Benzodithiophene-4, 8-diketone-based ternary donor polymer with wide optical band gap and preparation method of benzodithiophene-4, 8-diketone-based ternary donor polymer

Abstract

The invention relates to the field of polymer solar cells, and particularly discloses a benzodithiophene-4, 8-diketone-based ternary donor polymer with a wide optical band gap and a preparation method of the benzodithiophene-4, 8-diketone-based ternary donor polymer. The ternary donor polymer is prepared by taking 2 (4, 8-bis (5-(2-ethylhexyl)-4-fluorothiophene-2-yl) benzo [1, 2-b: 4, 5-b '] dithiophene-2, 6-diyl) bis (trimethylstannane), bis (2-butyl octyl) 4, 8-bis (5-bromothiophene-2-yl) benzo [1, 2-b: 4, 5-b'] dithiophene-2, 6-diformate and a benzodithiophene-4, 8-diketone derivative as raw materials through a one-step reaction. The polymer is prepared through Stille coupling ternary random polymerization reaction, the optical band gap of the polymer is 1.86-1.90 eV and is higher than that of a classic donor polymer PM6, and an effective thought is provided for developing a novel donor polymer with excellent performance and high conversion efficiency.

Description

Technical Field

[0001] The present application relates to the field of polymer solar cells, in particular, to the field of organic optoelectronic functional materials, and more particularly, to a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap and a preparation method thereof. Background Art

[0002] In today's era of popularization and development of new energy, how to efficiently utilize existing energy and reduce excess energy loss has gradually become the most talked-about topic. Among them, solar energy accounts for a very high proportion of available energy, so designing and improving the optimization of solar cells to further improve the efficiency of energy acquisition has become the focus of photovoltaic researchers and major research groups. Since the development of solar cells, although there have been certain research results, the leader in the relevant field is still silicon-based solar cells. Silicon-based solar cells themselves have difficult-to-solve defects, such as high preparation process cost and large volume share, so it is difficult to be widely used. The corresponding polymer solar cells (PSCs) take into account the advantages of flexible structure and low cost, and have less harm to the environment, showing a strong industrialization prospect. The development of PSCs has undergone a transition from fullerene to non-fullerene. At present, the highest photoelectric conversion efficiency (PCE) of laboratory PSCs has reached 18.6%. At present, in the stage where non-fullerene is the mainstream electron acceptor, in order to compensate for the optical absorption of bulk heterojunction solar cells at short wavelengths, wide-bandgap donor polymers have become the mainstream of design.

[0003] In recent years, PM6, as the main wide bandgap polymer, the efficiency of its related devices is being continuously optimized. Specifically, PM6 is a very classic donor polymer material based on benzodithiophene-4,8-dione, which is polymerized from benzodithiophene-4,8-dione (BDD) and 2(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane) (BDTF) as raw materials. Since its birth, PM6 has shown great potential. Its suitable band gap (1.84eV), absorption range and excellent photovoltaic performance have made it a research hotspot. For example, in 2017, Hou Jianhui and others achieved a PCE of 9.2% in the devices prepared with it. After the emergence of the high-efficiency acceptor material Y6, the device based on PM6:Y6 achieved a PCE of 15.7%, which was the highest efficiency of binary PSCs at the time. After continuous optimization, the device based on PM6 further achieved a PCE of nearly 18%.

[0004] However, with the emergence of more high-performance acceptor materials, the existing donor materials are far from meeting the matching requirements. Therefore, it is very necessary to optimize the molecular structure of the donor material, adjust the photoelectric properties of the donor material, and further improve the photovoltaic performance of the device. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap and a preparation method thereof. By introducing bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate, an effective electron-withdrawing structural unit, a ternary donor polymer with a wide band gap is conducted and constructed, and its optical band gap can be widened to 1.86-1.90 eV, providing new ideas and structural choices for regulating the performance of existing donor polymer materials.

[0006] In the first aspect, the present application provides a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap, which adopts the following technical solution: A ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap, the structural formula of which is shown below: Among them, 0<n<1, m=1-n.

[0007] Preferably, the optical band gap of the ternary donor polymer is 1.86-1.90 eV.

[0008] By adopting the above-mentioned technical scheme, the ternary donor polymer based on benzodithiophene-4,8-dione of the present application introduces a bis(2-butyloctyl)-4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate (VBDTC) unit into the main chain of the classic donor polymer PM6, and utilizes the weak electron-withdrawing property of the VBDTC unit to achieve the purpose of broadening the optical band gap of the donor polymer. The optical band gap of the ternary donor polymer can be broadened to 1.86-1.90 eV. Specifically, firstly, since the side chain of the VBDTC unit contains two electron-withdrawing unsaturated ester bonds, the polymer is endowed with a certain electron-withdrawing ability after the polymer is formed, which will interact with the π electron cloud on the polymer main chain, resulting in an increase in the energy level gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), that is, the band gap becomes wider; secondly, charge transfer may occur between the introduced third component VBDTC and the polymer main chain, and this transfer can increase the charge separation of the system, resulting in a widening of the optical band gap. In addition, the ternary donor polymer of the present application is easily soluble in common organic solvents such as chloroform, so a spin coating method can be used to prepare a thin film for related tests, which is simple and easy to operate.

[0009] In the second aspect, the present application provides a method for preparing a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap, which adopts the following technical scheme: A method for preparing a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap comprises the following steps: S1. Under the protection of an inert gas, using dry toluene as a solvent, a raw material is subjected to a Stille coupling ternary random polymerization reaction under the catalytic action of a catalyst; the raw material includes 2(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane), bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate and a benzodithiophene-4,8-dione derivative; the catalyst includes tri(o-methylphenyl)phosphine and trisdibenzylideneacetone dipalladium; S2. Purify the product obtained in step S1 by column chromatography, precipitation and Soxhlet extraction in sequence, and obtain the ternary donor polymer after drying.

[0010] Preferably, the mass ratio of toluene to raw material is (30-50):1.

[0011] Preferably, the molar ratio of the 2(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane), bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate and benzodithiophene-4,8-dione derivative is 1:(1-n):n, wherein 0<n<1.

[0012] Preferably, the amount of the catalyst used is 1-5% of the total mass of the raw materials.

[0013] Preferably, the temperature range of the Stille coupling ternary random polymerization reaction is 100-110° C., and the reaction time is 1-3 h.

[0014] Preferably, the developing solvent used in the column chromatography method is chloroform.

[0015] Preferably, the good solvent and the poor solvent used in the precipitation method are chloroform and methanol respectively.

[0016] Preferably, the solvent used in the Soxhlet extraction method is petroleum ether, acetone, ethyl ether and dichloromethane.

[0017] By adopting the above technical scheme, the present application uses bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate (VBDTC), benzodithiophene-4,8-dione derivative (BDD) and (4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane) (BDTF) as raw materials, and after Stille coupling ternary random polymerization reaction, purification is carried out in sequence by column chromatography, precipitation method and Soxhlet extraction method to prepare a ternary donor polymer. The preparation method of the present application has a simple synthesis route. Through the Stille coupling ternary random polymerization reaction, the raw materials participate in the polymerization to obtain the target polymer, and the post-processing is simple, which is conducive to reducing the cost of synthesis and has good application prospects.

[0018] The structural formula of bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate (VBDTC) of the present application is: The structural formula of the benzodithiophene-4,8-dione derivative (BDD) of the present application is: The structural formula of (4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane) of the present application is:

[0019] The synthetic route of the present application is as follows:

[0020] In summary, this application has the following beneficial technical effects: 1. The ternary donor polymer based on benzodithiophene-4,8-dione of the present application introduces a bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate (VBDTC) unit into the main chain of the classic PM6 donor polymer, which widens the optical band gap of the donor polymer to 1.86-1.90 eV, further improving the photovoltaic performance of the device; 2. The ternary donor polymer based on benzodithiophene-4,8-dione of the present application is easily soluble in common organic solvents such as chloroform, so the spin coating method can be used to prepare thin films for related tests, which is simple and easy to operate; 3. The preparation method of the ternary donor polymer based on benzodithiophene-4,8-dione of the present application has a simple synthesis route. Through the Stille coupling ternary random polymerization reaction, the target polymer can be obtained by the participation of the raw materials in the polymerization, and the post-processing is simple, which is conducive to reducing the cost of synthesis and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The ultraviolet absorption spectrum of the ternary donor polymer prepared in Example 1 of the present application; Figure 2 The ultraviolet absorption spectrum of the ternary donor polymer prepared in Example 2 of the present application; Figure 3 The ultraviolet absorption spectrum of the ternary donor polymer prepared in Example 3 of the present application; Figure 4 This is the ultraviolet absorption spectrum of the donor polymer PM6. DETAILED DESCRIPTION

[0022] Unless otherwise specified, the raw materials used in this application are all commercially available products.

[0023] In some embodiments of the benzodithiophene-4,8-dione-based ternary donor polymer with a wide optical band gap, the mass ratio of toluene to the raw material is (30-50):1; In some embodiments of the ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap, the molar ratio of the three raw materials, 2(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane), bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate and benzodithiophene-4,8-dione derivative, is 1:(1-n):n, wherein 0<n<1; In some embodiments of the ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap, the amount of the catalyst is 1-5% of the total weight of the raw materials; In some embodiments of the benzodithiophene-4,8-dione-based ternary donor polymer having a wide optical band gap, the developing solvent used in the column chromatography method is chloroform; In some embodiments of the benzodithiophene-4,8-dione-based ternary donor polymer with a wide optical band gap, the good solvent and the poor solvent used in the precipitation method are chloroform and methanol, respectively; In some embodiments of the benzodithiophene-4,8-dione-based ternary donor polymer with a wide optical band gap, the solvent used in the Soxhlet extraction method is petroleum ether, acetone, diethyl ether and dichloromethane; In some specific embodiments of ternary donor polymers based on benzodithiophene-4,8-dione with a wide optical band gap, the above substances and proportions are used, and the following method is used: under the protection of an inert gas, using dry toluene as a solvent, 2(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane), bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl) 6-dicarboxylic acid ester and benzodithiophene-4,8-dione derivatives were subjected to Stille coupling ternary random polymerization reaction at 100-110°C under the co-catalyzed action of tri(o-methylphenyl)phosphine and tridibenzylideneacetone dipalladium. The reaction time was 1-3h. After purification and drying by column chromatography, precipitation and Soxhlet extraction, the optical band gap of the obtained ternary donor polymer was widened to 1.86-1.90eV, which was larger than the optical band gap of 1.84eV of PM6 donor polymer, further improving the photovoltaic performance of the device.

[0024] The applicant further uses the following three examples to verify the optical band gap of the ternary donor polymer based on benzodithiophene-4,8-dione prepared by the preparation method of the present application.

[0025] Example 1 A method for preparing a ternary donor polymer PBDTF (0.1) based on benzodithiophene-4,8-dione with a wide optical band gap comprises the following steps: S1. Under nitrogen protection, bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate (9.341 mg, 0.01 mmol), benzodithiophene-4,8-dione derivative (68.761 mg, 0.09 mmol), 2(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethyltinane) (94.21 mg, 0.1 mmol), catalyst tridibenzylideneacetone dipalladium (6 mg), tri(o-methylphenyl)phosphine (1.3 mg) and 6 mL of toluene were added into a reaction vessel, and the mixture was refluxed at 110° C. for 1 h until the reaction system became viscous. S2. The product obtained in step S1 was preliminarily purified by column chromatography using chloroform as a solvent, and then the product was poured into anhydrous methanol (100 mL) for precipitation. The solid after filtration was subjected to Soxhlet extraction to separate low molecular weight oligomers for further purification. Petroleum ether, acetone, ether and dichloromethane were used as extractants in sequence, and finally vacuum dried to obtain 153.3 mg of a reddish brown solid, which was a ternary donor polymer PBDTF (0.1) based on benzodithiophene-4,8-dione with a wide optical band gap.

[0026] The synthetic route is as follows:

[0027] Example 2 A method for preparing a ternary donor polymer PBDTF (0.2) based on benzodithiophene-4,8-dione with a wide optical band gap comprises the following steps: S1. Under nitrogen protection, bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate (18.683 mg, 0.02 mmol), benzodithiophene-4,8-dione derivative (61.121 mg, 0.08 mmol), 2(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane) (94.21 mg, 0.1 mmol), catalyst tridibenzylideneacetone dipalladium (6 mg), tri(o-methylphenyl)phosphine (1.3 mg) and 6 mL of toluene were added into a reaction vessel, and the mixture was refluxed at 110° C. for 1 h until the reaction system became viscous. S2. The product obtained in step S1 was preliminarily purified by column chromatography using chloroform as a solvent, and then the product was poured into anhydrous methanol (100 mL) for precipitation. The solid after filtration was subjected to Soxhlet extraction to separate low molecular weight oligomers for further purification. Petroleum ether, acetone, ether and dichloromethane were used as extractants in sequence, and finally vacuum dried to obtain 140.6 mg of a reddish brown solid, which was a ternary donor polymer PBDTF (0.2) based on benzodithiophene-4,8-dione with a wide optical band gap.

[0028] The synthetic route is as follows:

[0029] Example 3 A method for preparing a ternary donor polymer PBDTF (0.3) based on benzodithiophene-4,8-dione with a wide optical band gap comprises the following steps: S1. Under nitrogen protection, bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate (28.02 mg, 0.03 mmol), benzodithiophene-4,8-dione derivative (53.48 mg, 0.07 mmol), 2(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethyltinane) (94.21 mg, 0.1 mmol), catalyst tridibenzylideneacetone dipalladium (6 mg), tri(o-methylphenyl)phosphine (1.3 mg) and 6 mL of toluene were added into a reaction vessel, and the mixture was refluxed at 110° C. for 1 h until the reaction system became viscous. S2. The product obtained in step S1 was preliminarily purified by column chromatography using chloroform as a solvent, and then the product was poured into anhydrous methanol (100 mL) for precipitation. The solid after filtration was subjected to Soxhlet extraction to separate low molecular weight oligomers for further purification. Petroleum ether, acetone, ether and dichloromethane were used as extractants in sequence, and finally vacuum dried to obtain 127.5 mg of a reddish brown solid, which was a ternary donor polymer PBDTF (0.3) based on benzodithiophene-4,8-dione with a wide optical band gap.

[0030] The synthetic route is as follows:

[0031] Performance Testing 1. The UV-visible absorption spectrum of the polymer prepared in Example 1 in chloroform solution at room temperature was obtained by using a Perkin-Elmer Lambda 25 spectrophotometer. The results are as follows: Figure 1 shown.

[0032] from Figure 1 From the analysis, we can know that the target product PBDTF (0.1) has ultraviolet absorption in the wavelength range of 400nm-675nm; and it can be observed that there are two groups of absorption peaks in this range, namely at a wavelength of 560nm and a wavelength of 610nm. Among them, the intensity of the absorption peak at a wavelength of 610nm is higher than that at a wavelength of 560nm, and has a maximum absorbance of A = 0.18au. In addition, its initial absorption wavelength (λ onset ) is 665nm, according to formula E g opt =1240 / λ edge The calculated optical band gap of PBDTF(0.1) is 1.86eV, which is larger than 1.84eV of PM6.

[0033] 2. The UV-visible absorption spectrum of the polymer prepared in Example 2 in chloroform solution at room temperature was measured using a Perkin-Elmer Lambda 25 spectrophotometer. The results are as follows: Figure 2 shown.

[0034] from Figure 2 From the analysis, we can know that the target product PBDTF (0.2) has ultraviolet absorption in the wavelength range of 400nm-675nm; and it can be observed that there are two groups of absorption peaks in this range, namely at a wavelength of 560nm and a wavelength of 595nm. Among them, the intensity of the absorption peak at a wavelength of 560nm is higher than that at a wavelength of 595nm, and the maximum absorbance A = 0.14au. In addition, its initial absorption wavelength (λ onset ) is 662nm, according to formula Eg opt =1240 / λ edge The calculated optical band gap of PBDTF(0.2) is 1.87eV, which is larger than 1.84eV of PM6.

[0035] 3. The UV-visible absorption spectrum of the polymer prepared in Example 3 in chloroform solution at room temperature was measured using a Perkin-Elmer Lambda 25 spectrophotometer. The results are as follows: Figure 3 shown.

[0036] from Figure 3 From the analysis, we can know that the target product PBDTF (0.3) has ultraviolet absorption in the wavelength range of 410nm-650nm; and it can be observed that there is only one set of absorption peaks in this range, that is, the highest absorption peak at a wavelength of 505nm, and the maximum absorbance A = 0.025au. In addition, its initial absorption wavelength (λ onset ) is 651nm, according to formula E g opt =1240 / λ edge The calculated optical band gap of PBDTF(0.3) is 1.90eV, which is larger than 1.84eV of PM6.

[0037] Therefore, it can be seen from the above test results that the ternary donor polymer based on benzodithiophene-4,8-dione prepared by introducing bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate units in the present application has a wide optical band gap, which can reach 1.86-1.90 eV, which is larger than 1.84 eV ( Figure 4 ), which provides a new idea and structural choice for regulating the performance of existing donor polymer materials. The use of the ternary donor polymer of this application can further improve the optical performance of the device and has extremely broad application prospects.

[0038] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap, characterized in that The structural formula is as follows: Among them, 0<n<1, m=1-n.

2. A ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap according to claim 1, characterized in that: The optical band gap of the ternary donor polymer is 1.86-1.90 eV.

3. A method for preparing a ternary donor polymer based on benzodithiophene-4,8-dione having a wide optical band gap as claimed in claim 2, characterized in that: The following steps are involved: S1. Under the protection of an inert gas, using dry toluene as a solvent, a raw material is subjected to a Stille coupling ternary random polymerization reaction under the catalytic action of a catalyst; the raw material includes 2(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane), bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate and a benzodithiophene-4,8-dione derivative; the catalyst includes tri(o-methylphenyl)phosphine and trisdibenzylideneacetone dipalladium; S2. Purify the product obtained in step S1 by column chromatography, precipitation and Soxhlet extraction in sequence, and obtain the ternary donor polymer after drying.

4. The method for preparing a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap according to claim 3, characterized in that: The mass ratio of toluene to raw material is (30-50):

1.

5. The method for preparing a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap according to claim 3, characterized in that: The molar ratio of the 2(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane), bis(2-butyloctyl)4,8-bis(5-bromothiophene-2-yl)benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate and benzodithiophene-4,8-dione derivative is 1:(1-n):n, wherein 0<n<1.

6. The method for preparing a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap according to claim 3, characterized in that: The amount of the catalyst used is 1-5% of the total mass of the raw materials.

7. The method for preparing a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap according to claim 3, characterized in that: The temperature range of the Stille coupling ternary random polymerization reaction is 100-110° C., and the reaction time is 1-3 hours.

8. The method for preparing a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap according to claim 3, characterized in that: The developing solvent used in the column chromatography method is chloroform.

9. The method for preparing a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap according to claim 3, characterized in that: The good solvent and the poor solvent used in the precipitation method are chloroform and methanol respectively.

10. The method for preparing a ternary donor polymer based on benzodithiophene-4,8-dione with a wide optical band gap according to claim 3, characterized in that: The solvents used in the Soxhlet extraction method are petroleum ether, acetone, ether and dichloromethane.

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