroform as the solvent. The normalized spectra are shown in Figure 7. The thin film absorption of the P1 polymer exhibits a 0-0 stacking peak that is higher than the 0-1 peak, indicating strong intermolecular stacking in the thin film state. The solution state also exhibits a strong aggregation peak, indicating that P1 forms a good pre-aggregation in the solution, which facilitates the formation of distinct phase separation when the mixed film is spin-coated.

[0072] Example 2: Synthesis of polymer P2

[0073]

[0074] (1) 5 (48.9 mg), FBDT-SnMe3 (51.4 mg), Pd2(dba)3 (1.6 mg), P(o-tol)3 (3.2 mg), and anhydrous toluene (1.05 mL) were added sequentially to a 10 mL Schlenck tube and reacted at 110°C under nitrogen for 24 hours. After cooling to room temperature, the reaction solution was added dropwise to 150 mL of methanol for chromatography to obtain a crude product. The product was then Soxhlet extracted with n-hexane, dichloromethane, and chloroform, respectively. The high molecular weight component was finally collected by chloroform and gradually added dropwise to methanol to obtain a red solid product P2 (45.6 mg, yield 75%).

[0075] The polymer was dissolved in chloroform and spin-coated onto a quartz wafer. The thin film absorption spectrum was measured using a Hitachi U-4100 UV-Vis scanning spectrophotometer. The solution absorption spectrum was also measured using chloroform as the solvent. The normalized spectra are shown in Figure 8. Compared to the fluorine-substituted P1 molecule, the chlorine-substituted P2 exhibits a weaker 0-0 thin film stacking peak and weaker solution-state preaggregation. This is attributed to the greater steric hindrance of the chlorine atom.

[0076] Example 3: Synthesis of polymer P3

[0077]

[0078] (1) 4,4'-dibromo-2,2'-bis(triisopropylsilyl)-5,5'-bithiazole (1.5 g), (2,5-diisooctylthiophene-3-yl)tributyltin (2.25 g), Pd(PPh3)4 (271 mg), and anhydrous DMF (30 mL) were added sequentially to a 100 mL Schlenck tube under nitrogen protection. The mixture was reacted at 110°C for 10 hours. After cooling to room temperature, 30 mL of saturated sodium chloride aqueous solution was added and the mixture was extracted three times with petroleum ether. The organic layer was evaporated under reduced pressure and passed through a silica gel column with dichloromethane:petroleum ether (1:7) as the eluent to obtain a yellow oily product 6 (712.6 mg, yield 35%).

[0079] (2) 6 (450 mg), palladium acetate (11.7 mg), tricyclohexylphosphine tetrafluoroborate (38.3 mg), cesium carbonate (339 mg), and anhydrous 1,4-dioxane (13 mL) were added sequentially to a 25 mL Schlenck tube. The reaction was carried out at 140°C under nitrogen protection overnight. After cooling to room temperature, 5 mL of saturated sodium chloride aqueous solution was added and the mixture was extracted three times with dichloromethane. The organic layer was evaporated under reduced pressure and passed through a silica gel column with dichloromethane:petroleum ether (1:4) as the eluent to obtain a yellow oily product 7 (187.8 mg, yield 46%).

[0080] (3) 7 (165 mg), tetrabutylammonium fluoride in THF solution (1 M, 1.56 mL), and THF (2 mL) were added sequentially to a 25 mL single-necked bottle. The mixture was reacted at room temperature in the dark for 10 minutes. 5 mL of water was added and the mixture was extracted three times with chloroform. The organic layer was evaporated under reduced pressure and passed through a silica gel column with dichloromethane as the eluent to obtain a yellow waxy product 8 (91.3 mg, 92% yield).

[0081] (4) 8 (236.4 mg), t-BuOK (224 mg), anhydrous THF (10 mL), and 2,3,4,5,6-pentafluoro-1-iodobenzene (323 mg) were added to a 25 mL Schlenck tube in sequence. The mixture was reacted at 0°C under nitrogen protection for 1 hour. The mixture was heated to room temperature and stirred for 2 hours. 5 mL of water was added, and the mixture was extracted three times with chloroform. The chloroform was removed by rotary evaporation under reduced pressure to obtain a yellow solid product 9 (351.2 mg, yield 97%).

[0082] (5) 9 (137.7 mg), Pd(PPh3)4 (22 mg), tributyl(thiophen-2-yl)stannane (212.7 mg), anhydrous DMF (1 mL), and anhydrous toluene (1 mL) were added to a 10 mL Schlenck tube in sequence. The mixture was reacted at 110°C under nitrogen for 4 hours. After cooling to room temperature, 5 mL of saturated sodium chloride aqueous solution was added and the mixture was extracted three times with petroleum ether. The organic layer was evaporated under reduced pressure and passed through a silica gel column with dichloromethane:petroleum ether (1:4) as the eluent to obtain a yellow waxy product 10 (112.6 mg, yield 93%).

[0083] (6) 10 (108.3 mg), NBS (55.6 mg), and chloroform (5 mL) were added sequentially to a 25 mL single-necked bottle and reacted at room temperature in the dark for 4 h. 5 mL of water was added and the mixture was extracted three times with chloroform. The chloroform was removed by rotary evaporation under reduced pressure and then passed through a silica gel column using chloroform:petroleum ether (1:8) as the eluent to obtain a yellow solid product 11 (109.5 mg, yield 81%).

[0084] (7) 11 (44.3 mg), FBDT-SnMe3 (52.4 mg), Pd2(dba)3 (1.5 mg), P(o-tol)3 (3.4 mg), and anhydrous toluene (0.90 mL) were added sequentially to a 10 mL Schlenck tube and reacted at 110°C under nitrogen for 24 h. After cooling to room temperature, the reaction solution was added dropwise to 150 mL of methanol for chromatography to obtain a crude product. The product was then Soxhlet extracted with n-hexane, dichloromethane, and chloroform, respectively. The high molecular weight component was finally collected by hot chlorobenzene and gradually added dropwise to methanol to obtain a purple-red solid product P5 (44 mg, yield 62%).

[0085] Example 4: Preparation of an organic solar cell based on the donor material P1 of Example 1

[0086] A PEDOT:PSS solution was spin-coated on a clean conductive glass (ITO) substrate and heated at 150°C for 10 minutes. The PEDOT:PSS thickness was 30 nm. The polymer donor material P1 obtained in Example 1 and the non-fullerene acceptor material L8BO were dissolved in chloroform at a weight ratio of 1:1.4. The concentration of the solution based on the donor material P1 was 5.3 mg / mL. The solution was spin-coated on the PEDOT:PSS film as an active layer with a thickness of 100 nm. A PDINN solution was spin-coated on the active layer. Ag was evaporated onto the surface of the PDINN with a thickness of 80 nm to obtain the organic solar cell (see Figure 9 ). Among them, ITO (Indium Tin Oxides) is the abbreviation of indium tin oxide, which serves as the anode of the organic solar cell in the embodiment; PEDOT:PSS is an aqueous solution of a high molecular polymer composed of two substances, PEDOT and PSS. PEDOT is a polymer of EDOT (3,4-ethylenedioxythiophene monomer), and PSS is polystyrene sulfonate; PDINN is the abbreviation of N,N'-bis{3-[3-(dimethylamino)propylamino]propyl}piperene-3,4,9,10-tetracarboxylic acid diimide, which serves as the electron transport layer.

[0087] The photovoltaic performance of the polymer was characterized using a Keithley 2400 SourceMeter and a Xenon-lamp-based solar simulator. 2 Under the same light intensity, the open circuit voltage of the P1-based photovoltaic device is 0.901V and the short circuit current density is 27.01mA / cm 2 , the fill factor is 78.90%, the energy conversion efficiency is 19.21%, and the current-voltage curve (JV curve) of the solar cell of the corresponding device is as follows Figure 10 The external quantum efficiency spectrum was obtained by the QE-R3011 Enli Tech test system, and the integrated current obtained by integrating the response curve was 25.75 mA / cm 2 , which is less than 5% of the test result of (JV curve) (see Figure 11 ).

[0088] The applicant states that the present invention is intended to illustrate the detailed methods of the present invention through the above-described embodiments, but the present invention is not limited to the above-described detailed methods, that is, it does not mean that the present invention must rely on the above-described detailed methods in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for various raw materials in the products of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

Claims

1. A polymer material based on dithiazolylbenzothiophene structural units, characterized by: The polymer material has a molecular structure as shown in formula (I): Formula (I) Where, A is selected from any one of the following structures: ； D is selected from any one of the following structures: ； X is H, F or Cl; R1, R2, R3 can be the same or different and can be selected from hydrogen, halogen, hydroxyl, C1-C 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Silane groups, C1-C 20 Alkylthio, C2-C 20 Alkenyl, C2-C 20 Alkynyl; unsubstituted or replaced by at least one C1-C 20 an alkyl-substituted amino, aryl or heteroaryl group; a and b may be the same or different and are natural numbers from 0 to 2, and n represents the degree of polymerization and is a natural number between 2 and 1000.

2. The polymer material based on dithiazolylbenzothiophene structural units according to claim 1, characterized in that: The polymer is of the formula, A is selected from any one of the following structures: ； D is selected from any one of the following structures: ； X is H, F or Cl; R1, R2, R3 can be the same or different and can be selected from hydrogen, halogen, hydroxyl, C1-C 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Silane groups, C1-C 20 Alkylthio, C2-C 20 Alkenyl, C2-C 20 Alkynyl; unsubstituted or replaced by at least one C1-C 20 an alkyl-substituted amino group, a phenyl group, or a thienyl group; a and b may be the same or different and are natural numbers from 0 to 2, and n represents the degree of polymerization and is a natural number between 2 and 1000.

3. The polymer material based on dithiazolylbenzothiophene structural units according to claim 2, characterized in that: The polymer is of the formula, Where, A is selected from any one of the following structures: ； D is selected from any one of the following structures: ； X is H, F or Cl; R1, R2, R3 can be the same or different and can be selected from hydrogen, halogen, hydroxyl, C1-C 20 Alkyl, C1-C 20 Alkoxy, C1-C 20 Silane groups, C1-C 20 Alkylthio, C2-C 20 Alkenyl, C2-C 20 unsubstituted or substituted by at least one C1-C8 alkyl group, phenyl or thienyl; a and b may be the same or different and are natural numbers from 0 to 2, and n represents the degree of polymerization and is a natural number between 2 and 1000.

4. A method for preparing a polymer material based on dithiazolylbenzothiophene structural units according to claim 1, characterized in that: A monomer containing a dithiazolylbenzothiophene structure is mixed with a monomer containing a unit D, and a polymerization reaction is carried out under the catalysis of a catalyst. A polymer donor material having a dithiazolylbenzothiophene structure shown in formula (I) is obtained by purification and separation.

5. The method for preparing a polymer material based on dithiazolylbenzothiophene structural units according to claim 4, characterized in that: The catalyst is a palladium catalyst; the molar ratio of monomer A based on dithiazobenzothiophene structure to monomer D is equal to 1.

6. The method for preparing a polymer material based on dithiazolylbenzothiophene structural units according to claim 4, characterized in that: The polymerization reaction temperature is 80-150° C., and the solvent used is toluene and / or N,N-dimethylformamide. When toluene and N,N-dimethylformamide are mixed, the volume ratio is 0-1.

7. An application of the polymer material based on dithiazolylbenzothiophene structural units according to claim 1, characterized in that: The polymer is used as an electron donor material in an organic optoelectronic device.

8. An organic solar cell device comprising a substrate, an anode, an anode modification layer, a photoactive layer, a cathode modification layer, and a cathode, characterized in that: The photoactive layer is a thin film formed by mixing a polymer donor and an acceptor, and the polymer donor is the polymer material according to claim 1.

Images