Selenophenol thiophene fused ring asymmetric acceptor material for organic solar cell as well as preparation method and application of selenophenol thiophene fused ring asymmetric acceptor material

Abstract

The invention discloses a selenophenol thiophene fused ring asymmetric acceptor material for an organic solar cell, the structural formula of the selenophenol thiophene fused ring asymmetric acceptor material is as shown in the formula 1: # imgabs0 #, and the BO side chain is # imgabs1 #. A non-fullerene acceptor material with good planarity, good film-forming property and low exciton binding energy is adopted; the material is characterized in that a selenophenol thiophene fused ring unit is introduced into a non-fullerene fused ring skeleton to asymmetrically synthesize the material, and the asymmetric unit is coupled to save the preparation process and time; according to the invention, a branched side chain, namely a 2-butyl octyl side chain substitution strategy is adopted in the selenophenol thiophene fused ring asymmetric acceptor material for the first time, a richer accumulation mode compared with a straight chain molecule is obtained, and charge transmission is promoted.

Description

Technical Field

[0001] The invention relates to a selenophene-thiophene fused ring asymmetric receptor material for organic solar cells, a preparation method and an application thereof, and in particular to a high-efficiency additive-free modified selenophene-thiophene fused ring asymmetric receptor material, a preparation method and a device application thereof, and belongs to the field of organic solar cells. Background Art

[0002] Organic solar cells, as a clean energy technology that converts solar energy into electrical energy, have attracted much attention in recent years in the context of global energy transformation. As an inexhaustible renewable energy source, the effective use of solar energy is crucial to alleviating the increasingly severe energy crisis and reducing dependence on traditional fossil energy. Organic solar cells stand out among many new energy technologies with their unique advantages, such as light weight, adjustable color and flexibility, showing great development potential. At the same time, achieving cheap, efficient and large-scale organic solar cells has always been the unremitting goal of scientific researchers and industry.

[0003] However, organic solar cells are currently facing many severe challenges in the process of industrialization. Among them, low photoelectric conversion efficiency and repeatability of battery devices have become the main bottlenecks hindering their large-scale commercial application. In the preparation process of solar cell devices, there are many influencing factors that lead to unstable device performance. For example, due to different production batches, the molecular structure and performance of polymer donor molecules will vary to a certain extent, which has a negative impact on the consistency and stability of the battery. In addition, additives usually play an important role in the preparation of organic solar cells. They can improve the morphology and crystallinity of the active layer, thereby improving the performance of the battery. However, mainstream additives such as chloronaphthalene are highly toxic, which not only poses a threat to the health of operators, but also greatly limits their scope of application due to environmental protection and safety considerations during the market promotion of products. At the same time, there are also large differences in the amount of additives added and the annealing process coordinated with the additives. The combined effect of these factors makes the batch repeatability of solar cell devices poor, which seriously affects product quality and production efficiency.

[0004] Therefore, the development of organic solar cells with high photoelectric conversion efficiency and no need for additive modification has extremely broad application prospects. The emergence of this new type of battery is of great significance for the preparation of low-cost, large-area organic solar cells and the promotion of large-scale commercial applications of organic solar cells. It can not only reduce production costs and potential harm to the environment, but also improve product stability and consistency, laying a solid foundation for the sustainable development of the organic solar cell industry. Summary of the invention

[0005] In view of the technical problem in the prior art that "organic solar cells have low photoelectric conversion efficiency and poor repeatability of battery devices", the purpose of the present invention is to provide a selenophene-thiophene fused-ring asymmetric acceptor material for organic solar cells and a preparation method and application, to prepare a high-efficiency, additive-free modified selenophene-thiophene fused-ring asymmetric acceptor material, which overcomes the shortcomings of additive toxicity and poor batch repeatability, and the solar cell efficiency exceeds 16.5%, showing the potential for large-scale commercial applications.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a selenophenothiophene fused ring asymmetric acceptor material for an organic solar cell, the structural formula of which is shown in Formula 1:

[0008]

[0009] Among them, the BO side chain is:

[0010] In a second aspect, the present invention also provides a method for preparing the selenophenothiophene fused ring asymmetric receptor material, comprising the following steps:

[0011] S1, reacting 3-bromothiophene, ethyl bromoacetate, butyl lithium and selenium powder to obtain intermediate product 1, subjecting intermediate product 1 to Friedel-Crafts reaction with 3-butylnonanoyl chloride to obtain intermediate product 2, and subjecting intermediate product 2 to tert-butyl alcohol ring closure, sodium hydroxide hydrolysis and Cu decarboxylation reaction in sequence to obtain 6-(2-butyloctyl)selenopheno[3,2-b]thiophene. The reaction process in step S1 is as follows;

[0012]

[0013] S2, reacting 3-(2-butyloctyl)thieno[3,2-b]thiophene, 6-(2-butyloctyl)selenopheno[3,2-b]thiophene, lithium diisopropylamide, and tin compound to obtain intermediate 3, reacting intermediate 3 with 4,7-dibromo-5,6-nitrobenz[c][1,2,5]thiadiazole, trisdibenzylideneacetone dipalladium, and tri-o-methylphenylphosphine to obtain intermediate 4, and reacting intermediate 4 with triphenylphosphine to obtain compound 1;

[0014] S3, reacting compound 1, 2-ethylhexyl bromide, potassium carbonate, potassium iodide and N,N-dimethylformamide (DMF) to obtain compound 2 (BTP-SSe);

[0015] S4, reacting compound 2 (BTP-SSe), tetrahydrofuran, lithium diisopropylamide, and DMF to obtain compound 3 (C12-CHO);

[0016] S5, reacting compound 3 (C12-CHO), fluorocyanoindanone, toluene, boron trifluoride etherate, and acetic anhydride to obtain the selenophenothiophene fused ring asymmetric receptor material (C12), and the reaction process in steps S2 to S5 is as follows;

[0017]

[0018] In the preferred solution, in step S1, the specific process is:

[0019] S11, add 3-bromothiophene and tetrahydrofuran to the reactor, evacuate the air under argon environment, dropwise add 1.1-1.2 equivalents of butyl lithium at -70--80°C, then slowly add 1.2-1.4 equivalents of selenium powder, return to -25--30°C and dropwise add ethyl bromoacetate, stir overnight, monitor the reaction progress by TLC, pour into water after the raw material disappears to stop the reaction, extract the aqueous phase with dichloromethane three times, dry with anhydrous sodium sulfate, remove the organic solvent by distillation under reduced pressure, and obtain a yellow liquid by column chromatography using a mixed solution of dichloromethane and n-hexane as eluent;

[0020] S12, adding the yellow liquid obtained in step S11 and dichloromethane (DCM) into a reactor, adding 1.1-1.2 equivalents of 3-butylnonanoyl chloride, slowly adding 1.2-1.3 equivalents of aluminum chloride, reacting for 3-5 hours, monitoring the reaction progress by TLC, pouring into water to stop the reaction after the raw material disappears, extracting the aqueous phase three times with dichloromethane, drying with anhydrous sodium sulfate, removing the organic solvent by reduced pressure distillation, and obtaining a yellow oily liquid by column chromatography using a mixed solution of dichloromethane and n-hexane as an eluent;

[0021] S13, adding the yellow oily liquid obtained in step S12 and tetrahydrofuran into a reactor, evacuating the air under an argon environment, dropping 1.1 to 1.2 equivalents of tert-butyl alcohol in tetrahydrofuran solution at -70 to -80°C, reacting for 3 to 5 hours, monitoring the reaction progress by TLC, adding ammonium chloride solution after the raw material disappears, pouring into water to stop the reaction, extracting the aqueous phase three times with dichloromethane, drying over anhydrous sodium sulfate, removing the organic solvent by distillation under reduced pressure, and obtaining a colorless liquid by column chromatography using a mixed solution of dichloromethane and n-hexane as an eluent;

[0022] S14, add the colorless liquid obtained in step S13 and ethanol into a reactor, add 2-4 equivalents of sodium hydroxide, stir at 70-80° C. overnight, monitor the reaction progress by TLC, pour into water to stop the reaction after the raw material disappears, extract the aqueous phase three times with dichloromethane, dry over anhydrous sodium sulfate, and remove the organic solvent by distillation under reduced pressure to obtain a yellow-white powder;

[0023] S15. Add the yellow-white powder obtained in step S14 and quinoline into a reactor, add 0.5 to 0.8 equivalent of copper powder and react for 2 to 4 hours. Monitor the reaction progress by TLC. After the raw material disappears, pour into water to stop the reaction. Extract the aqueous phase three times with dichloromethane, dry with anhydrous sodium sulfate, and remove the organic solvent by vacuum distillation. Use a mixed solution of n-hexane as an eluent to obtain a colorless liquid, i.e., 6-(2-butyloctyl)selenopheno[3,2-b]thiophene, by column chromatography.

[0024] In the preferred solution, in step S2, the specific process is:

[0025] S21, adding equal amounts of 3-(2-butyloctyl)thieno[3,2-b]thiophene and 6-(2-butyloctyl)selenopheno[3,2-b]thiophene into a reactor, and replacing the gas under an argon atmosphere;

[0026] S22, continue to add tetrahydrofuran, add 2 to 2.4 equivalents of lithium diisopropylamide at a low temperature of -60 to -80°C, then add 2.2 to 2.6 equivalents of tributyltin chloride, raise the temperature to -20 to -30°C and react for 3 to 4 hours; monitor the reaction progress by TLC, pour into water to stop the reaction after the raw material disappears, extract the aqueous phase with dichloromethane three times, dry with anhydrous sodium sulfate, and remove the organic solvent by distillation under reduced pressure to obtain intermediate 3;

[0027] S23, the intermediate product 3 and 0.8-1.0 equivalent of 4,7-dibromo-5,6-nitrobenzo[c][1,2,5]thiadiazole, 0.03-0.05 equivalent of trisdibenzylideneacetone dipalladium (Pd 2 (dba) 3 ), 0.3 to 0.4 equivalents of tri-o-methylphenylphosphine (P(o-tol) 3 ) and toluene via Stille coupling to obtain intermediate 4;

[0028] S24, intermediate product 4, 10 to 12 equivalents of triphenylphosphine (P(PPh) 3 and o-dichlorobenzene (DCB) were added into the reactor, the gas was replaced under argon atmosphere, the reaction was heated at 160-180° C. overnight, methanol was added and filtered to obtain compound 1.

[0029] In the preferred solution, in step S3, the specific process is:

[0030] S31, adding compound 1, 8 to 10 equivalents of 2-ethylhexyl bromide, 12 to 15 equivalents of potassium carbonate, and 0.3 to 0.4 equivalents of potassium iodide to a reactor, replacing the gas under an argon atmosphere, adding N,N-dimethylformamide under argon conditions, and heating the reaction at 100 to 110° C. overnight;

[0031] S32. Monitor the progress of the reaction by TLC. If the starting material disappears, pour it into water to stop the reaction. Extract the organic phase with petroleum ether, dry the organic phase with anhydrous sodium sulfate, remove the organic solvent under reduced pressure, and use n-hexane as the eluent to obtain compound 2 (BTP-SSe) as an orange-yellow transparent oil.

[0032] In the preferred solution, in step S4, the specific process is:

[0033] S41, add compound 2 to the reactor, replace the gas under argon, add 100-200 equivalents of N,N-dimethylformamide and tetrahydrofuran, add 10-15 equivalents of lithium diisopropylamide dropwise at -60--70°C, and stir for 3-4h;

[0034] S42. Monitor the progress of the reaction by TLC. If the starting material disappears, pour the mixture into water to stop the reaction. Extract the organic phase with dichloromethane. Dry the organic phase with anhydrous sodium sulfate. Remove the organic solvent under reduced pressure. Use dichloromethane and petroleum ether as eluents to obtain an orange-yellow compound 3 (C12-CHO).

[0035] In the preferred solution, in step S5, the specific process is:

[0036] S51, adding compound 3, 2 to 2.2 equivalents of fluorocyanoindanone and toluene to a reactor, and then adding about 0.1 equivalents of boron trifluoride etherate and acetic anhydride, and reacting for 1 to 2 hours;

[0037] S52, TLC monitors the reaction progress, and when the raw material disappears, the reaction is stopped by pouring into methanol. A purple-black solid is obtained after filtration, and dichloromethane and petroleum ether are used as eluents to obtain the selenophene-thiophene fused-ring asymmetric receptor material (C12).

[0038] In a third aspect, the present invention also provides the use of the selenophenothiophene fused-ring asymmetric acceptor material in an organic solar cell.

[0039] In some preferred embodiments, the electrode structure of the organic solar cell is: glass sheet / ITO / PEDOT:PSS / PM6:C12 / PDINN / Ag, wherein the glass sheet is the substrate, ITO is the positive electrode, PEDOT:PSS is the hole transport layer, the PM6:C12 blended film is the photoactive layer, PDINN is the electron transport layer, and Ag is the negative electrode.

[0040] In some preferred embodiments, the thickness of the active layer is 50 to 500 nm.

[0041] In some preferred embodiments, the photoactive layer is prepared as follows:

[0042] Dissolve the donor and acceptor materials in a solvent, with the mass ratio of donor to acceptor material being 1:1.2, and mix them evenly to obtain an active layer solution;

[0043] The active layer solution is spin-coated on the PEDOT:PSS layer, and the rotation speed is set to 1000-6000 r / min. After the spin coating is completed, annealing treatment is performed, the annealing temperature is 80-120°C, the annealing time is 5-20 min, and the product is obtained after cooling.

[0044] The present invention is the first to introduce a branched side chain, namely, 2-butyloctyl side chain substitution strategy, into the asymmetric acceptor unit of selenophene and thiophene, and at the same time simplifies the coupling process of asymmetric thiophene and [3,2-b] thiophene and selenophene and [3,2-b] thiophene units, greatly shortening the reaction steps and the corresponding post-processing time. The prepared asymmetric acceptor material C12 obtains a higher solar cell efficiency under the condition of no additive modification of the device, improves the batch repeatability of the device, and is expected to be applied in industrial production.

[0045] Compared with the prior art, the beneficial technical effects of the present invention are:

[0046] 1. The present invention adopts a type of non-fullerene acceptor material with good planarity, good film-forming property and low exciton binding energy. The material is characterized in that selenophene and thiophene fused ring units are introduced into the non-fullerene fused ring skeleton to make the material asymmetric, and the preparation process and time are saved by coupling the asymmetric units.

[0047] 2. The present invention adopts the branched side chain, namely 2-butyloctyl side chain substitution strategy for the first time in the selenophene-thiophene fused-ring asymmetric receptor material, thereby achieving a richer stacking pattern than that of straight-chain molecules and promoting the transfer of charges.

[0048] 3. The present invention provides a high-efficiency organic solar cell that does not require additives, the solar cell efficiency exceeds 16.5%, the cell batch repetition stability is improved and the cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of the absorption spectrum of the selenophenothiophene fused ring asymmetric acceptor material in Example 1;

[0050] Figure 2 The selenophene thiophene fused ring asymmetric receptor material in Example 1 1 H-NMR characterization;

[0051] Figure 3 The selenophene thiophene fused ring asymmetric receptor material in Example 1 13 C-NMR characterization;

[0052] Figure 4This is the current density-voltage characteristic curve of the additive-free modified organic solar cell in Example 2. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0054] The present invention will be further described below in conjunction with specific embodiments and drawings.

[0055] Example 1

[0056] A method for preparing a selenophenothiophene fused ring asymmetric receptor material comprises the following steps:

[0057] Step 1: react 3-bromothiophene, ethyl bromoacetate, butyl lithium and selenium powder to obtain intermediate 1, subject intermediate 1 to Friedel-Crafts reaction with 3-butylnonanoyl chloride to obtain intermediate 2, and subject intermediate 2 to tert-butyl alcohol ring closure, sodium hydroxide hydrolysis and Cu decarboxylation reaction in sequence to obtain 6-(2-butyloctyl)selenopheno[3,2-b]thiophene;

[0058] Step 1.1: 3-bromothiophene (10 g, 61.33 mmol) and 60 ml of anhydrous tetrahydrofuran were added to a 250 ml single-mouth bottle, and the mixture was evacuated three times under an argon atmosphere. Then, butyl lithium (26.98 ml, 67.5 mmol) was added dropwise at -78°C, and then selenium powder (5.81 g, 76.6 mmol) was slowly added. After the mixture was automatically warmed to -30°C, 68.5 ml of ethyl bromoacetate was added dropwise, and the mixture was stirred overnight. The reaction progress was monitored by TLC. After the raw material disappeared, the mixture was poured into water to stop the reaction. The aqueous phase was extracted with dichloromethane three times, dried over anhydrous sodium sulfate, and the organic solvent was removed by distillation under reduced pressure. A mixed solution of dichloromethane and n-hexane was used as the eluent, and a yellow liquid (10.7 g, 42.93 mmol) was obtained by column chromatography with a yield of 70%.

[0059] Step 1.2: Add the above yellow liquid (8.7 g, 34.91 mmol) and 80 ml of dichloromethane into a 250 ml single-mouth bottle, add 3-butylnonanoyl chloride (8.9 g, 38.4 mmol), slowly add aluminum chloride (5.35 g, 40.15 mmol), react for 3 h, monitor the reaction progress by TLC, pour into water to stop the reaction after the raw material disappears, extract the aqueous phase three times with dichloromethane, dry with anhydrous sodium sulfate, remove the organic solvent by vacuum distillation, use a mixed solution of dichloromethane and n-hexane as eluent, and obtain a yellow oily liquid (12.8 g, 28.73 mmol) by column chromatography, with a yield of 82.3%;

[0060] Step 1.3: The above yellow oily liquid (1 g, 2.24 mmol) and 15 ml of anhydrous tetrahydrofuran were added to a 100 ml single-mouth bottle, and the mixture was evacuated three times under an argon atmosphere. A tetrahydrofuran solution of tert-butyl alcohol (277 mg, 2.47 mmol) was then added dropwise at -78°C for three hours. The reaction progress was monitored by TLC. After the raw material disappeared, an ammonium chloride solution was added and the mixture was poured into water to stop the reaction. The aqueous phase was extracted three times with dichloromethane, dried over anhydrous sodium sulfate, and the organic solvent was removed by distillation under reduced pressure. A mixed solution of dichloromethane and n-hexane was used as the eluent, and a colorless liquid (662 mg, 1.55 mmol) was obtained by column chromatography with a yield of 69%.

[0061] Step 1.4: Add the above colorless liquid (6 g, 14 mmol) and ethanol to a 100 ml single-mouth bottle, add sodium hydroxide (1.68 g, 42 mmol), stir at 80°C overnight, monitor the reaction progress by TLC, pour into water to stop the reaction after the starting material disappears, extract the aqueous phase three times with dichloromethane, dry over anhydrous sodium sulfate, and remove the organic solvent by distillation under reduced pressure to obtain a yellow-white powder (4.77 g, 11.9 mmol), with a yield of 85%;

[0062] Step 1.5: In a 100 ml single-mouth bottle, add the above powder (4 g, 10 mmol) and 30 ml of quinoline, add copper powder (0.35 g, 5.5 mmol) and react for three hours. Monitor the reaction progress by TLC. After the raw material disappears, pour into water to stop the reaction. Extract the aqueous phase three times with dichloromethane, dry it with anhydrous sodium sulfate, and remove the organic solvent by vacuum distillation. Use a mixed solution of n-hexane as an eluent and obtain a colorless liquid (3.2 g, 9 mmol) by column chromatography. The yield is 90%.

[0063] Step 2: react 3-(2-butyloctyl)thieno[3,2-b]thiophene, 6-(2-butyloctyl)selenopheno[3,2-b]thiophene, lithium diisopropylamide, and tin compound to obtain intermediate 3, react intermediate 3 with 4,7-dibromo-5,6-nitrobenz[c][1,2,5]thiadiazole and trisdibenzylideneacetone dipalladium to obtain intermediate 4, and react intermediate 4 with tri-o-methylphenylphosphine to obtain compound 1;

[0064] Step 2.1: 3-(2-butyloctyl)thieno[3,2-b]thiophene (295 mg, 1 mmol) and 6-(2-butyloctyl)selenopheno[3,2-b]thiophene (340 mg, 1 mmol) were added to a 100 ml three-necked flask, and the gas was replaced three times under argon;

[0065] Step 2.2: Continue to add 20 ml of ultra-dry tetrahydrofuran, add lithium diisopropylamide (1.1 ml, 2.2 mmol) dropwise at -60°C, stir for 30 min, add tributyltin chloride (0.7 ml, 2.6 mmol), raise the temperature to -30°C and react for 3 h; monitor the reaction progress by TLC, pour into water to stop the reaction after the raw material disappears, extract the aqueous phase with dichloromethane three times, dry over anhydrous sodium sulfate, and remove the organic solvent by distillation under reduced pressure to obtain intermediate 3;

[0066] Step 2.3: Resuspend the intermediate 3 in 4,7-dibromo-5,6-nitrobenzo[c][1,2,5]thiadiazole (320 mg, 0.83 mmol), tris(dibenzylideneacetone)dipalladium (Pd2(dba) 3 )(38 mg, 0.042 mmol), tri-o-methylphenylphosphine (P(o-tol) 3 ) (101 mg, 0.332 mmol) was reacted with ultra-dry toluene by Stille coupling reaction, and the reaction was heated at 110°C for 12 h. After the raw material disappeared under TLC monitoring, the reaction was stopped by pouring into water. The aqueous phase was extracted with dichloromethane three times, and the organic solvent was removed by vacuum distillation. The intermediate product 4 was obtained by column chromatography using a mixed solution of dichloromethane and n-hexane as the eluent;

[0067] Step 2.4: Add the intermediate product 4, triphenylphosphine (4.92 g, 4.3 mmol) and o-dichlorobenzene into a 100 ml three-necked flask, replace the gas three times under argon atmosphere, heat the reaction at 160-180°C overnight, and after TLC monitoring the disappearance of the raw materials, pour into methanol to precipitate the product, and filter to obtain compound 1.

[0068] Step 3, reacting compound 1, o-dichlorobenzene, triphenylphosphine, 2-ethylhexyl bromide, potassium iodide, potassium carbonate and N,N-dimethylformamide (DMF) to obtain compound 2 (BTP-SSe);

[0069] Step 3.1: Add compound 1, 2-ethylhexyl bromide (551.2 mg, 2.86 mmol), potassium carbonate (740.2 mg, 5.355 mmol), and potassium iodide (21.3 mg, 0.13 mmol) to a 100 ml three-necked flask, replace the gas three times under argon atmosphere, add 15 mL of anhydrous N,N-dimethylformamide under argon condition, and heat the reaction at 100 ° C for 12 h;

[0070] Step 3.2: Monitor the progress of the reaction by TLC. When the starting material disappears, pour into water to stop the reaction. Extract the organic phase with petroleum ether three times (75 ml × 3). Dry the organic phase with anhydrous sodium sulfate, remove the organic solvent under reduced pressure, and use n-hexane as eluent to obtain the product BTP-SSe (265.4 mg, 0.25 mmol) as an orange-yellow transparent oil by column chromatography. The yield is 70%.

[0071] Step 4: reacting compound 2 (BTP-SSe), tetrahydrofuran, lithium diisopropylamide and DMF to obtain compound 3 (C12-CHO);

[0072] Step 4.1: Add BTP-SSe to a three-necked flask, replace the gas three times under argon, add anhydrous N,N-dimethylformamide (3.85 ml, 50 mmol) and 10 ml of tetrahydrofuran, add lithium diisopropylamide (1.25 ml, 2.5 mmol) dropwise at -60°C, and stir for 3 h;

[0073] Step 4.2: The reaction progress was monitored by TLC. When the starting material disappeared, the product was poured into water to stop the reaction. The organic phase was extracted with dichloromethane three times. The organic phase was dried over anhydrous sodium sulfate. The organic solvent was removed under reduced pressure and column chromatography was performed using dichloromethane and petroleum ether as eluents to obtain an orange solid C12-CHO (251 mg, 0.225 mmol) with a yield of 90%.

[0074] S5. Compound 3 (C12-CHO), fluorocyanoindanone, toluene, boron trifluoride etherate and acetic anhydride are reacted to obtain the selenophenothiophene fused ring asymmetric receptor material (C12).

[0075] Step 5.1: Add C12-CHO (100 mg, 0.089 mmol), fluorocyanoindanone (45.034 mg, 0.1958 mmol) and toluene to a single-necked bottle, then add boron trifluoride etherate (0.2 ml) and acetic anhydride, and react for 1 h;

[0076] Step 5.2: Monitor the reaction progress by TLC. If the starting material disappears, pour into methanol to stop the reaction. Filter to obtain a purple-black solid. Use dichloromethane and petroleum ether as eluents to obtain a selenophene-thiophene fused-ring asymmetric receptor material C12 (115.6 mg, 0.075 mmol).

[0077] Figure 1 This is a schematic diagram of the material absorption spectrum of the selenophene-thiophene fused-ring asymmetric acceptor material C12 in Example 1. It can be seen from the figure that C12 has achieved a relatively red-shifted absorption range, which is conducive to the generation of charges to obtain a higher current density, so that the additive-free device based on C12 achieves a higher energy conversion efficiency.

[0078] Figure 2 is the selenophene thiophene fused ring asymmetric receptor material C12 in Example 1 1 H-NMR characterization shows that the hydrogen atoms on the outer double bond of the C12 exocyclic ring and the two hydrogen atoms on the fluorocyanoindanone produce two sets of adjacent characteristic peaks in the aromatic region due to the asymmetric structure of C12, verifying the successful introduction of the asymmetric structure of C12.

[0079] Figure 3 is the selenophene thiophene fused ring asymmetric receptor material C12 in Example 1 13 C-NMR characterization shows that due to the asymmetry of partial replacement of S by Se in the skeleton, multiple groups of adjacent characteristic peaks appear, thus verifying the successful introduction of the asymmetric structure.

[0080] Application Example 1

[0081] The selenophenothiophene fused-ring asymmetric acceptor material (C12) prepared in Example 1 was applied to the preparation process of an organic solar cell.

[0082] The electrode structure of the organic solar cell is: glass sheet / ITO / PEDOT:PSS / PM6:C12 / PDINN / Ag, where the glass sheet is the substrate, ITO is the positive electrode, PEDOT:PSS is the hole transport layer, PM6:C12 blended film is the photoactive layer, PDINN is the electron transport layer, and Ag is the negative electrode.

[0083] The preparation process of the photoactive layer is as follows:

[0084] Dissolve the donor and acceptor materials in chloroform, with the mass ratio of donor to acceptor material being 1:1.2, and mix them evenly to obtain an active layer solution;

[0085] The active layer solution is spin-coated on the PEDOT:PSS layer, and the rotation speed is set to 1000-6000 r / min. After the spin coating is completed, annealing treatment is performed, the annealing temperature is 80-120°C, the annealing time is 5-20 min, and the product is obtained after cooling.

[0086] The preparation process of organic solar cells is:

[0087] The ITO glass was ultrasonically cleaned twice with deionized water and isopropanol, each time for about 15 minutes. After being blown dry with high-purity argon gas, the ITO glass was placed in a UV ozone cleaner and continued to be cleaned for 25 minutes. Subsequently, a thin layer of PEDOT:PSS film was applied to the cleaned ITO glass sheet by spin coating at a speed of 5000rpm for 30 seconds. Drying was carried out at 150°C for 15 minutes in an atmospheric atmosphere. Next, the active layer (16 mg / mL, donor-acceptor mass ratio 1:1.2) was spin coated on the PEDOT:PSS layer in a glove box (argon atmosphere) at 3000rpm for 30 seconds. The blended film was then thermally annealed at 100°C for 10 minutes. After cooling to room temperature, a layer of PDINN film (1 mg / mL, 3000rpm for 30 seconds) was spin coated on the active layer. Finally, at 1.5×10 -4 Under a vacuum of 1.3 Pa, a layer of Ag electrode with a thickness of about 100 nm is evaporated on the top of the battery.

[0088] Table 1: Device JV test curve parameters based on C12

[0089]

[0090] Figure 4 is the current density-voltage characteristic curve of the organic solar cell modified without additives in Example 2, Figure 4 It can be seen that when Jsc is zero, the open circuit voltage is 0.88V, and when Voc is zero, the short circuit current is 25.06. The JV curve is close to a rectangle, indicating that the device has obtained a higher fill factor and better morphology without additive modification.

[0091] In summary, organic solar cells with PM6:C12 as the active layer and no need for additive modification can achieve higher energy conversion efficiency. This result effectively overcomes the defects of low batch repeatability of devices, high pollution in the preparation process, and high cost, and has the advantages of large-scale preparation of organic solar cells, mass production and commercial application. Organic solar cells using selenophene thiophene fused ring asymmetric acceptors as the main component of the active layer have lower preparation costs, simpler process flow, and can obtain energy conversion efficiency exceeding 16.5%, which is of great significance to promoting the practical application of organic solar cells.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A selenophenothiophene fused ring asymmetric acceptor material for organic solar cells, characterized in that: Its structural formula is shown in Formula 1: Among them, the BO side chain is:

2. The method for preparing the selenophenothiophene fused-ring asymmetric receptor material according to claim 1, characterized in that: The following steps are involved: S1, reacting 3-bromothiophene, ethyl bromoacetate, butyl lithium and selenium powder to obtain intermediate product 1, subjecting intermediate product 1 to Friedel-Crafts reaction with 3-butylnonanoyl chloride to obtain intermediate product 2, and subjecting intermediate product 2 to tert-butyl alcohol ring closure, sodium hydroxide hydrolysis and Cu decarboxylation reaction in sequence to obtain 6-(2-butyloctyl)selenopheno[3,2-b]thiophene. The reaction process in step S1 is as follows; S2, reacting 3-(2-butyloctyl)thieno[3,2-b]thiophene, 6-(2-butyloctyl)selenopheno[3,2-b]thiophene, lithium diisopropylamide, and tin compound to obtain intermediate 3, reacting intermediate 3 with 4,7-dibromo-5,6-nitrobenz[c][1,2,5]thiadiazole, trisdibenzylideneacetone dipalladium, and tri-o-methylphenylphosphine to obtain intermediate 4, and reacting intermediate 4 with triphenylphosphine to obtain compound 1; S3, reacting compound 1, 2-ethylhexyl bromide, potassium carbonate, potassium iodide and N,N-dimethylformamide (DMF) to obtain compound 2 (BTP-SSe); S4, reacting compound 2 (BTP-SSe), tetrahydrofuran, lithium diisopropylamide, and DMF to obtain compound 3 (C12-CHO); S5, reacting compound 3 (C12-CHO), fluorocyanoindanone, toluene, boron trifluoride etherate, and acetic anhydride to obtain the selenophenothiophene fused ring asymmetric receptor material (C12), and the reaction process in steps S2 to S5 is as follows; 3. The method for preparing the selenophenothiophene fused-ring asymmetric receptor material according to claim 2, characterized in that: In step S1, the specific process is: S11, add 3-bromothiophene and tetrahydrofuran to the reactor, evacuate the air under argon environment, dropwise add 1.1-1.2 equivalents of butyl lithium at -70--80°C, then slowly add 1.2-1.4 equivalents of selenium powder, return to -25--30°C and dropwise add ethyl bromoacetate, stir overnight, monitor the reaction progress by TLC, pour into water after the raw material disappears to stop the reaction, extract the aqueous phase with dichloromethane three times, dry with anhydrous sodium sulfate, remove the organic solvent by distillation under reduced pressure, and obtain a yellow liquid by column chromatography using a mixed solution of dichloromethane and n-hexane as eluent; S12, adding the yellow liquid obtained in step S11 and dichloromethane (DCM) into a reactor, adding 1.1-1.2 equivalents of 3-butylnonanoyl chloride, slowly adding 1.2-1.3 equivalents of aluminum chloride, reacting for 3-5 hours, monitoring the reaction progress by TLC, pouring into water to stop the reaction after the raw material disappears, extracting the aqueous phase three times with dichloromethane, drying with anhydrous sodium sulfate, removing the organic solvent by reduced pressure distillation, and obtaining a yellow oily liquid by column chromatography using a mixed solution of dichloromethane and n-hexane as an eluent; S13, adding the yellow oily liquid obtained in step S12 and tetrahydrofuran into a reactor, evacuating the air under an argon environment, dropping 1.1 to 1.2 equivalents of tert-butyl alcohol in tetrahydrofuran solution at -70 to -80°C, reacting for 3 to 5 hours, monitoring the reaction progress by TLC, adding ammonium chloride solution after the raw material disappears, pouring into water to stop the reaction, extracting the aqueous phase three times with dichloromethane, drying over anhydrous sodium sulfate, removing the organic solvent by distillation under reduced pressure, and obtaining a colorless liquid by column chromatography using a mixed solution of dichloromethane and n-hexane as an eluent; S14, add the colorless liquid obtained in step S13 and ethanol into a reactor, add 2-4 equivalents of sodium hydroxide, stir at 70-80° C. overnight, monitor the reaction progress by TLC, pour into water to stop the reaction after the raw material disappears, extract the aqueous phase three times with dichloromethane, dry over anhydrous sodium sulfate, and remove the organic solvent by distillation under reduced pressure to obtain a yellow-white powder; S15. Add the yellow-white powder obtained in step S14 and quinoline into a reactor, add 0.5 to 0.8 equivalent of copper powder and react for 2 to 4 hours. Monitor the reaction progress by TLC. After the raw material disappears, pour into water to stop the reaction. Extract the aqueous phase three times with dichloromethane, dry with anhydrous sodium sulfate, and remove the organic solvent by vacuum distillation. Use a mixed solution of n-hexane as an eluent to obtain a colorless liquid, i.e., 6-(2-butyloctyl)selenopheno[3,2-b]thiophene, by column chromatography.

4. The method for preparing the selenophenothiophene fused-ring asymmetric receptor material according to claim 2, characterized in that: In step S2, the specific process is: S21, adding equal amounts of 3-(2-butyloctyl)thieno[3,2-b]thiophene and 6-(2-butyloctyl)selenopheno[3,2-b]thiophene into a reactor, and replacing the gas under an argon atmosphere; S22, continue to add tetrahydrofuran, add 2 to 2.4 equivalents of lithium diisopropylamide at a low temperature of -60 to -80°C, then add 2.2 to 2.6 equivalents of tributyltin chloride, raise the temperature to -20 to -30°C and react for 3 to 4 hours; monitor the reaction progress by TLC, pour into water to stop the reaction after the raw material disappears, extract the aqueous phase with dichloromethane three times, dry with anhydrous sodium sulfate, and remove the organic solvent by distillation under reduced pressure to obtain intermediate 3; S23, reacting the intermediate 3 with 0.8-1.0 equivalent of 4,7-dibromo-5,6-nitrobenz[c][1,2,5]thiadiazole, 0.03-0.05 equivalent of trisdibenzylideneacetone dipalladium (Pd2(dba)3), 0.3-0.4 equivalent of tri-o-methylphenylphosphine (P(o-tol)3) and toluene (Toluene) by stille coupling to obtain the intermediate 4; S24, add the intermediate product 4, 10-12 equivalents of triphenylphosphine (P(PPh)3) and o-dichlorobenzene (DCB) into a reactor, replace the gas under argon atmosphere, heat the reaction at 160-180°C overnight, add methanol and filter to obtain compound 1.

5. The method for preparing the selenophenothiophene fused-ring asymmetric receptor material according to claim 2, characterized in that: In step S3, the specific process is: S31, adding compound 1, 8 to 10 equivalents of 2-ethylhexyl bromide, 12 to 15 equivalents of potassium carbonate, and 0.3 to 0.4 equivalents of potassium iodide to a reactor, replacing the gas under an argon atmosphere, adding N,N-dimethylformamide under argon conditions, and heating the reaction at 100 to 110° C. overnight; S32. Monitor the progress of the reaction by TLC. If the starting material disappears, pour it into water to stop the reaction. Extract the organic phase with petroleum ether, dry the organic phase with anhydrous sodium sulfate, remove the organic solvent under reduced pressure, and use n-hexane as the eluent to obtain compound 2 (BTP-SSe) as an orange-yellow transparent oil.

6. The method for preparing the selenophenothiophene fused-ring asymmetric receptor material according to claim 2, characterized in that: In step S4, the specific process is: S41, add compound 2 to the reactor, replace the gas under argon, add 100-200 equivalents of N,N-dimethylformamide and tetrahydrofuran, add 10-15 equivalents of lithium diisopropylamide dropwise at -60--70°C, and stir for 3-4h; S42. Monitor the progress of the reaction by TLC. If the starting material disappears, pour the mixture into water to stop the reaction. Extract the organic phase with dichloromethane. Dry the organic phase with anhydrous sodium sulfate. Remove the organic solvent under reduced pressure. Use dichloromethane and petroleum ether as eluents to obtain an orange-yellow compound 3 (C12-CHO).

7. The method for preparing the selenophenothiophene fused-ring asymmetric receptor material according to claim 2, characterized in that: In step S5, the specific process is: S51, adding compound 3, 2 to 2.2 equivalents of fluorocyanoindanone and toluene to a reactor, and then adding 0.1 equivalents of boron trifluoride etherate and acetic anhydride, and reacting for 1 to 2 hours; S52, TLC monitors the reaction progress, and when the raw material disappears, the reaction is stopped by pouring into methanol. A purple-black solid is obtained after filtration, and dichloromethane and petroleum ether are used as eluents to obtain the selenophene-thiophene fused-ring asymmetric receptor material (C12).

8. Use of the selenophenothiophene fused-ring asymmetric acceptor material according to any one of claims 1 to 7 in an organic solar cell.

9. The use of the selenophenothiophene fused-ring asymmetric acceptor material in an organic solar cell according to claim 8, characterized in that: The electrode structure of the organic solar cell is: glass sheet / ITO / PEDOT:PSS / PM6:C12 / PDINN / Ag, wherein the glass sheet is the substrate, ITO is the positive electrode, PEDOT:PSS is the hole transport layer, the PM6:C12 blended film is the photoactive layer, PDINN is the electron transport layer, and Ag is the negative electrode.

10. The use of the selenophenothiophene fused ring asymmetric acceptor material in an organic solar cell according to claim 8, characterized in that: The thickness of the active layer is 50 to 500 nm; The preparation process of the photoactive layer is as follows: Dissolve the donor and acceptor materials in a solvent, with the mass ratio of donor to acceptor material being 1:1.2, and mix them evenly to obtain an active layer solution; The active layer solution is spin-coated on the PEDOT:PSS layer, and the rotation speed is set to 1000-6000 r / min. After the spin coating is completed, annealing treatment is performed, the annealing temperature is 80-120°C, the annealing time is 5-20 min, and the product is obtained after cooling.

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