An organic photovoltaic polymer donor material, process of preparation and use

Abstract

The present application relates to an organic photovoltaic polymer donor material, a preparation process and application, and belongs to the technical field of polymer photovoltaic materials. Three organic photovoltaic polymer donor materials with different molecular weights and narrow distribution are prepared by optimizing the post-treatment process of the crude product of the organic photovoltaic polymer donor material. By selecting a plurality of solvents with branching and steric hindrance for compounding, the polarity, steric hindrance effect and branching effect of the solvents are utilized to realize efficient separation of the three organic photovoltaic polymer donor materials with different molecular weights. The organic photovoltaic polymer donor material prepared by the present application has good photoelectric conversion efficiency, and the photoelectric conversion efficiency of the low-molecular-weight, medium-molecular-weight and high-molecular-weight organic photovoltaic polymer donor materials is higher than that of the organic photovoltaic polymer donor material without separation and purification.

Description

Technical Field

[0001] This invention relates to an organic photovoltaic polymer donor material, its preparation process, and its application, belonging to the field of polymer photovoltaic materials technology. Background Technology

[0002] Organic solar cells typically consist of a transparent conductive substrate, a photoactive layer, a metal electrode, and an interface modification layer. The transparent conductive substrate is usually indium tin oxide (ITO)-supported glass or flexible PET. The photoactive layer is the core of the device, where most of the physical processes that convert light energy into electrical energy occur. The most commonly used metal electrodes are aluminum, silver, and gold. The working principle of organic solar cells can be summarized as light absorption and exciton generation, exciton diffusion, exciton dissociation, carrier transport, and charge collection. Energy conversion efficiency is the most direct indicator of the performance of organic solar cells.

[0003] The development of donor and acceptor materials in the active layer is one of the most important factors driving the development of organic solar cells. Benzodithiophene, with its wide absorption range, good hole mobility, and deep HOMO level, is a widely used structural unit for polymer donor materials. For example, the paper "Synthesis and Photovoltaic Performance Study of Polymer Donor Materials Based on Benzodithiophene Framework" uses diester-substituted thiophene as the electron-withdrawing unit and benzodithiophene as the electron-donating unit, copolymerizing them to obtain a polymer donor material. The influence of side chain length on the photovoltaic performance of diester-substituted trithiophene-benzodithiophene polymers was studied. However, the dispersion coefficient (PDI) of the polymer donor material synthesized in this paper is relatively large, affecting the improvement of its photovoltaic performance. Summary of the Invention

[0004] The purpose of this invention is to provide an organic photovoltaic polymer donor material, its preparation process, and its application, in order to solve the problem that the high dispersion coefficient (PDI) of current polymer donor materials affects the improvement of their photovoltaic performance.

[0005] This invention provides a preparation process for an organic photovoltaic polymer donor material, comprising the following steps: a dibromothiophene ester compound and an organotin compound undergo a Stille coupling reaction in toluene to obtain an organic photovoltaic polymer donor material solution; the organic photovoltaic polymer donor material solution is then mixed with solvent A1 and subjected to a first centrifugation separation, the solid a obtained from the first centrifugation separation being the crude organic photovoltaic polymer donor material; then, solid a and solvent B are heated and ultrasonically dispersed, followed by a second centrifugation separation; the liquid b obtained from the second centrifugation separation is heated and mixed with solvent A2, followed by a third centrifugation separation; the solid obtained from the third centrifugation separation is dried to obtain a low molecular weight organic photovoltaic polymer donor material; the solid b obtained from the second centrifugation separation is heated and mixed with the mixed solvent, followed by a fourth centrifugation separation; the solid b obtained from the fourth centrifugation separation is dried... The liquid c obtained from centrifugation is mixed with solvent A3 and then subjected to a fifth centrifugation. The solid obtained from the fifth centrifugation is dried to obtain a medium molecular weight organic photovoltaic polymer donor material. The solid c obtained from the fourth centrifugation is dried to obtain a high molecular weight organic photovoltaic polymer donor material. Solvent A1 is methanol, solvent A2 is composed of ethanol and tert-butanol in a volume ratio of 3~5:1~2, solvent A3 is composed of ethanol and 2-methyl-2-butanol in a volume ratio of 3~5:2~3, solvent B is composed of n-hexane and isooctane in a volume ratio of 6~7:2~3, the mixed solvent is composed of solvent C and solvent D in a volume ratio of 1:1~3, solvent C is composed of acetone and methyl tert-butyl ketone in a volume ratio of 5~8:3~4, and solvent D is xylene. The structure of the dibromobisthiophene ester compound is as follows: ;

[0006] The structure of the organotin compound is as follows: .

[0007] Preferably, the volume ratio of the organic photovoltaic polymer donor material solution to solvent A1 is 1:1~3.

[0008] Preferably, the solid a and solvent B are ultrasonically dispersed at a temperature of 35~40℃ for 60~100min.

[0009] Preferably, the mass ratio of solid a to solvent B is 1:20~30.

[0010] Preferably, the temperature at which the liquid b obtained from the second centrifugation is heated and mixed with solvent A2 is 50~60℃, and the time is 30~60min.

[0011] Preferably, the volume ratio of liquid b to solvent A2 is 1:5~8.

[0012] Preferably, the solid b obtained from the second centrifugation and the mixed solvent are heated and mixed at a temperature of 50~55℃ for 90~180 min; the mass ratio of solid b to mixed solvent is 1:10~15.

[0013] Preferably, the volume ratio of liquid c obtained from the fourth centrifugation to solvent A3 is 1:3~5.

[0014] This invention provides an organic photovoltaic polymer donor material having the following structure: ;

[0015] The organic photovoltaic polymer donor material has a number-average molecular weight of 10008~10021 and a dispersion coefficient of 1.05~1.10; or a number-average molecular weight of 13854~13917 and a dispersion coefficient of 1.08~1.11; or a number-average molecular weight of 17384~17462 and a dispersion coefficient of 1.07~1.10.

[0016] This invention provides an application of the organic photovoltaic polymer donor material described above in organic solar cells.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: The preparation process of the organic photovoltaic polymer donor material of this invention, through monomer synthesis, polymerization reaction, and post-reaction treatment, yields three organic photovoltaic polymer donor materials with different molecular weights. The low molecular weight organic photovoltaic polymer donor material has a number average molecular weight of 10008~10021 and a dispersion coefficient (PDI) of 1.02~1.06; the medium molecular weight organic photovoltaic polymer donor material has a number average molecular weight of 13854~13917 and a PDI of 1.04~1.06; and the high molecular weight organic photovoltaic polymer donor material has a number average molecular weight of 17384~17462 and a PDI of 1.04~1.07. The total yield of the three organic photovoltaic polymer donor materials with different molecular weights is greater than 95%. This invention prepares three organic photovoltaic polymer donor materials with narrow molecular weight distributions by optimizing the post-processing process of the crude organic photovoltaic polymer donor material. By using a combination of solvents with branching and steric hindrance properties, and leveraging the polarity, steric hindrance, and branching effects of the solvents, efficient separation of three organic photovoltaic polymer donor materials with different molecular weights is achieved. The organic photovoltaic polymer donor materials prepared by this invention exhibit good photoelectric conversion efficiency. The photoelectric conversion efficiency of low-molecular-weight, medium-molecular-weight, and high-molecular-weight organic photovoltaic polymer donor materials is higher than that of unseparated and purified organic photovoltaic polymer donor materials, and the photoelectric conversion efficiency of high-molecular-weight organic photovoltaic polymer donor materials is higher than that of low-molecular-weight and medium-molecular-weight organic photovoltaic polymer donor materials. Attached Figure Description

[0018] Figure 1 The 1H NMR spectrum of the dibromothiophene ester compound prepared in Example 1 of this invention;

[0019] Figure 2 The 1H NMR spectrum of the bithiophene ester compound prepared in Example 1 of this invention;

[0020] Figure 3 The 1H NMR spectrum of the dibromobisthiophene ester compound prepared in Example 1 of this invention;

[0021] Figure 4 This is a schematic diagram of the process for separating and purifying polymer donor materials of different molecular weights in Example 1 of the present invention. Detailed Implementation

[0022] The following examples are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the present invention.

[0023] I. Specific embodiments of the preparation process of the organic photovoltaic polymer donor material of the present invention are as follows:

[0024] Example 1

[0025] The preparation process of the organic photovoltaic polymer donor material in this embodiment includes the following steps:

[0026] (1) 2,5-Dibromothiophene-3,4-dicarboxylic acid and sulfonium chloride in a molar ratio of 1:13 were added to a reaction vessel, heated to 80°C, stirred and refluxed for 6 h, and then distilled under reduced pressure to remove unreacted sulfonium chloride, yielding 2,5-dibromothiophene-3,4-diacyl chloride; then 2,5-dibromothiophene-3,4-diacyl chloride and anhydrous tetrahydrofuran in a mass ratio of 1:2 were added to the reaction vessel, stirred evenly, and then 4-isopropylcyclohexanol (the molar ratio of 4-isopropylcyclohexanol and 2,5-dibromothiophene-3,4-diacyl chloride was 6:1) was added, heated to 75°C, stirred and refluxed for 12 h, and then distilled under reduced pressure to remove the solvent, yielding a crude product. The crude product was purified by column chromatography using ethyl acetate, petroleum ether, and dichloromethane in a volume ratio of 3:1:1 to obtain a dibromothiophene alcohol ester compound (pale yellow solid). The 1H NMR spectrum of the dibromothiophene alcohol ester compound is shown below. Figure 1 As shown, the chemical structure is as follows: .

[0027] (2) A mixture of dibromothiophene ester, 2-(tributyltinyl)thiophene, tetra(triphenylphosphine)palladium, and anhydrous toluene in a molar ratio of 1:3:0.1:180 was added to a reaction vessel. Argon gas was then introduced, and the mixture was stirred until homogeneous. The mixture was then heated to 105°C and stirred for 20 hours. The solvent was removed by vacuum distillation to obtain a crude product. The crude product was purified by column chromatography using ethyl acetate, petroleum ether, and dichloromethane in a volume ratio of 4:1:1 to obtain a bithiophene ester (yellow solid). The 1H NMR spectrum of the bithiophene ester is shown below. Figure 2 As shown, the chemical structure is as follows: .

[0028] (3) Add the bithiophene ester compound and anhydrous tetrahydrofuran in a mass ratio of 1:50 to the reaction vessel and stir until the bithiophene ester compound is fully dissolved. Then, add a 60% (w / w) tetrahydrofuran solution of N-bromosuccinimide to the reaction vessel dropwise. Stir the reaction at room temperature for 20 h. After the reaction is complete, add water and dichloromethane to the reaction vessel, stir evenly, and allow it to stand for phase separation. Separate the organic phase and distill under reduced pressure to obtain the crude product. Purify the crude product by column chromatography using ethyl acetate, petroleum ether, and dichloromethane in a volume ratio of 4:1:1 to obtain the dibromobithiophene ester compound (yellow solid). The molar ratio of the bithiophene ester compound to N-bromosuccinimide is 1:2.2. The 1H NMR spectrum of the dibromobithiophene ester compound is shown below. Figure 3 As shown, the chemical structure is as follows: .

[0029] (4) A dibromobisthiophene ester compound, an organotin compound, tetrakis(triphenylphosphine)palladium, and toluene in a molar ratio of 1:1:0.1:30 were added to a reaction vessel. Argon gas was then introduced into the reaction vessel, and after stirring until homogeneous, the mixture was heated to 115°C and stirred for 30 hours. The mixture was then cooled to room temperature to obtain an organic photovoltaic polymer donor material solution. The chemical structure of the organotin compound is as follows: .

[0030] (5) such as Figure 4 As shown, the organic photovoltaic polymer donor material solution and solvent A1 were added to a stirred tank at a volume ratio of 1:1. After stirring at room temperature for 30 minutes, a first centrifugation was performed. The solid a obtained from the first centrifugation was the crude organic photovoltaic polymer donor material, and the liquid a obtained from the first centrifugation was the waste liquid. Then, solid a and solvent B were added to the stirred tank at a mass ratio of 1:20. The mixture was heated to 35°C, ultrasonically dispersed for 80 minutes, and then a second centrifugation was performed. The liquid b obtained from the second centrifugation and solvent A2 were mixed at a volume ratio of 1:5 at 50°C for 30 minutes and then a third centrifugation was performed. The solid obtained from the third centrifugation was dried to obtain the low molecular weight organic photovoltaic polymer donor material.

[0031] The solid b obtained from the second centrifugation and a mixed solvent consisting of solvents C and D in a volume ratio of 1:1 were added to a stirred tank at a mass ratio of 1:10. After heating to 50°C and stirring for 130 min, a fourth centrifugation was performed. The liquid c obtained from the fourth centrifugation and solvent A3 were mixed at a volume ratio of 1:3 at room temperature for 30 min, followed by a fifth centrifugation. The solid obtained from the fifth centrifugation, after drying, became the medium molecular weight organic photovoltaic polymer donor material. The solid c obtained from the fourth centrifugation, after drying, became the high molecular weight organic photovoltaic polymer donor material. Solvent A1 was methanol, solvent A2 consisted of ethanol and tert-butanol in a volume ratio of 3:1, solvent A3 consisted of ethanol and 2-methyl-2-butanol in a volume ratio of 3:2, solvent B consisted of n-hexane and isooctane in a volume ratio of 6:2, solvent C consisted of acetone and methyl tert-butyl ketone in a volume ratio of 5:3, and solvent D was xylene.

[0032] Example 2

[0033] The preparation process of the organic photovoltaic polymer donor material in this embodiment includes the following steps:

[0034] (1) 2,5-Dibromothiophene-3,4-dicarboxylic acid and thionyl chloride in a molar ratio of 1:14 were added to a reaction vessel, heated to 82°C, stirred and refluxed for 7 h, and then distilled under reduced pressure to remove unreacted thionyl chloride, yielding 2,5-dibromothiophene-3,4-diacyl chloride; then 2,5-dibromothiophene-3,4-diacyl chloride and anhydrous tetrahydrofuran in a mass ratio of 1:2 were added to the reaction vessel, stirred evenly, and then 4-isopropylcyclohexanol (the molar ratio of 4-isopropylcyclohexanol and 2,5-dibromothiophene-3,4-diacyl chloride was 7:1) was added, heated to 78°C, stirred and refluxed for 13 h, and then distilled under reduced pressure to remove the solvent, yielding a crude product. The crude product was purified by column chromatography using ethyl acetate, petroleum ether and dichloromethane in a volume ratio of 3:1:1 to obtain a dibromothiophene alcohol ester compound (pale yellow solid). The chemical structure of the dibromothiophene alcohol ester compound is as follows: .

[0035] (2) A dibromothiophene ester compound, 2-(tributyltinyl)thiophene, tetra(triphenylphosphine)palladium, and anhydrous toluene in a molar ratio of 1:3.2:0.2:185 were added to a reaction vessel. Argon gas was then introduced, and the mixture was stirred until homogeneous. The mixture was then heated to 108°C and stirred for 22 hours. The solvent was removed by vacuum distillation to obtain a crude product. The crude product was purified by column chromatography using ethyl acetate, petroleum ether, and dichloromethane in a volume ratio of 4:1:1 to obtain a bithiophene ester compound (yellow solid). The chemical structure of the bithiophene ester compound is as follows: .

[0036] (3) Add the bithiophene ester compound and anhydrous tetrahydrofuran in a mass ratio of 1:55 to the reaction vessel and stir until the bithiophene ester compound is fully dissolved. Then, add a 60% (w / w) tetrahydrofuran solution of N-bromosuccinimide to the reaction vessel and stir at room temperature for 22 h. After the reaction is completed, add water and dichloromethane to the reaction vessel, stir evenly, and let stand to separate the layers. Separate the organic phase and distill under reduced pressure to obtain the crude product. Purify the crude product by column chromatography using ethyl acetate, petroleum ether and dichloromethane in a volume ratio of 4:1:1 to obtain the dibromobithiophene ester compound (yellow solid). The molar ratio of the bithiophene ester compound to N-bromosuccinimide is 1:2.3. The chemical structure of the dibromobithiophene ester compound is as follows: .

[0037] (4) A dibromobisthiophene ester compound, an organotin compound, tetrakis(triphenylphosphine)palladium, and toluene in a molar ratio of 1:1:0.12:32 were added to a reaction vessel. Argon gas was then introduced into the reaction vessel, and after stirring until homogeneous, the mixture was heated to 118°C and stirred for 33 hours. The mixture was then cooled to room temperature to obtain an organic photovoltaic polymer donor material solution. The chemical structure of the organotin compound is as follows: .

[0038] (5) Add the organic photovoltaic polymer donor material solution and solvent A1 to the stirred tank at a volume ratio of 1:2. After stirring at room temperature for 60 min, perform the first centrifugation. The solid a obtained from the first centrifugation is the crude organic photovoltaic polymer donor material, and the liquid a obtained from the first centrifugation is the waste liquid. Then add the solid a and solvent B to the stirred tank at a mass ratio of 1:25. Heat to 38°C and ultrasonically disperse for 80 min, then perform the second centrifugation. Mix the liquid b obtained from the second centrifugation and solvent A2 at a volume ratio of 1:7 at 55°C for 40 min, then perform the third centrifugation. The solid obtained from the third centrifugation is the low molecular weight organic photovoltaic polymer donor material after drying.

[0039] The solid b obtained from the second centrifugation and a mixed solvent consisting of solvents C and D in a volume ratio of 1:2 were added to a stirred tank in a mass ratio of 1:12. After heating to 52°C and stirring for 130 min, a fourth centrifugation was performed. The liquid c obtained from the fourth centrifugation and solvent A3 were mixed in a volume ratio of 1:4 at room temperature for 40 min, followed by a fifth centrifugation. The solid obtained from the fifth centrifugation, after drying, became the medium molecular weight organic photovoltaic polymer donor material. The solid c obtained from the fourth centrifugation, after drying, became the high molecular weight organic photovoltaic polymer donor material. Solvent A1 was methanol, solvent A2 consisted of ethanol and tert-butanol in a volume ratio of 4:1, solvent A3 consisted of ethanol and 2-methyl-2-butanol in a volume ratio of 4:3, solvent B consisted of n-hexane and isooctane in a volume ratio of 6:3, solvent C consisted of acetone and methyl tert-butyl ketone in a volume ratio of 7:3, and solvent D was xylene.

[0040] Example 3

[0041] The preparation process of the organic photovoltaic polymer donor material in this embodiment includes the following steps:

[0042] (1) 2,5-Dibromothiophene-3,4-dicarboxylic acid and thionyl chloride in a molar ratio of 1:15 were added to a reaction vessel, heated to 85°C, stirred and refluxed for 8 h, and then distilled under reduced pressure to remove unreacted thionyl chloride, yielding 2,5-dibromothiophene-3,4-diacyl chloride; then 2,5-dibromothiophene-3,4-diacyl chloride and anhydrous tetrahydrofuran in a mass ratio of 1:3 were added to a reaction vessel, stirred evenly, and then 4-isopropylcyclohexanol (the molar ratio of 4-isopropylcyclohexanol and 2,5-dibromothiophene-3,4-diacyl chloride was 8:1) was added, heated to 80°C, stirred and refluxed for 15 h, and then distilled under reduced pressure to remove the solvent, yielding a crude product. The crude product was purified by column chromatography using ethyl acetate, petroleum ether and dichloromethane in a volume ratio of 3:1:1 to obtain a dibromothiophene alcohol ester compound (pale yellow solid). The chemical structure of the dibromothiophene alcohol ester compound is as follows: .

[0043] (2) A dibromothiophene ester compound, 2-(tributyltinyl)thiophene, tetra(triphenylphosphine)palladium and anhydrous toluene in a molar ratio of 1:3.5:0.2:190 were added to a reaction vessel, and argon gas was introduced. After stirring evenly, the mixture was heated to 110°C and stirred for 24 hours. The solvent was removed by vacuum distillation to obtain a crude product. The crude product was purified by column chromatography using ethyl acetate, petroleum ether and dichloromethane in a volume ratio of 4:1:1 to obtain a bithiophene ester compound (yellow solid). The chemical structure of the bithiophene ester compound is as follows: .

[0044] (3) The bithiophene ester compound and anhydrous tetrahydrofuran in a mass ratio of 1:60 were added to the reaction vessel and stirred until the bithiophene ester compound was fully dissolved. Then, a 60% (w / w) tetrahydrofuran solution of N-bromosuccinimide was added dropwise to the reaction vessel. The reaction was stirred at room temperature for 24 h. After the reaction was completed, water and dichloromethane were added to the reaction vessel. After stirring evenly, the mixture was allowed to stand and separate into layers. The organic phase was separated and then distilled under reduced pressure to obtain the crude product. The crude product was purified by column chromatography using ethyl acetate, petroleum ether and dichloromethane in a volume ratio of 4:1:1 to obtain the dibromobithiophene ester compound (yellow solid). The molar ratio of the bithiophene ester compound to N-bromosuccinimide was 1:2.4. The chemical structure of the dibromobithiophene ester compound is as follows: .

[0045] (4) A dibromobisthiophene ester compound, an organotin compound, tetrakis(triphenylphosphine)palladium, and toluene in a molar ratio of 1:1:0.15:35 were added to a reaction vessel. Argon gas was then introduced into the reaction vessel, and after stirring until homogeneous, the mixture was heated to 120°C and stirred for 35 hours. The mixture was then cooled to room temperature to obtain an organic photovoltaic polymer donor material solution. The chemical structure of the organotin compound is as follows: .

[0046] (5) Add the organic photovoltaic polymer donor material solution and solvent A1 to the stirred tank at a volume ratio of 1:3. After stirring at room temperature for 100 min, perform the first centrifugation. The solid a obtained from the first centrifugation is the crude organic photovoltaic polymer donor material, and the liquid a obtained from the first centrifugation is the waste liquid. Then add the solid a and solvent B to the stirred tank at a mass ratio of 1:30. Heat to 40°C, ultrasonically disperse for 100 min, and perform the second centrifugation. Mix the liquid b obtained from the second centrifugation and solvent A2 at a volume ratio of 1:8 at 60°C for 60 min, and perform the third centrifugation. The solid obtained from the third centrifugation is the low molecular weight organic photovoltaic polymer donor material after drying.

[0047] The solid b obtained from the second centrifugation and a mixed solvent consisting of solvents C and D in a volume ratio of 1:3 were added to a stirred tank at a mass ratio of 1:15. After heating to 55°C and stirring for 90-180 min, a fourth centrifugation was performed. The liquid c obtained from the fourth centrifugation and solvent A3 were mixed at a volume ratio of 1:5 at room temperature for 60 min, followed by a fifth centrifugation. The solid obtained from the fifth centrifugation, after drying, became the medium molecular weight organic photovoltaic polymer donor material. The solid c obtained from the fourth centrifugation, after drying, became the high molecular weight organic photovoltaic polymer donor material. Solvent A1 was methanol; solvent A2 consisted of ethanol and tert-butanol in a volume ratio of 5:2; solvent A3 consisted of ethanol and 2-methyl-2-butanol in a volume ratio of 5:3; solvent B consisted of n-hexane and isooctane in a volume ratio of 7:3; solvent C consisted of acetone and methyl tert-butyl ketone in a volume ratio of 8:4; and solvent D was xylene.

[0048] Example 4

[0049] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that in step (1) of the preparation process of the organic photovoltaic polymer donor material in this comparative example, 4-isopropylcyclohexanol is replaced with decacarbonol.

[0050] Example 5

[0051] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that 4-isopropylcyclohexanol is replaced with cyclohexanol in step (1) of the preparation process of the organic photovoltaic polymer donor material in this comparative example.

[0052] Example 6

[0053] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is only that the chemical structure of the organotin compound in step (4) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is as follows: .

[0054] Comparative Example 1

[0055] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent A2 in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is ethanol.

[0056] Comparative Example 2

[0057] The only difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent A2 in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is tert-butanol.

[0058] Comparative Example 3

[0059] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent A2 in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is composed of ethanol and 2-methyl-2-butanol in a volume ratio of 3:1.

[0060] Comparative Example 4

[0061] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent A2 in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is composed of ethanol and isopropanol in a volume ratio of 3:1.

[0062] Comparative Example 5

[0063] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the temperature of stirring and mixing the liquid b obtained from the second centrifugation and solvent A2 in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is adjusted from 50°C to 45°C.

[0064] Comparative Example 6

[0065] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the temperature of stirring and mixing the liquid b obtained from the second centrifugation and solvent A2 in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is adjusted from 50°C to 65°C.

[0066] Comparative Example 7

[0067] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent A3 in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is ethanol.

[0068] Comparative Example 8

[0069] The only difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent A3 in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is 2-methyl-2-butanol.

[0070] Comparative Example 9

[0071] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent A3 in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is composed of ethanol and tert-butanol in a volume ratio of 3:2.

[0072] Comparative Example 10

[0073] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent A3 in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is composed of ethanol and n-pentanol in a volume ratio of 3:2.

[0074] Comparative Example 11

[0075] The only difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example, solvent A3 is composed of ethanol and 3-methylbutanol in a volume ratio of 3:2.

[0076] Comparative Example 12

[0077] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent A3 in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is composed of ethanol and 2-methyl-2-pentanol in a volume ratio of 3:2.

[0078] Comparative Example 13

[0079] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent B in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is composed of n-hexane and n-octane in a volume ratio of 6:2.

[0080] Comparative Example 14

[0081] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent B in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is composed of n-hexane and isoheptane in a volume ratio of 6:2.

[0082] Comparative Example 15

[0083] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent B in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is composed of n-hexane and isodecane in a volume ratio of 6:2.

[0084] Comparative Example 16

[0085] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent B in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is n-hexane.

[0086] Comparative Example 17

[0087] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the solvent B in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is isooctane.

[0088] Comparative Example 18

[0089] The only difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the ultrasonic dispersion temperature of solid a and solvent B in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is adjusted from 35°C to 30°C.

[0090] Comparative Example 19

[0091] The difference between the preparation process of the organic photovoltaic polymer donor material in this comparative example and the preparation process of the organic photovoltaic polymer donor material in Example 1 is that the temperature of ultrasonic dispersion of solid a and solvent B in step (5) of the preparation process of the organic photovoltaic polymer donor material in this comparative example is adjusted from 35°C to 45°C.

[0092] Experimental Example 1

[0093] To investigate the molecular weight, molecular weight distribution, and yield of the low-molecular-weight, medium-molecular-weight, and high-molecular-weight organic photovoltaic polymer donor materials prepared in each example and comparative example, GPC was used to test the number-average molecular weight and weight-average molecular weight of the materials. The ratio of weight-average molecular weight to number-average molecular weight was then calculated to obtain the dispersion index (PDI). The yield of the organic photovoltaic polymer donor materials with different molecular weights was obtained by calculating the ratio of the dry weight of the organic photovoltaic polymer donor material with different molecular weights to the dry weight of solid a (crude organic photovoltaic polymer donor material). The molecular weight, molecular weight distribution, and yield of the low-molecular-weight, medium-molecular-weight, and high-molecular-weight organic photovoltaic polymer donor materials prepared in each example and comparative example are shown in Table 1.

[0094] Table 1. Different molecular weights prepared in each example and comparative example.

[0095] Molecular weight, molecular weight distribution and yield of organic photovoltaic polymer donor materials

[0096]

[0097] Note: "-" indicates that it has not been tested.

[0098] As shown in Table 1, the preparation process of the organic photovoltaic polymer donor material of the present invention, through monomer synthesis, polymerization reaction, and post-reaction treatment, yielded three organic photovoltaic polymer donor materials with different molecular weights. The low molecular weight organic photovoltaic polymer donor material had a number average molecular weight of 10008~10021 and a dispersion coefficient (PDI) of 1.02~1.06; the medium molecular weight organic photovoltaic polymer donor material had a number average molecular weight of 13854~13917 and a PDI of 1.04~1.06; and the high molecular weight organic photovoltaic polymer donor material had a number average molecular weight of 17384~17462 and a PDI of 1.04~1.07. The total yield of the three organic photovoltaic polymer donor materials with different molecular weights was greater than 95%. Therefore, the preparation process of the organic photovoltaic polymer donor material of the present invention has good yield, and the prepared organic photovoltaic polymer donor material has a narrow molecular weight distribution, showing good application prospects.

[0099] As can be seen from Examples 1 and 4-6, when the polymer structure is adjusted by changing the monomer, the molecular weight distribution of the prepared polymers is relatively wide, indicating that the subsequent processing technology is not suitable for the polymers prepared after the structure is adjusted, and further screening of post-processing parameters is required.

[0100] As can be seen from Example 1 and Comparative Examples 1-6, solvent A2 has a significant impact on the yield of low molecular weight organic photovoltaic polymer donor materials. When a mixed solvent composed of ethanol and tert-butanol is used, the solvent has the best polarity compatibility with the low molecular weight organic photovoltaic polymer donor materials and the ability to recognize the low molecular weight organic photovoltaic polymer donor materials, which can ensure that the low molecular weight organic photovoltaic polymer donor materials are precipitated from liquid b most fully.

[0101] As can be seen from Example 1 and Comparative Examples 7-12, solvent A3 has a significant impact on the yield of medium molecular weight organic photovoltaic polymer donor materials. When a mixed solvent of ethanol and 2-methyl-2-butanol is used, the solvent has the best polarity compatibility with the medium molecular weight organic photovoltaic polymer donor materials and the ability to recognize the medium molecular weight organic photovoltaic polymer donor materials, which can ensure that the medium molecular weight organic photovoltaic polymer donor materials are precipitated from liquid c most fully.

[0102] As can be seen from Example 1 and Comparative Examples 13-19, solvent B has a significant impact on the separation effect of low molecular weight organic photovoltaic polymer donor materials, specifically in terms of the molecular weight distribution and yield of low molecular weight organic photovoltaic polymer donor materials. When a mixed solvent composed of hexane and isooctane is used, the polarity of the solvent can be optimally matched with the three organic photovoltaic polymer donor materials of different molecular weights, promoting the subsequent precipitation and separation of low molecular weight organic photovoltaic polymer donor materials as well as the dissolution and separation of medium and high molecular weight organic photovoltaic polymer donor materials.

[0103] In summary, this invention optimizes the post-processing of crude organic photovoltaic polymer donor materials to prepare three organic photovoltaic polymer donor materials with narrow molecular weight distributions. By selecting and compounding multiple solvents with branching and steric hindrance properties, the polarity, steric hindrance effect, and branching effect of the solvents are utilized to achieve efficient separation of the three organic photovoltaic polymer donor materials with different molecular weights.

[0104] Example of effect

[0105] To investigate the photovoltaic performance of the low-molecular-weight, medium-molecular-weight, and high-molecular-weight organic photovoltaic polymer donor materials prepared in each embodiment, organic photovoltaic polymer donor materials and PC71BM at a mass ratio of 1:1.2 were added to chlorobenzene and stirred to obtain a solution with a total concentration of 21 mg / mL of organic photovoltaic polymer donor materials and PC71BM, which was the photovoltaic active layer solution. The photovoltaic active layer solution was then spin-coated onto PEDOT:PSS-modified conductive glass to obtain a 120 nm thick photovoltaic active layer. A 5 mg / mL zinc oxide solution was then spin-coated onto the active layer to prepare a 10 nm thick cathode interface layer. Finally, a metal electrode was prepared using aluminum / lithium fluoride by vacuum evaporation to obtain a solar cell. The solar cell was then tested at AM 1.5G and an intensity of 100 mW / cm². 2 Under simulated sunlight conditions, solar cells were irradiated with nitrogen (water and oxygen content <0.1ppm), and the photoelectric conversion efficiency of the solar cells was tested and calculated. The results are shown in Table 2. The crude product in Table 2 represents the crude organic photovoltaic polymer donor material prepared in step (5) of each embodiment.

[0106] Table 2. Photovoltaic performance of organic photovoltaic polymer donor materials with different molecular weights prepared in Example 1.

[0107]

[0108] As shown in Table 2, the organic photovoltaic polymer donor materials prepared in this invention exhibit good photoelectric conversion efficiency. The photoelectric conversion efficiencies of low-molecular-weight, medium-molecular-weight, and high-molecular-weight organic photovoltaic polymer donor materials are all higher than those of unpurified organic photovoltaic polymer donor materials. Furthermore, the photoelectric conversion efficiency of high-molecular-weight organic photovoltaic polymer donor materials is higher than that of low-molecular-weight and medium-molecular-weight organic photovoltaic polymer donor materials. Compared to Examples 4-6, the photoelectric conversion efficiencies of the organic photovoltaic polymer donor materials with different molecular weights prepared in Examples 1-3 are higher. This is because the low-molecular-weight, medium-molecular-weight, and high-molecular-weight organic photovoltaic polymer donor materials prepared in Examples 1-3 have a narrower molecular weight distribution.

Claims

1. A preparation process for an organic photovoltaic polymer donor material, characterized in that, Includes the following steps: A dibromothiophene ester compound and an organotin compound were subjected to a Stille coupling reaction in toluene to obtain an organic photovoltaic polymer donor material solution. The organic photovoltaic polymer donor material solution was then mixed with solvent A1 and subjected to a first centrifugation. The solid a obtained from the first centrifugation was the crude organic photovoltaic polymer donor material. Solid a and solvent B were then heated and ultrasonically dispersed, followed by a second centrifugation. The liquid b obtained from the second centrifugation was heated and mixed with solvent A2, followed by a third centrifugation. The solid obtained from the third centrifugation, after drying, was the low molecular weight organic photovoltaic polymer donor material. Solid b obtained from the second centrifugation was heated and mixed with a mixed solvent, followed by a fourth centrifugation. The liquid c obtained from the fourth centrifugation was mixed with solvent A3, followed by a fifth centrifugation. The solid obtained from the fifth centrifugation, after drying, was the medium molecular weight organic photovoltaic polymer. Donor material; after drying the solid c obtained from the fourth centrifugation, a high molecular weight organic photovoltaic polymer donor material is obtained; solvent A1 is methanol, solvent A2 is composed of ethanol and tert-butanol in a volume ratio of 3~5:1~2, solvent A3 is composed of ethanol and 2-methyl-2-butanol in a volume ratio of 3~5:2~3; solvent B is composed of n-hexane and isooctane in a volume ratio of 6~7:2~3, the mixed solvent is composed of solvent C and solvent D in a volume ratio of 1:1~3, solvent C is composed of acetone and methyl tert-butyl ketone in a volume ratio of 5~8:3~4, and solvent D is xylene; solid a and solvent B are ultrasonically dispersed at a temperature of 35~40℃ for 60~100min, and liquid b obtained from the second centrifugation is mixed with solvent A2 at a temperature of 50~60℃ for 30~60min; the structure of the dibromobisthiophene ester compound is as follows: ; The structure of the organotin compound is as follows: .

2. The preparation process of the organic photovoltaic polymer donor material as described in claim 1, characterized in that, The volume ratio of the organic photovoltaic polymer donor material solution to solvent A1 is 1:1~3.

3. The preparation process of the organic photovoltaic polymer donor material as described in claim 1, characterized in that, The mass ratio of solid a to solvent B is 1:20~30.

4. The preparation process of the organic photovoltaic polymer donor material as described in claim 1, characterized in that, The volume ratio of liquid b to solvent A2 is 1:5~8.

5. The preparation process of the organic photovoltaic polymer donor material as described in claim 1, characterized in that, The solid b obtained from the second centrifugation and the mixed solvent were heated and mixed at a temperature of 50~55℃ for 90~180 min; the mass ratio of solid b to mixed solvent was 1:10~15.

6. The preparation process of the organic photovoltaic polymer donor material as described in claim 1, characterized in that, The volume ratio of liquid c to solvent A3 obtained from the fourth centrifugation is 1:3~5.

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