A preparation method based on thiadiazole quinoxaline-benzodithiophene photocatalyst

Abstract

The invention discloses a preparation method based on thiadiazole-quinoxaline-benzodithiophene photocatalyst, which belongs to the technical field of chemical organic synthesis. The method of the invention prepares near-infrared photoelectric materials based on the structural combination of thiadiazole-quinoxaline and benzodithiophene, which can improve the thermal stability of the material and its light absorption capacity in the near-infrared region. The thiadiazole-quinoxaline-benzodithiophene near-infrared photoelectric catalytic material prepared by the present invention has a near-infrared light absorption capacity so that it can effectively utilize natural light to drive chemical reactions during photocatalysis and photothermal catalysis, reduce traditional energy consumption and reduce carbon emissions; at the same time, it can be used as a photoelectric catalytic electrode material to generate electric charges by absorbing near-infrared light, promote the electrochemical conversion of CO, and improve energy conversion efficiency.

Description

Technical Field

[0001] The invention belongs to the field of chemical organic synthesis, and in particular is a method for preparing a thiadiazole-quinoxaline-benzodithiophene near-infrared photoelectric catalytic material. Background Art

[0002] In the field of research and application of modern energy technology, especially in chemical enterprises using coal as raw materials, the key to technological innovation is to effectively convert carbon monoxide into valuable chemicals, such as acetic acid. Organic photocatalysts have demonstrated their unique advantages and potential in this process. These materials can activate carbon monoxide by using sunlight and promote its chemical transformation with other reactants.

[0003] Among these materials, the combination of thiadiazoquinoxaline (TQ) and benzodithiophene (BDT) is particularly important. As an electron-accepting unit, TQ can extend the activation wavelength of photocatalysis to the near-infrared region through its narrow band gap characteristics. At the same time, as an electron-donating unit, BDT enhances the light absorption and electron transport capabilities of the entire polymer through its excellent structural modifiability and conjugation. With the continuous advancement of photocatalytic technology and in-depth research, this new photocatalytic system is expected to play a greater role in coal chemical industry and other energy conversion fields, providing strong technical support for the realization of more efficient and environmentally friendly chemical production.

[0004] Therefore, it is very necessary to optimize the efficiency of photocatalytic reactions and improve the stability and economy of photocatalytic systems by designing and applying structure-specific organic photocatalysts. This material can be used to achieve more efficient and environmentally friendly chemical production methods. For example, it can be used in coal chemical enterprises to catalyze the reaction of carbon monoxide with other reactants to produce acetic acid, which can not only improve the efficiency of the reaction, but also reduce energy consumption and operating costs. It provides an environmentally friendly and economical technical solution for chemical production, improves traditional chemical production processes, improves its environmental sustainability and economic benefits, and solves the problems of high energy consumption and serious environmental pollution in traditional chemical processes. Summary of the invention

[0005] Purpose of the invention: In order to improve the thermal stability of photocatalysts and their light absorption ability in the near-infrared region, the present invention provides a preparation method based on thiadiazole quinoxaline-benzodithiophene photocatalyst.

[0006] A preparation method based on thiadiazole quinoxaline-benzodithiophene photocatalyst comprises the following steps:

[0007] Step 1, preparation of 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene:

[0008] Step 1.1, adding bithiophene into a flask filled with argon, then adding anhydrous THF, and cooling the mixed solution;

[0009] Step 1.2, adding n-butyl lithium solution dropwise, and then waiting for the mixture to slowly heat up to a certain temperature and react for a period of time;

[0010] Step 1.3, then add 9-(bromomethyl)nonadecane all at once, heat the mixed solution to a certain temperature and reflux to react overnight; after the reaction is completed, pour the mixture into ice water to quench, then extract with petroleum ether, and the extracted organic phase is dried over anhydrous magnesium sulfate, filtered, and then the solvent (petroleum ether) is removed under reduced pressure and purified by column chromatography to obtain a colorless oily product.

[0011] Step 2, preparation of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione:

[0012] Step 2.1, add aluminum chloride into a flask, evacuate and pass argon gas, then add anhydrous 1,2-dichloroethane, and cool the mixed solution;

[0013] Step 2.2, then use a syringe to add 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene, pyridine and oxalyl chloride obtained in step 1 in sequence;

[0014] Step 2.3, then the mixture is slowly heated to room temperature and stirred to react; after the reaction is completed, the mixture is poured into ice water and extracted with dichloromethane; the organic phase is dried over anhydrous magnesium sulfate, the anhydrous magnesium sulfate is removed by filtration and the solvent (dichloromethane) is removed under reduced pressure, and the residue is purified by column chromatography to obtain a purple viscous oily product.

[0015] Step 3, Preparation of 4,7-dibromobenzo[c][1,2,5]thiadiazole-5,6-diamine:

[0016] 4,7-Dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole and iron powder are added to a flask, and then acetic acid is added. After argon gas is blown for a period of time, the mixture is heated and stirred for reaction. After the reaction is completed, the reaction mixture is poured into water, and then filtered and the filter cake is washed with anhydrous THF. The solvent (THF) is removed under reduced pressure, and then dried in vacuum at room temperature to obtain a yellow powder.

[0017] Step 4, Preparation of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine:

[0018] A suspension of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione prepared in step 2 and 4,7-dibromobenzo[c][1,2,5]thiadiazole-5,6-diamine prepared in step 3 is added to acetic acid, and after argon gas is blown for a period of time, the mixture is heated and stirred to react overnight; after the reaction is completed and cooled to room temperature, the product is filtered and washed with methanol, and then purified by column chromatography to obtain a dark green solid.

[0019] Step 5, Preparation of 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine:

[0020] 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine, trimethyl(thiophen-2-yl)stannane and catalyst Pd(pph) prepared in step 4 were added. 3 ) 4 Dissolve in a Schlenk tube filled with anhydrous toluene, evacuate and pass argon; stir the mixture at high temperature for a period of time; after the reaction is completed, pour the mixture into methanol and precipitate overnight, then collect the precipitate and purify it by column chromatography to obtain the product as a dark green solid.

[0021] Step 6, Preparation of 8,12-bis(5-bromothiophen-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine:

[0022] The 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine prepared in step 5 was dissolved in anhydrous THF at room temperature, N-bromosuccinimide (NBS) was added to the solution in the dark, and the mixture was stirred to react. After the reaction, THF was removed by rotary evaporation, and the monomer was purified by column chromatography to obtain a dark green solid.

[0023] Step 7, preparation of TQ-OD-BDT:

[0024] 8,12-bis(5-bromothien-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine, 2,6-bis(trimethyltin)-4,8-bis(5-(2-ethylhexyl)thienyl-2-)-benzodithiophene, and catalyst Pd prepared in step 6 were added. 2 (dba) 3 , ligand P(o-tol) 3 and anhydrous chlorobenzene are added to a Schlenk tube filled with argon, and then the mixture is heated and stirred for reaction. After the reaction is completed, the reaction mixture is precipitated into methanol at room temperature; the solid is collected by filtration and loaded into a Soxhlet extractor; it is washed with methanol, acetone, dichloromethane, chloroform, and chlorobenzene in sequence; the chlorobenzene solution is evaporated under reduced pressure, and methanol is added to precipitate the polymer; the polymer is collected and dried under vacuum to obtain a black flaky solid.

[0025] Preferably, in step 1:

[0026] (1) The dosage ratio of bithiophene, anhydrous THF, n-butyl lithium solution, and 9-(bromomethyl)nonadecane is (1.5-1.8) g: (30-50) mL: (15-20) mL: (5-10) g, and the concentration of n-butyl lithium solution is 2.5 M; in step 1.1, the cooling temperature is -78 °C;

[0027] (2) In step 1.2, the temperature is raised to 0°C and the reaction is carried out for 2 hours;

[0028] (3) In step 1.3, heat to 70°C and reflux overnight.

[0029] Preferably, in step 2:

[0030] (1) The dosage ratio of aluminum chloride, anhydrous 1,2-dichloroethane, 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene, pyridine and oxalyl chloride is (2.5 ~5) g: (50 ~80) mL: (2.5 ~5) g: (0.5 ~1.5) mL: (0.1 ~1) mL;

[0031] (2) In step 2.1, the cooling temperature is -42°C;

[0032] (3) In step 2.3, the stirring reaction time is 6 hours.

[0033] Preferably, in step 3:

[0034] (1) The dosage ratio of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole, iron powder and acetic acid is (0.1 ~0.3) g: (0.2 ~0.7) g: (10 ~30) mL;

[0035] (2) The argon gas is introduced for 15 minutes.

[0036] (3) The mixture was heated and stirred for reaction under the following conditions: heating temperature was 80°C and reaction time was 5 hours.

[0037] Preferably, in step 4:

[0038] (1) The dosage of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione, 4,7-dibromobenzo[c][1,2,5]thiadiazole-5,6-diamine and acetic acid is (100 ~200) mg: (30 ~80) mg: (10 ~20) mL;

[0039] (2) The time for introducing argon gas is 15 minutes;

[0040] (3) The mixture was heated and stirred for reaction under the following conditions: the temperature was heated to 100°C and the reaction was stirred overnight.

[0041] Preferably, in step 5:

[0042] (1), 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2',3'-c]phenazine, trimethyl(thiophen-2-yl)stannane, catalyst Pd(pph 3 ) 4 , the dosage ratio of anhydrous toluene and methanol is (100 ~500) mg: (100 ~300) mg: (10 ~30) mg: (1 ~10) mL: (100 ~500) mL;

[0043] (2) The conditions for heating and stirring the mixture to react are: the mixture is stirred at a high temperature of 100° C. for 24 hours.

[0044] Preferably, in step 6:

[0045] (1) The dosage ratio of 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2',3'-c]phenazine, THF and NBS is (100 ~500) mg: (10 ~30) ml: (50 ~200) mg;

[0046] (2) The stirring reaction conditions are: the stirring reaction time is 7 hours.

[0047] Preferably, in step 7:

[0048] (1) the 8,12-bis(5-bromothien-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithienyl[3,2-a:2′,3′-c]phenazine, 2,6-bis(trimethyltin)-4,8-bis(5-(2-ethylhexyl)thienyl-2-)-benzodithiophene, and catalyst Pd 2 (dba) 3 , ligand P( o -tol) 3 , the dosage ratio of anhydrous chlorobenzene is (100 ~400) mg: (100 ~400) mg: (5 ~20) mg: (10 ~50) mg: (5 ~10) mL;

[0049] (2) The conditions for heating and stirring the mixture to react are: heating the mixture to 120° C. and stirring the mixture for three days.

[0050] Beneficial effects: The thiazolylquinoxaline-benzodithiophene near-infrared photoelectric material synthesized by the method of the present invention has excellent near-infrared light absorption ability and outstanding thermal stability, and is an ideal photoelectric catalytic material, particularly suitable for use in the carbon monoxide (CO) conversion process. In coal chemical enterprises, the material can effectively promote the reaction between carbon monoxide and other reactants to produce high-value-added chemicals such as acetic acid. Its near-infrared light absorption performance enables efficient use of sunlight in the photocatalytic and photothermal catalytic processes, thereby improving reaction efficiency, reducing dependence on high temperature and high pressure conditions in traditional catalytic processes, and reducing energy consumption. At the same time, the good thermal stability of the material ensures that it maintains high efficiency in long-term operation on an industrial scale, reducing the frequency of material replacement and maintenance, thereby reducing operating costs. Based on these advantages, the material provides an environmentally friendly and economical technical solution for the production of chemicals in the coal chemical industry and other fields, which can significantly improve traditional production processes, improve the environmental sustainability and overall economic benefits of the process, and is expected to have a profound impact on the green development of the chemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is the hydrogen spectrum of 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene in Example 2.

[0052] Figure 2 This is the carbon spectrum of 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene in Example 2.

[0053] Figure 3 This is the hydrogen spectrum of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b′]dithiophene-4,5-dione in Example 2.

[0054] Figure 4 This is the carbon spectrum of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b′]dithiophene-4,5-dione in Example 2.

[0055] Figure 5 This is the hydrogen spectrum of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine in Example 2.

[0056] Figure 6 This is the carbon spectrum of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine in Example 2.

[0057] Figure 7 This is the hydrogen spectrum of 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine in Example 2.

[0058] Figure 8 This is the carbon spectrum of 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine in Example 2.

[0059] Fig. 9 This is the hydrogen spectrum of 8,12-bis(5-bromothiophen-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine in Example 2.

[0060] Fig.10 This is the carbon spectrum of 8,12-bis(5-bromothiophen-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine in Example 2.

[0061] Fig.11 This is the mass spectrum of 8,12-bis(5-bromothiophen-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine in Example 2.

[0062] Fig.12 This is the thermogravimetric analysis curve of TQ-OD-BDT in Example 2.

[0063] Fig.13The TQ-OD-BDT in Example 2 was dissolved in chlorobenzene (c=10 -5 M) and normalized UV-Vis-NIR absorption spectra in thin films.

[0064] Fig.14 This is the CV curve of TQ-OD-BDT in Example 2.

[0065] Fig.15 These are the atomic particle microscope height map and three-dimensional map of the TQ-OD-BDT film in Example 2. DETAILED DESCRIPTION

[0066] The technical solution of the present invention is described in detail below through specific embodiments, but the protection scope of the present invention is not limited to the embodiments.

[0067] Example 1: Step 1, Preparation of 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene:

[0068] 1.5 g of bithiophene was added to a flask filled with argon, and then 30 mL of anhydrous THF (tetrahydrofuran) was added. The mixed solution was cooled to -78 °C, and then 15 mL of 2.5 M n-butyl lithium solution was added dropwise, and then the mixture was slowly heated to 0 °C and reacted for 2 hours. Then 5 g of 9-(bromomethyl) nonadecane was added at one time, and the mixed solution was heated to 70 °C and refluxed overnight. After the reaction was completed, the mixture was poured into ice water to quench, and then extracted with petroleum ether. The organic phase obtained by extraction was dried with anhydrous magnesium sulfate, filtered, and the solvent was removed under reduced pressure and purified by column chromatography to obtain a colorless oily product.

[0069] Step 2, preparation of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione:

[0070] 2.5 g of aluminum chloride was added to the flask, and argon was passed through the flask under vacuum. Then 50 mL of anhydrous 1,2-dichloroethane was added, and the mixed solution was cooled to -42 ° C. Then 2.5 g of the product obtained in step 1, 0.5 mL of pyridine and 0.1 mL of oxalyl chloride were added in sequence using a syringe. After that, the mixture was slowly warmed to room temperature and stirred for 6 hours. After the reaction was completed, the mixture was poured into ice water, extracted with dichloromethane, and the organic phase was dried over anhydrous magnesium sulfate. The anhydrous magnesium sulfate was removed by filtration and the solvent was removed under reduced pressure. The residue was purified by column chromatography to obtain a purple viscous oily product.

[0071] Step 3, Preparation of 4,7-dibromobenzo[c][1,2,5]thiadiazole-5,6-diamine:

[0072] 0.1 g of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole and 0.2 g of iron powder were added to a flask, followed by 10 mL of acetic acid, argon was blown for 15 minutes, the mixture was heated to 80°C and stirred for 5 hours. After the reaction was completed, the reaction mixture was poured into water, then filtered and the filter cake was washed with THF, the solvent was removed under reduced pressure, and then vacuum dried at room temperature to obtain a yellow powder.

[0073] Step 4, Preparation of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine:

[0074] A suspension of 100 mg of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione prepared in step 2 and 30 mg of 4,7-dibromobenzo[c][1,2,5]thiadiazole-5,6-diamine prepared in step 3 was added to 10 mL of acetic acid, and then purged with argon for 15 minutes, and the mixture was heated to 100°C and stirred to react overnight. After the reaction was completed and cooled to room temperature, the product was filtered and washed with methanol, and then purified by column chromatography to obtain a dark green solid.

[0075] Step 5, Preparation of 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine:

[0076] 100 mg of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine prepared in step 4, 100 mg of trimethyl(thiophen-2-yl)stannane and 10 mg of catalyst Pd(pph) were added. 3 ) 4 Dissolve in a Schlenk tube filled with 1 mL of anhydrous toluene, evacuate and pass argon. Stir the mixture at 100°C for 24 hours. After the reaction, pour the mixture into 100 mL of methanol for precipitation overnight, then collect the precipitate and purify by column chromatography to obtain the product as a dark green solid.

[0077] Step 6. Preparation of 8,12-bis(5-bromothiophen-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazolo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine: 100 mg of 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine prepared in step 5 was dissolved in 10 mL of THF at room temperature. 50 mg of N-bromosuccinimide (NBS) was added to the solution in the dark. The mixture was stirred and reacted for 7 hours. After the reaction, THF was removed by rotary evaporation and purified by column chromatography to obtain a dark green solid monomer.

[0078] Step 7, preparation of TQ-OD-BDT: 100 mg of 8,12-bis(5-bromothien-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine prepared in step 6, 100 mg of 2,6-bis(trimethyltin)-4,8-bis(5-(2-ethylhexyl)thienyl-2-)-benzodithiophene, and 5 mg of catalyst Pd 2 (dba) 3 、10mg ligand P(o-tol) 3 and 5 mL of anhydrous chlorobenzene were added to a Schlenk tube filled with argon, and the mixture was then heated to 120°C and stirred for three days. After the reaction was completed, the reaction mixture was precipitated into methanol at room temperature. The solid was collected by filtration and loaded into a Soxhlet extractor. It was washed with methanol, acetone, dichloromethane, chloroform, and chlorobenzene in sequence. The chlorobenzene solution was evaporated under reduced pressure, and methanol was added to precipitate the polymer. The polymer was collected and dried under vacuum to obtain a black flaky solid.

[0079] Example 2: Step 1, Preparation of 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene: 1.8 g bithiophene was added to a flask filled with argon, and then 50 mL of anhydrous THF was added, the mixed solution was cooled to -78°C, and then 20 mL of 2.5 M n-butyl lithium solution was added dropwise, and then the mixture was slowly heated to 0°C and reacted for 2 hours. Then 10 g of 9-(bromomethyl)nonadecane was added at one time, the mixed solution was heated to 70°C and refluxed overnight. After the reaction was completed, the mixture was poured into ice water to quench, and then extracted with petroleum ether. The organic phase obtained by extraction was dried with anhydrous magnesium sulfate, filtered, the solvent was removed under reduced pressure, and purified by column chromatography to obtain a colorless oily product.

[0080] Step 2, Preparation of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione: Add 5g of aluminum chloride to a flask, evacuate and pass argon, then add 80mL of anhydrous 1,2-dichloroethane, and cool the mixed solution to -42°C. Then, use a syringe to add 5g of the product obtained in step 1, 1.5mL of pyridine and 1mL of oxalyl chloride in sequence. After that, the mixture is slowly warmed to room temperature and stirred for 6 hours. After the reaction is completed, the mixture is poured into ice water, extracted with dichloromethane, and the organic phase is dried with anhydrous magnesium sulfate. The anhydrous magnesium sulfate is removed by filtration and the solvent is removed under reduced pressure. The residue is purified by column chromatography to obtain a purple viscous oily product.

[0081] Step 3, Preparation of 4,7-dibromobenzo[c][1,2,5]thiadiazole-5,6-diamine: 0.3 g of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole and 0.7 g of iron powder were added to a flask, and then 30 mL of acetic acid was added, argon was blown for 15 minutes, and the mixture was heated to 80° C. and stirred for 5 hours. After the reaction was completed, the reaction mixture was poured into water, and then filtered and the filter cake was washed with anhydrous THF, the solvent was removed under reduced pressure, and then vacuum dried at room temperature to obtain a yellow powder.

[0082] Step 4, Preparation of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine: A suspension of 200 mg of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione prepared in step 2 and 80 mg of 4,7-dibromobenzo[c][1,2,5]thiadiazo-5,6-diamine prepared in step 3 was added to 20 mL of acetic acid, and then purged with argon for 15 minutes, and the mixture was heated to 100°C and stirred to react overnight. After the reaction was completed and cooled to room temperature, the product was filtered and washed with methanol, and then purified by column chromatography to obtain a dark green solid.

[0083] Step 5. Preparation of 2,5-bis(2-octyldodecyl)-8,12-di(thien-2-yl)-[1,2,5]thiadiazolo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine: 500 mg of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazolo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine prepared in step 4, 300 mg of trimethyl(thien-2-yl)stannane and 30 mg of catalyst Pd(pph) were added. 3 ) 4Dissolve in a Schlenk tube filled with 10 mL of anhydrous toluene, evacuate and pass argon. Stir the mixture at 100°C for 24 hours. After the reaction, pour the mixture into 500 mL of methanol for precipitation overnight, then collect the precipitate and purify by column chromatography to obtain the product as a dark green solid.

[0084] Step 6. Preparation of 8,12-bis(5-bromothiophen-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazolo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine: 500 mg of 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine prepared in step 5 was dissolved in 30 mL of anhydrous THF at room temperature. 200 mg of N-bromosuccinimide (NBS) was added to the solution in the dark. The mixture was stirred and reacted for 7 hours. After the reaction, THF was removed by rotary evaporation and purified by column chromatography to obtain a dark green solid monomer.

[0085] Step 7, preparation of TQ-OD-BDT: 400 mg of 8,12-bis(5-bromothien-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine prepared in step 6, 400 mg of 2,6-bis(trimethyltin)-4,8-bis(5-(2-ethylhexyl)thienyl-2-)-benzodithiophene, and 20 mg of catalyst Pd 2 (dba) 3 、50mg ligand P(o-tol) 3 and 10 mL of anhydrous chlorobenzene were added to a Schlenk tube filled with argon, and the mixture was then heated to 120°C and stirred for three days. After the reaction was completed, the reaction mixture was precipitated into methanol at room temperature. The solid was collected by filtration and loaded into a Soxhlet extractor. It was washed with methanol, acetone, dichloromethane, chloroform, and chlorobenzene in sequence. The chlorobenzene solution was evaporated under reduced pressure, and methanol was added to precipitate the polymer. The polymer was collected and dried under vacuum to obtain a black flaky solid.

[0086] Example 3: Step 1, Preparation of 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene: 1.67 g bithiophene was added to a flask filled with argon, and then 40 mL of anhydrous THF was added, the mixed solution was cooled to -78°C, and then 18.4 mL of 2.5 M n-butyl lithium solution was added dropwise, and then the mixture was slowly heated to 0°C and reacted for 2 hours. Then 7.92 g of 9-(bromomethyl)nonadecane was added at one time, the mixed solution was heated to 70°C and refluxed overnight. After the reaction was completed, the mixture was poured into ice water to quench, and then extracted with petroleum ether. The organic phase obtained by extraction was dried with anhydrous magnesium sulfate, filtered, the solvent was removed under reduced pressure, and purified by column chromatography to obtain a colorless oily product.

[0087] Step 2, Preparation of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione: Add 3.35 g of aluminum chloride to a flask, evacuate and pass argon, then add 70 mL of anhydrous 1,2-dichloroethane, and cool the mixed solution to -42°C. Then, use a syringe to add 3.63 g of the product obtained in step 1, 1 mL of pyridine and 0.45 mL of oxalyl chloride in sequence. After that, the mixture is slowly warmed to room temperature and stirred for 6 hours. After the reaction is completed, the mixture is poured into ice water, extracted with dichloromethane, and the organic phase is dried over anhydrous magnesium sulfate. The anhydrous magnesium sulfate is removed by filtration and the solvent is removed under reduced pressure. The residue is purified by column chromatography to obtain a purple viscous oily product.

[0088] Step 3, Preparation of 4,7-dibromobenzo[c][1,2,5]thiadiazole-5,6-diamine: 0.23 g of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole and 0.4 g of iron powder were added to a flask, and then 15 mL of acetic acid was added, argon was blown for 15 minutes, and the mixture was heated to 80° C. and stirred for 5 hours. After the reaction was completed, the reaction mixture was poured into water, and then filtered and the filter cake was washed with anhydrous THF, the solvent was removed under reduced pressure, and then vacuum dried at room temperature to obtain a yellow powder.

[0089] Step 4, Preparation of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine: A suspension of 156.2 mg of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b′]dithiophene-4,5-dione prepared in step 2 and 64.8 mg of 4,7-dibromobenzo[c][1,2,5]thiadiazo-5,6-diamine prepared in step 3 was added to 15 mL of acetic acid, and then purged with argon for 15 minutes, and the mixture was heated to 100°C and stirred to react overnight. After the reaction was completed and cooled to room temperature, the product was filtered and washed with methanol, and then purified by column chromatography to obtain a dark green solid.

[0090] Step 5, Preparation of 2,5-bis(2-octyldodecyl)-8,12-di(thien-2-yl)-[1,2,5]thiadiazolo[3,4-i]dithien-[3,2-a:2′,3′-c]phenazine: 320 mg of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazolo[3,4-i]dithien-[3,2-a:2′,3′-c]phenazine prepared in step 4, 185 mg of trimethyl(thien-2-yl)stannane and 20 mg of catalyst Pd(pph) were added. 3 ) 4 Dissolve in a Schlenk tube filled with 5 mL of anhydrous toluene, evacuate and pass argon. Stir the mixture at 100°C for 24 hours. After the reaction, pour the mixture into 300 mL of methanol for precipitation overnight, then collect the precipitate and purify by column chromatography to obtain the product as a dark green solid.

[0091] Step 6. Preparation of 8,12-bis(5-bromothiophen-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazolo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine: 322.38 mg of 2,5-bis(2-octyldodecyl)-8,12-bis(thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine prepared in step 5 was dissolved in 15 mL of anhydrous THF at room temperature. 117.48 mg of N-bromosuccinimide (NBS) was added to the solution in the dark. The mixture was stirred and reacted for 7 hours. After the reaction, THF was removed by rotary evaporation and purified by column chromatography to obtain a dark green solid monomer.

[0092] Step 7, preparation of TQ-OD-BDT: 246.48 mg of 8,12-bis(5-bromothien-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine prepared in step 6, 180.91 mg of 2,6-bis(trimethyltin)-4,8-bis(5-(2-ethylhexyl)thienyl-2-)-benzodithiophene, and 11 mg of catalyst Pd 2 (dba) 3 、30.6mg ligand P(o-tol) 3 and 7 mL of anhydrous chlorobenzene were added to a Schlenk tube filled with argon, and the mixture was then heated to 120 ° C and stirred for three days. After the reaction was completed, the reaction mixture was precipitated into methanol at room temperature. The solid was collected by filtration and loaded into a Soxhlet extractor. It was washed with methanol, acetone, dichloromethane, chloroform, and chlorobenzene in sequence. The chlorobenzene solution was evaporated under reduced pressure, and methanol was added to precipitate the polymer. The polymer was collected and dried under vacuum to obtain a black flaky solid.

[0093] Figures 1 to 14 The test results of the product prepared in Example 2 are as follows. Specifically:

[0094] Figure 1 As shown, the hydrogen spectrum of 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene, the nuclear magnetic resonance hydrogen spectrum data are as follows: 1 HNMR (400 MHz, Chloroform-d) δ 6.90 (d, J = 3.5 Hz, 2H), 6.61 (d, J = 3.5 Hz, 2H), 2.70 (d, J = 6.6 Hz, 4H), 1.61 (t, J = 5.8 Hz, 2H), 1.26 (d, J = 3.2 Hz, 64H), 0.90 – 0.87 (m, 12H).

[0095] Figure 2 As shown, the carbon spectrum of 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene, the NMR carbon spectrum data are as follows: 13C NMR (101 MHz, Chloroform-d) δ 142.87, 135.67, 125.59, 122.28, 39.98,39.54, 39.25, 34.55, 33.21, 32.64, 32.01, 31.99, 30.04, 29.89, 29.77, 29.75,29.73, 29.69, 29.65, 29.45, 29.40, 26.67, 26.64, 22.77, 22.75, 14.14.

[0096] Figure 3 As shown, the hydrogen spectrum of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione, the nuclear magnetic resonance hydrogen spectrum data are as follows: 1 H NMR (400 MHz, Chloroform-d) δ 7.10 (s, 2H), 2.69 (d, J = 6.6 Hz, 4H), 1.62 (s, 2H), 1.27 (d, J = 8.5 Hz, 64H), 0.87 (t, J = 6.7 Hz, 12H).

[0097] Figure 4 As shown, the carbon spectrum of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione, the NMR carbon spectrum data are as follows: 13 C NMR (101 MHz, Chloroform- d ) δ 174.55, 145.25, 142.72,134.56, 125.07, 39.79, 34.29, 33.07, 31.93, 31.90, 31.42, 30.17, 29.88,29.72, 29.65, 29.58, 29.36, 29.32, 26.56, 22.69, 14.11.

[0098] Figure 5 As shown, the hydrogen spectrum of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine, the H NMR spectrum data are as follows: 1 H NMR (400 MHz, Chloroform- d ) δ8.03 (s, 2H), 2.96 (d, J= 6.8 Hz, 4H), 1.79 (m, 2H), 1.32-1.22 (m, 64H), 0.85 (dt, J = 6.9, 3.7 Hz, 12H).

[0099] Figure 6 As shown, the carbon spectrum of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine, the NMR carbon spectrum data are as follows: 13 C NMR (101 MHz, Chloroform-d) δ151.44, 144.87, 142.18, 137.71, 137.41, 133.10, 123.34, 113.23, 40.19, 35.16,33.28, 31.93, 30.00, 29.71, 29.68, 29.37, 26.68, 22.69, 14.13.

[0100] Figure 7 As shown, the hydrogen spectrum of 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine, the H NMR spectrum data are as follows: 1 H NMR (400 MHz, Chloroform-d) δ 9.05 (d, J = 3.9 Hz, 2H), 7.91 (s, 2H), 7.58 (d, J = 5.1 Hz, 2H), 7.23 – 7.19 (m, 2H), 2.92 (d, J = 6.6 Hz, 4H), 1.78 (s, 2H), 1.46 – 1.20 (m, 64H), 0.85 (td, J = 6.9, 2.5 Hz, 12H).

[0101] Figure 8 As shown, the carbon spectrum of 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine, the NMR carbon spectrum data are as follows: 13C NMR (101 MHz, Chloroform-d) δ 149.44, 143.73, 138.28, 137.38, 136.30, 133.19, 133.00,132.74, 128.71, 124.45, 120.51, 118.38, 39.94, 34.97, 33.37, 31.99, 31.95,30.12, 29.81, 29.78, 29.74, 29.46, 29.41, 26.80, 22.72, 22.69, 14.13, 14.11.

[0102] Fig. 9 As shown, the hydrogen spectrum of 8,12-bis(5-bromothien-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine, the H NMR spectrum data are as follows: 1 H NMR (400 MHz, Chloroform-d) δ 8.68 (d, J = 4.3 Hz, 2H), 7.59 (s, 2H), 6.98 (d, J = 4.3 Hz, 2H), 2.88 (d, J = 6.5 Hz, 4H), 1.78 (s, 2H), 1.48 – 1.17 (m, 64H), 0.84 (td,J = 6.7, 4.2 Hz, 12H).

[0103] Fig.10 As shown, the carbon spectrum of 8,12-bis(5-bromothien-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine, the NMR carbon spectrum data are as follows: 13 C NMR (101 MHz, Chloroform-d) δ 149.44, 143.73, 138.28, 137.38, 136.30, 133.19, 133.00,132.74, 128.71, 124.45, 120.51, 118.38, 39.94, 34.97, 33.37, 31.99, 31.95,30.12, 29.81, 29.78, 29.74, 29.46, 29.41, 26.80, 22.72, 22.69, 14.13, 14.11.

[0104] Fig.11Shown is the mass spectrum of 8,12-bis(5-bromothien-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine.

[0105] Fig.12 As shown in the thermogravimetric analysis curve of TQ-OD-BDT, the temperature corresponding to 5% heat loss is defined as the thermal decomposition temperature. The thermal decomposition temperature of TQ-OD-BDT is 383.3 ℃, which has good thermal stability.

[0106] Fig.13 As shown, TQ-OD-BDT in chlorobenzene (c=10 -5 The absorption spectra of polymers in solution and film can be divided into two sections. The first section is 300-700 nm, which is the π-π * The second absorption band is 800-1800 nm, which represents the ICT between the polymer electron donor and the electron acceptor. The maximum absorption peak of TQ-OD-BDT in solution is 1058 nm, and a 42 nm red shift occurs in the film. The absorption intensity is also improved, indicating that the film has a stronger aggregation strength. edge is 1473 nm, substitute into the formula Eg=1240 / λ edge The optical band gap of TQ-OD-BDT calculated in the paper is 0.84 eV, which is a narrow band gap photocatalytic material. The influence of the band gap is mainly reflected in the absorption spectrum. From the calculation formula of the band gap, it can be concluded that the narrower the band gap, the larger the range of light absorption.

[0107] Fig.14 As shown in the CV curve of TQ-OD-BDT, the electrochemical HOMO and LUMO energy levels of the polymer can be calculated through the starting potentials of oxidation (right) and reduction (left). The figure shows that the starting potentials of oxidation and reduction are 0.83 V and -0.24 V, respectively, the HOMO and LUMO energy levels are -5.23 eV and -4.16 eV, respectively, and the electrochemical band gap is 1.07 eV.

[0108] Fig.15 As shown in the figure, the surface morphology of the polymer TQ-OD-BDT film was characterized by atomic force microscopy (AFM), where (A) is the AFM height map. According to the morphological results, the root mean square (RMS) of the roughness of TQ-OD-T is 800.01 pm, and (B) is the AFM height map in 3D mode. The larger the RMS value, the worse the surface morphology of the film, which is not conducive to exciton diffusion and charge separation.

[0109] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and details may be made without departing from the spirit and scope of the present invention.

Claims

1. A method for preparing a thiadiazole-quinoxaline-benzodithiophene photocatalyst, characterized in that: The steps include: Step 1, preparation of 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene: Step 1.1, add bithiophene into a flask filled with argon, add anhydrous THF, and then cool the mixture to a temperature of -78°C; Step 1.2, add n-butyl lithium solution dropwise, slowly heat the mixture to 0°C, and react for 2 hours; Step 1.3, adding 9-(bromomethyl)nonadecane, and then heating the mixed solution to 70°C and refluxing the reaction overnight. After the reaction is completed, pouring into ice water to quench, extracting with petroleum ether, drying the organic phase obtained by extraction, filtering, removing solvent, and purifying to obtain a colorless oily product; Step 2, Preparation of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione: Step 2.1, add aluminum chloride into a flask, evacuate and pass argon, then add anhydrous 1,2-dichloroethane, and cool the mixed solution to a temperature of -42°C; Step 2.2, using a syringe to sequentially add 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene, pyridine and oxalyl chloride obtained in step 1; Step 2.3, then slowly warming to room temperature and stirring to react, after the reaction is completed, pouring the mixture into ice water, extracting with dichloromethane, drying the organic phase obtained by extraction, filtering, removing the solvent, and purifying to obtain a purple viscous oily product; Step 3, Preparation of 4,7-dibromobenzo[c][1,2,5]thiadiazole-5,6-diamine: 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole and iron powder are added to a flask, and then acetic acid is added. After argon gas is blown for a period of time, the mixture is heated and stirred for reaction. After the reaction is completed, the reaction mixture is poured into water, filtered, and the filter cake is washed with anhydrous THF to remove the solvent, and then dried in vacuum at room temperature to obtain a yellow powder. Step 4, Preparation of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine: Add a suspension of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione prepared in step 2 and 4,7-dibromobenzo[c][1,2,5]thiadiazole-5,6-diamine prepared in step 3 into acetic acid, introduce argon for a period of time, heat the mixture to 100°C and stir to react overnight; after the reaction is completed and cooled to room temperature, filter the product and wash with methanol, and purify to obtain a dark green solid; Step 5, Preparation of 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine: The 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine, trimethyl(thiophen-2-yl)stannane and catalyst Pd(pph3)4 prepared in step 4 were dissolved in a Schlenk tube filled with anhydrous toluene, and evacuated and argon was passed; the mixture was stirred at 100° C. for 24 hours; after the reaction, the mixture was poured into methanol for precipitation overnight, and the precipitate was collected and purified to obtain a dark green solid; Step 6, Preparation of 8,12-bis(5-bromothiophene-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine: The 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine prepared in step 5 was dissolved in anhydrous THF at room temperature, N-bromosuccinimide was added to the solution in the dark, and the mixture was stirred for reaction; after the reaction, THF was removed by rotary evaporation, and a dark green solid monomer was obtained after purification; Step 7, preparation of TQ-OD-BDT: The 8,12-bis(5-bromothiophene-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine prepared in step 6, 2,6-di(trimethyltin)-4,8-di(5-(2-ethylhexyl)thienyl-2-)-benzodithiophene, catalyst Pd2(dba)3, ligand P(o-tol)3 and anhydrous chlorobenzene are added to a Schlenk tube filled with argon, and then the mixture is heated to 120°C and stirred for three days; after the reaction is completed, the reaction mixture is precipitated into methanol at room temperature; the solid is collected by filtration and loaded into a Soxhlet extractor; washed with methanol, acetone, dichloromethane, chloroform and chlorobenzene in sequence; the chlorobenzene solution is evaporated under reduced pressure, and methanol is added to precipitate the polymer; the polymer is collected and dried under vacuum to obtain a black flaky solid.

2. The preparation method according to claim 1, characterized in that: In step 1: The usage ratio of bithiophene, anhydrous THF, n-butyl lithium solution and 9-(bromomethyl)nonadecane is (1.5-1.8) g:(30-50) mL:(15-20) mL:(5-10) g, and the concentration of n-butyl lithium solution is 2.5M.

3. The preparation method according to claim 1, characterized in that: In step 2: (1) The dosage ratio of aluminum chloride, anhydrous 1,2-dichloroethane, 5,5′-bis(2-octyldodecyl)-2,2′-bithiophene, pyridine and oxalyl chloride is (2.5-5) g: (50-80) mL: (2.5-5) g: (0.5-1.5) mL: (0.1-1) mL; (2) In step 2.3, the stirring reaction time is 6 hours.

4. The preparation method according to claim 1, characterized in that: In step 3: (1) The dosage ratio of 4,7-dibromo-5,6-dinitrobenzo[c][1,2,5]thiadiazole, iron powder and acetic acid is (0.1-0.3) g: (0.2-0.7) g: (10-30) mL; (2) The time for argon gas to be introduced is 15 minutes; (3) The mixture was heated and stirred for reaction under the following conditions: heating to 80°C and stirring for reaction for 5 hours.

5. The preparation method according to claim 1, characterized in that: In step 4: (1) The amount of 2,7-bis(2-octyldodecyl)benzo[2,1-b:3,4-b']dithiophene-4,5-dione, 4,7-dibromobenzo[c][1,2,5]thiadiazole-5,6-diamine and acetic acid is (100-200) mg: (30-80) mg: (10-20) mL; (2) The time for introducing argon gas is 15 minutes.

6. The preparation method according to claim 1, characterized in that: In step 5: The dosage ratio of 8,12-dibromo-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazolo[3,4-i]dithieno[3,2-a:2',3'-c]phenazine, trimethyl(thiophen-2-yl)stannane, catalyst Pd(pph3)4, anhydrous toluene and methanol is (100-500) mg: (100-300) mg: (10-30) mg: (1-10) mL: (100-500) mL.

7. The preparation method according to claim 1, characterized in that: In step 6: (1) The usage ratio of 2,5-bis(2-octyldodecyl)-8,12-di(thiophen-2-yl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2',3'-c]phenazine, THF and NBS is (100-500) mg: (10-30) ml: (50-200) mg; (2) The stirring reaction time is 7 hours.

8. The preparation method according to claim 1, characterized in that: In step 7: The dosage ratio of 8,12-bis(5-bromothiophen-2-yl)-2,5-bis(2-octyldodecyl)-[1,2,5]thiadiazo[3,4-i]dithieno[3,2-a:2′,3′-c]phenazine, 2,6-bis(trimethyltin)-4,8-di(5-(2-ethylhexyl)thienyl-2-)-benzodithiophene, catalyst Pd2(dba)3, ligand P(o-tol)3, and anhydrous chlorobenzene is (100~400) mg: (100~400) mg: (5~20) mg: (10~50) mg: (5~10) mL.

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