A class of a-d-a type polymeric photovoltaic material based on porphyrin and preparation method and application thereof

Abstract

This invention discloses a class of porphyrin-based A-D-A type polymer photovoltaic materials, their preparation methods, and applications. The invention utilizes a porphyrin-DPP system constructed through Sonogashira coupling, placing the donor unit at the center of the A-D-A structure. This A-D-A structure more effectively enhances the intramolecular push-pull electronic effect, promoting intramolecular charge transfer and thus significantly broadening and redshifting the light absorption range of the polymer. Furthermore, the A-D-A structure facilitates more ordered and compact intermolecular stacking, promoting the expansion of π-π conjugation and potentially increasing the carrier mobility of the material. This lays the material foundation for obtaining higher short-circuit current densities and fill factors in devices.

Description

Technical Field

[0001] This invention belongs to the field of organic polymer photovoltaic materials, specifically relating to a class of conjugated polymers obtained by polymerization via Sonogashira coupling reaction using porphyrins modified with specific side chains as donor units and pyrrolopyrrole dione (DPP) as acceptor units. More specifically, this invention relates to ADA-type polymers and their preparation methods, as well as the significant advantages of this ADA-type structure in improving polymer photovoltaic performance, especially short-circuit current density and photoelectric conversion efficiency. Background Technology

[0002] Organic solar cells (OSCs) have attracted much attention due to their advantages such as highly designable material structures, solution-processability, and suitability for fabricating flexible and lightweight devices. The core of the device is the active layer, which is usually composed of a blend of electron donor (p-type) and electron acceptor (n-type) materials. Developing donor materials with broad-spectrum absorption, suitable energy level matching, and high charge transport capabilities is key to improving photoelectric conversion efficiency (PCE).

[0003] Porphyrins are a class of rigid molecules with large π-conjugated planes, possessing strong electron-donating ability, high molar extinction coefficients, and excellent optical / thermal stability, making them ideal building blocks for constructing high-performance polymer donors. By functionalizing the meso sites surrounding porphyrins with alkyne bonds, DA structures with excellent planarity and conjugation can be constructed. However, traditional DA-type linear polymers, which connect porphyrin donor and acceptor units with alkyne bonds, still have significant room for improvement in terms of intramolecular charge transfer (ICT) intensity, optical absorption range, and ultimately, device efficiency.

[0004] Pyrrolopyrroledione (DPP), as a classic strong electron-withdrawing acceptor unit, often exhibits strong ICT effects in its DA polymers. The Sonogashira coupling reaction, which links meso-alkynylated porphyrins to brominated DPP units, is an efficient polymerization strategy.

[0005] Therefore, designing and synthesizing polymers with well-defined side-chain structures (porphyrin units with phenoxy side chains and DPP units with 2-ethylhexyl side chains), and thoroughly studying the influence of structural evolution on the photoelectric properties and device performance of materials, is of great theoretical and practical significance for the development of next-generation high-performance porphyrin-based polymer donor materials. Summary of the Invention

[0006] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a class of porphyrin-based ADA-type polymer photovoltaic materials.

[0007] Another object of the present invention is to provide a method for preparing the above-mentioned type of porphyrin-based ADA-type polymer photovoltaic materials.

[0008] Another object of the present invention is to provide the application of the above-mentioned porphyrin-based ADA-type polymer photovoltaic materials as donor materials in organic solar cells.

[0009] To achieve this objective, the present invention employs the following technical solution:

[0010] In a first aspect, the present invention provides a class of porphyrin-based ADA-type polymer photovoltaic materials having the structural formula shown in formula (Ⅰ):

[0011]

[0012] (I)

[0013] Wherein, R1 is an alkyl group with 12 to 16 carbon atoms; R2 is an alkyl group with 8 to 16 carbon atoms, and n is 7 to 13.

[0014] Preferably, R1 is at least one of 2-hexyldecyl and n-hexadecyl.

[0015] Preferably, R2 is at least one of 2-ethylhexyl and n-octyl.

[0016] Secondly, the present invention provides a method for preparing the above-mentioned ADA-type polymer photovoltaic material based on porphyrin, comprising the following steps:

[0017] (1) Dissolve 3,4,5-trihydroxybenzaldehyde and alkyl bromide in an organic solvent and react at 60-70°C for 12-24 hours under the action of a catalyst to obtain compound (II);

[0018]

[0019] (II)

[0020] (2) Compound (II) and dipyrrolemethane were dissolved in an organic solvent, and trifluoroacetic acid was added under light-protected conditions. The reaction was carried out at room temperature for 10 to 16 hours. Then 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) was added, and the reaction was continued for 0.5 to 3 hours to obtain compound (III).

[0021]

[0022] (III) (IV)

[0023] (3) Dissolve compound (Ⅲ) in an organic solvent, add N-bromosuccinimide (NBS) at low temperature and react for 0.3 to 0.7 hours, then continue the reaction at room temperature for 0.5 to 5 hours to obtain compound (Ⅳ);

[0024] (4) Dissolve compound (Ⅳ) in an organic solvent, add zinc acetate, react at 40-60°C for 0.5-2 hours, and then react at room temperature for 12-24 hours to obtain compound (Ⅴ).

[0025]

[0026] (V) (VI)

[0027] (5) Dissolve compound (V) in an organic solvent, add trimethylsilyl acetylene, and react at 60-100°C for 12-48 hours under the action of a catalyst to obtain compound (VI).

[0028] (6) Dissolve the monobromine-containing pyrrolopyrrole dione derivative and pinacol diboronic acid in an organic solvent and react at 60-100°C for 48-72 hours under the action of a catalyst to obtain compound (VII).

[0029]

[0030] (VII) (VIII)

[0031] (7) Dissolve compound (VII) in an organic solvent, add N-bromosuccinimide (NBS) at low temperature and react for 0.5 to 3 hours to obtain compound (VIII);

[0032] (8) Dissolve compound (VI) in an organic solvent, add tetrabutylammonium fluoride solution at room temperature, stir for 5 to 30 minutes, quench with water to stop the reaction, extract, and evaporate to dryness to obtain compound (IX).

[0033]

[0034] (IX)

[0035] (9) Dissolve compounds (IX) and (VIII) in an organic solvent and heat under reflux for 48 to 72 hours in the presence of a catalyst to obtain the target ADA type polymer.

[0036] The definitions of R1 and R2 are the same as those in the above-mentioned ADA-type polymer photovoltaic material structure based on porphyrin.

[0037] Preferably, the organic solvent in step (1) is N,N-dimethylformamide.

[0038] Preferably, the ratio of 3,4,5-trihydroxybenzaldehyde to organic solvent in step (1) is 1 mmol: 3-8 ml.

[0039] Preferably, the molar ratio of 3,4,5-trihydroxybenzaldehyde and alkyl bromide in step (1) is 1:3 to 1:5.

[0040] Preferably, the catalyst in step (1) is anhydrous potassium carbonate and potassium iodide; the molar amount of anhydrous potassium carbonate is 2 to 4 times the molar amount of 3,4,5-trihydroxybenzaldehyde, more preferably 3 times, and the molar amount of potassium iodide is 0.05 to 0.2 times the molar amount of 3,4,5-trihydroxybenzaldehyde, more preferably 0.1 times.

[0041] Preferably, the organic solvent in step (2) is one of chloroform and dichloromethane.

[0042] Preferably, the ratio of compound (II) to organic solvent in step (2) is 1 mmol: 60-120 ml.

[0043] Preferably, the molar ratio of compound (II) and dipyrrolemethane in step (2) is 1:1 to 1:2.

[0044] Preferably, the molar amount of trifluoroacetic acid in step (2) is 0.2 to 0.6 times that of compound (II), more preferably 0.4 times.

[0045] Preferably, the molar amount of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in step (2) is 1.5 to 2.0 times that of compound (II), more preferably 1.7 times.

[0046] Preferably, the organic solvent in step (3) is at least one of chloroform and dichloromethane.

[0047] Preferably, the ratio of compound (Ⅲ) to organic solvent in step (3) is 1 mmol: 400-800 ml.

[0048] Preferably, the molar ratio of compound (Ⅲ) to N-bromosuccinimide in step (3) is 1:2 to 1:4.

[0049] Preferably, the low temperature in step (3) should be controlled between -10 and 0°C.

[0050] Preferably, the organic solvent in step (4) is a mixture of at least one of chloroform and dichloromethane with methanol; the molar amount of at least one of chloroform and dichloromethane is 500 to 3000 times the molar amount of compound (IV), and the volume ratio of at least one of chloroform and dichloromethane to methanol is 6:1 to 3:1.

[0051] Preferably, the molar ratio of compound (Ⅳ) to zinc acetate in step (4) is 1:2 to 1:10.

[0052] Preferably, the organic solvent in step (5) is a mixed solvent of tetrahydrofuran and triethylamine; the molar amount of tetrahydrofuran is 500 to 2000 times the molar amount of compound (V), and the volume ratio of tetrahydrofuran to triethylamine is 2:1 to 5:1.

[0053] Preferably, the molar ratio of compound (V) to trimethylsilylacetylene in step (5) is 1:4 to 1:6.

[0054] Preferably, the catalyst in step (5) is bis(triphenylphosphine)palladium dichloride and cuprous iodide; the molar amount of both is 0.05 to 0.2 times the molar amount of compound (V), more preferably 0.1 times.

[0055] Preferably, the molar ratio of the monobrominated pyrrolopyrrole dione derivative and pinacol diboronic acid ester in step (6) is 1:0.8 to 1:1.

[0056] Preferably, the organic solvent in step (6) is tetrahydrofuran, and the molar amount is 200 to 500 times the molar amount of the pyrrolopyrrole dione derivative containing monobromine.

[0057] Preferably, the catalyst in step (6) is anhydrous potassium carbonate and tetra(triphenylphosphine)palladium; the molar amount of anhydrous potassium carbonate is 3 to 5 times the molar amount of the monobrominated pyrrolopyrrole dione derivative, and the molar amount of tetra(triphenylphosphine)palladium is 0.01 to 0.1 times the molar amount of the monobrominated pyrrolopyrrole dione derivative, more preferably 0.05 times; more preferably, the anhydrous potassium carbonate can be dissolved in deionized water first to prepare a 2 mol / L solution.

[0058] Preferably, the organic solvent in step (7) is chloroform.

[0059] Preferably, the ratio of (VII) to organic solvent in step (7) is 1 mmol: 500-600 ml.

[0060] Preferably, the molar ratio of compound (VII) to N-bromosuccinimide in step (7) is 1:2 to 1:2.5.

[0061] Preferably, the low temperature in step (7) should be controlled between -10 and 0°C.

[0062] Preferably, the organic solvent in step (8) is tetrahydrofuran; the molar amount of tetrahydrofuran is 2000 to 4000 times the molar amount of compound (VI).

[0063] Preferably, the molar ratio of compound (VI) to tetrabutylammonium fluoride in step (8) is 1:3 to 1:5.

[0064] Preferably, the concentration of the tetrabutylammonium fluoride solution in step (8) is 0.5 to 1.5 mol / L, and the solvent is tetrahydrofuran.

[0065] Preferably, the molar ratio of compound (IX) and compound (VIII) in step (9) is 1:1 to 1:2.

[0066] Preferably, the organic solvent in step (9) is a mixed solvent of tetrahydrofuran and triethylamine; the molar amount of tetrahydrofuran is 2000 to 3000 times the molar amount of compound (IX), and the volume ratio of tetrahydrofuran to triethylamine is 2:1 to 5:1.

[0067] Preferably, the catalyst in step (9) is tetra(triphenylphosphine)palladium and cuprous iodide; the molar amount of tetra(triphenylphosphine)palladium is 0.1 to 0.5 times the molar amount of compound (IX), more preferably 0.2 times; the molar amount of cuprous iodide is 0.25 to 0.3 times the molar amount of compound (IX).

[0068] Preferably, the temperature of the heating reflux in step (9) is 60-80°C.

[0069] Thirdly, the present invention provides the application of the above-mentioned porphyrin-based ADA-type polymer photovoltaic materials as electron donor materials for the preparation of active layers of organic solar cells.

[0070] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0071] (1) This invention designs and synthesizes ADA-type polymers based on identical side chain modifications and identical coupling methods (Sonogashira coupling), providing an accurate control system for studying structure-property relationships.

[0072] (2) Compared with the traditional DA alternating structure, the ADA type structure proposed in this invention can more effectively enhance the intramolecular "push-pull" electronic effect and promote intramolecular charge transfer (ICT), thereby significantly broadening and redshifting the light absorption range of polymers and more finely controlling their frontier molecular orbital energy levels.

[0073] (3) The ADA-type structure of the present invention helps to form a more ordered and compact intermolecular stacking, which is conducive to the expansion of π-π conjugation, thereby potentially improving the carrier mobility of the material and laying the material basis for obtaining higher device short-circuit current density and fill factor.

[0074] (4) This invention demonstrates through direct comparison that, for the porphyrin and DPP system constructed by Sonogashira coupling, placing the donor unit at the center of the ADA structure is an efficient molecular design strategy that breaks through the performance bottleneck of traditional polymer DA structures and significantly improves photovoltaic performance. Attached Figure Description

[0075] Figure 1 The image shows the room-temperature GPC spectrum of Comparative Example 1.

[0076] Figure 2 This is the room temperature GPC spectrum of Example 1.

[0077] Figure 3 The UV-Vis absorption spectra of the solution and the thin film in Comparative Example 1 are shown.

[0078] Figure 4 The UV-Vis absorption spectra of the solution and film in Example 1 are shown.

[0079] Figure 5 This is the cyclic voltammetry curve for Comparative Example 1.

[0080] Figure 6 This is the cyclic voltammetry curve for Example 1.

[0081] Figure 7 Photovoltaic cells prepared from the materials obtained in Example 1 and Comparative Example 1 were tested at AM 1.5 and 100 mW / cm². 2 Current-voltage curve under illumination.

[0082] Figure 8 The device electron mobility device J of the materials obtained in Example 1 and Comparative Example 1 1 / 2 -V fitted straight line.

[0083] Figure 9 Device J, which is a hole mobility device based on the materials obtained in Example 1 and Comparative Example 1. 1 / 2 -V fitted straight line. Detailed Implementation

[0084] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0085] Unless otherwise specified in the embodiments of this invention, the conditions shall be performed according to conventional conditions or conditions recommended by the manufacturer. All raw materials and reagents used, unless otherwise specified, are commercially available conventional products.

[0086] Comparative Example 1

[0087] Synthesis of DA-type polymers PZPTDPPT

[0088] The reaction process in Example 1 is as follows:

[0089]

[0090]

[0091] (1) In a two-necked reaction flask, 104 mL (1.45 mol) of freshly distilled pyrrole and 23 mL of 37% formaldehyde aqueous solution were added sequentially, and the mixture was placed under thorough stirring. Then, the reaction system was heated to 65°C and maintained for 5 minutes, after which heating was stopped and the oil bath was removed. After the system cooled slightly, 2.3 mL of trifluoroacetic acid was slowly added dropwise in several portions, and the reaction was continued for 5 minutes after the addition was completed. After the reaction was completed, 300 mL of 40% NaOH aqueous solution was added to quench the reaction. The reaction solution was washed twice with distilled water and extracted twice with DCM. The organic phases were combined and concentrated by rotary evaporation. The product was transferred to a small round-bottom flask. Then, vacuum distillation was carried out by an oil pump. First, excess unreacted pyrrole was removed. If the temperature was increased further, a small amount of impurities could be distilled off. If the temperature was increased further, a fraction was distilled off and quickly condensed into a white solid. After the distillation process was completed, 4.45 g of white solid product with a candle-like appearance was collected, which is intermediate 1. The final product was wrapped in aluminum foil and stored in the freezer.

[0092] (2) In a Slink flask, a mixture of 3,4,5-trihydroxybenzaldehyde (616 mg, 4.0 mmol), hexadecyl bromide (5.49 g, 18 mmol), anhydrous potassium carbonate (1.66 g, 12 mmol), and potassium iodide (66.4 mg, 0.4 mmol) dissolved in 20 mL of ultradry N,N-dimethylformamide was stirred at 70 °C for 14 hours. After cooling to room temperature, the reaction solution was mixed with water, and the aqueous phase was extracted with DCM. The organic phases were combined and washed successively with saturated brine and anhydrous sodium sulfate and dried. After removing the solvent by rotary evaporation, preliminary purification was carried out by column chromatography using a petroleum ether / dichloromethane (3:1, v / v) mixed solvent as the eluent to obtain intermediate 2.

[0093] Under an argon atmosphere, intermediate 2 (2.0 g, 3.32 mmol) and intermediate 1 (0.49 g, 3.32 mmol) were added to a reaction flask, along with 300 mL of dichloromethane. The mixture was protected from light, and then 0.09 mL of trifluoroacetic acid was slowly added dropwise. The solution gradually turned deep red. The reaction was then stirred at room temperature for 14 hours, followed by the addition of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) (1.26 g, 5.53 mmol). Stirring was continued at room temperature for another hour, followed by the addition of 1 mL of triethylamine to quench the reaction. The liquid was then directly poured into a dry silica gel column for column chromatography, using dichloromethane as the eluent. After removing the solvent by rotary evaporation, the solution was purified by column chromatography using a petroleum ether / dichloromethane (3:1, v / v) mixture as the eluent. The solvent was then evaporated by rotary evaporation to obtain 747 mg of intermediate 3 as an oil, with a yield of 20%.

[0094] (3) Intermediate 3 (373.5 mg, 0.20 mmol) was dissolved in 100 ml of chloroform, and 8.4 ml of pyridine was added. The mixture was then cooled to 0 °C. NBS (105.3 mg, 0.49 mmol) was then added, and the mixture was stirred at 0 °C for 30 minutes. The mixture was then removed and reacted at room temperature in the dark for 4 hours, followed by quenching with acetone. The solvent was directly evaporated, and the mixture was loaded with silica gel powder and purified by column chromatography using petroleum ether / dichloromethane at a ratio of 3:1 as the eluent. The mixture was evaporated and dried under vacuum overnight to obtain 393.6 mg of intermediate 4, which was a viscous, dark liquid with a yield of 95%.

[0095] (4) Intermediate 4 (393.6 mg, 0.19 mmol) was dissolved in 30 mL of chloroform, and then 5 mL of methanol solution containing zinc acetate (84.5 mg, 0.46 mmol) was added. The mixture was heated at 50 °C for 2 hours, then the heating plate was removed and the mixture was allowed to react at room temperature for 12 hours. The solvent was removed by direct rotary evaporation, and the mixture was poured into a silica gel column containing dry silica gel powder. Dichloromethane was used as the eluent. The mixture was then evaporated by rotary evaporation and dried under vacuum to obtain 404 mg of intermediate 5, which was a viscous, dark liquid with a yield of 100%.

[0096] (5) Under an argon atmosphere, intermediate 5 (404 mg, 0.19 mmol) was dissolved in 12 mL of ultra-dry tetrahydrofuran and 6 mL of ultra-dry triethylamine, and placed in a Slink flask. Then, Pd(PPh3)2Cl2 (13.52 mg, 0.019 mmol) and CuI (3.68 mg, 0.019 mmol) were added. Subsequently, trimethylsilylacetylene (94.37 mg, 0.96 mmol) was added. The mixture was then stirred at 60°C in the dark for 24 hours. Afterward, distilled water was added to quench the reaction. The mixture was extracted three times with dichloromethane, washed with water, and dried. The solvent was removed, and the mixture was purified by column chromatography with dichloromethane / petroleum ether (1:3) as the eluent to obtain 386 mg of intermediate 6 as a dark purple viscous liquid, with a yield of 92%.

[0097] (6) Dissolve intermediate 6 (68.9 mg, 0.032 mmol) in 10 ml tetrahydrofuran, then add 0.1 ml tetrabutylammonium fluoride (1 mol / L tetrahydrofuran solution), stir the reaction for 5 minutes, then add distilled water to quench the reaction, extract twice with DCM, wash with water, evaporate at low temperature, and purify by column chromatography, using chloroform / petroleum ether (3:1) as the eluent, and finally obtain a purple-green viscous liquid 7.

[0098] Under an argon atmosphere, intermediate 7 (64.3 mg, 0.032 mmol), intermediate a (21.8 mg, 0.032 mmol), and a mixture of ultra-dry tetrahydrofuran (6 mL) and ultra-dry triethylamine (2 mL) were added sequentially to a 50 mL Slinker flask. Catalytic amounts of cuprous iodide (1.6 mg, 0.0085 mmol) and tetra(triphenylphosphine)palladium (7.4 mg, 0.0064 mmol) were also added. The reaction mixture was stirred continuously at 70 °C for 72 hours in the dark. After the reaction was complete, the mixture was cooled to room temperature and extracted multiple times with dichloromethane. The combined organic phases were concentrated using a rotary evaporator to remove the solvent, then passed through a dry silica gel column. The resulting solution was further evaporated by rotary evaporation to remove the solvent. The crude product was redissolved in a small amount of DCM and then slowly poured into a large volume of methanol to precipitate a black solid. The precipitate was collected by filtration and then extracted sequentially with methanol and acetone in a Soxhlet extractor for one day each to remove oligomer impurities. The target product component solution was then obtained by chloroform extraction and dissolution. Finally, recrystallization was performed using DCM and methanol to obtain 38 mg of the target black solid product PZPTDPPT, with a yield of 44%. GPC: Mn = 20.1 kg•mol -1 Mw = 48.6 kg•mol -1 PDI=2.42.

[0099] The porphyrin-based polymer photovoltaic material PZPTDPPT prepared in this comparative example was dissolved in chloroform solution, and its molar concentration was (10) -5 -10 -4 The UV-Vis absorption spectrum of the resulting chloroform solution (mol / L) is shown in the figure. Figure 3 .

[0100] The porphyrin-based polymer photovoltaic material prepared in this comparative example was spin-coated into a thin film with a thickness of approximately 70 nm. The UV-Vis absorption spectrum of the film is shown below. Figure 3 .

[0101] The donor photovoltaic material prepared in this comparative example was tested for electrochemical performance using cyclic voltammetry (CV) on an electrochemical workstation. The cyclic voltammetry curves are shown in the figure. Figure 5 .

[0102] Using the porphyrin polymer molecule from this comparative example as the donor material and the small molecule Y6 (CAS: 2304444-49-1) as the acceptor material, a front-mounted device was fabricated to study its photovoltaic performance. The device structure is ITO / PEDOT:PSS / active layer / Phen-NaDPO / Ag, with a donor-acceptor mass ratio of 1:2 in the active layer. The current-voltage curve (JV curve) under illumination is shown in [Figure number missing]. Figure 7 The fabricated device exhibits a photoelectric conversion efficiency of 1.07% and a short-circuit current of 5.44 mA / cm². 2 The open-circuit voltage is 0.60V and the fill factor is 32.93%.

[0103] The photoelectric conversion efficiency achieved by the heterojunction solar cell prepared in this comparative example is the highest photoelectric conversion efficiency obtained by using an active layer material prepared with an optimized donor-acceptor ratio of 1:2 and CS2 steam thermal annealing.

[0104] Example 1

[0105] Synthesis of ADA-type polymer PZPDTDPPT

[0106]

[0107] (1) Under argon protection, DPP-Br (250 mg, 0.414 mmol), pinacol diborate (52.6 mg, 0.21 mmol), and tetra(triphenylphosphine)palladium (23.9 mg, 0.021 mmol) were placed in a Slinker flask. Then, 10 mL of tetrahydrofuran and 0.7 mL of anhydrous potassium carbonate solution (2 mol / L) were added. The system was degassed using a double-row tube and reacted at 75 °C for 72 hours in the dark. Pinacol diborate was added twice during the reaction (17.5 mg, 0.069 mmol each time) to continue the reaction. After the reaction was complete, the mixture was cooled to room temperature, quenched with distilled water, and the aqueous phase was extracted with dichloromethane. The organic phase was washed with brine and concentrated by rotary evaporation. Purification was performed by silica gel column chromatography, using petroleum ether:dichloromethane (1:1, v / v) and dichloromethane as eluents sequentially. The target fraction was collected, the solvent was removed by rotary evaporation, and further purification was performed by GPC gel column chromatography using tetrahydrofuran as eluent. Then, recrystallization was performed using DCM and methanol to finally obtain 158.2 mg of intermediate b, which was a blue-purple solid product with a yield of 73%.

[0108] (2) Under light-protected conditions, intermediate b (54 mg, 0.052 mmol) was dissolved in 30 mL of chloroform and cooled and stirred at -10 °C. Then, a solution of NBS (18.8 mg, 0.11 mmol) dissolved in chloroform was slowly added dropwise, and the reaction was continued under darkness with stirring. The reaction was monitored using a TLC plate every 10 minutes. During the reaction, the temperature was gradually increased to 10 °C. After 2 hours, 30 mL of distilled water was added to quench the reaction mixture, and the aqueous phase was extracted with dichloromethane. The organic phases were combined, washed with brine, and rotary evaporated to obtain the crude product. First, petroleum ether:dichloromethane (3:1, v / v) was used as the eluent, and then the polarity was gradually increased until pure dichloromethane was used for elution, and the target component was collected. After removing the solvent by rotary evaporation, tetrahydrofuran was used as the eluent for further purification by GPC gel column chromatography. Then, DCM and methanol were used for multiple recrystallizations to finally obtain 51 mg of intermediate c, which was a blue solid product with a yield of 81%.

[0109] (3) The synthesis and purification steps are similar to those in Comparative Example 1, step (6), but the types and amounts of intermediates used are different. Intermediate 7 (59.3 mg, 0.030 mmol), intermediate c (35.4 mg, 0.030 mmol), ultra-dry tetrahydrofuran (7 ml), and ultra-dry triethylamine (2 ml) were weighed into a mixed solvent. Catalytic amounts of cuprous iodide (1.5 mg, 0.0080 mmol) and tetra(triphenylphosphine)palladium (6.8 mg, 0.0059 mmol) were added for synthesis, yielding 62 mg of the black film-like product PZPDTDPPT, with a yield of 66%. GPC: Mn = 35.8 kg•mol -1 Mw = 106.6 kg•mol -1 PDI=2.97.

[0110] The donor photovoltaic material prepared in this embodiment was dissolved in a chloroform solution, and its molar concentration was (10) -5 -10 - 4 The UV-Vis absorption spectrum of the resulting chloroform solution (mol / L) is shown in the figure. Figure 4 .

[0111] The donor photovoltaic material prepared in this embodiment was spin-coated into a thin film with a thickness of approximately 70 nm. The UV-Vis absorption spectrum of the film is shown below. Figure 4 .

[0112] The donor photovoltaic material prepared in this embodiment was tested for electrochemical performance using cyclic voltammetry (CV) on an electrochemical workstation. The cyclic voltammetry curves are shown in the figure. Figure 6 .

[0113] Using porphyrin molecules as the donor material and small molecule Y6 as the acceptor material, a front-mounted device was fabricated to study its photovoltaic performance. The device structure is ITO / PEDOT:PSS / active layer / Phen-NaDPO / Ag, with a donor-acceptor mass ratio of 1:2 in the active layer. The JV curve under illumination is shown in [Figure number missing]. Figure 7 The fabricated device exhibits a photoelectric conversion efficiency of 2.50% and a short-circuit current of 11.94 mA / cm². 2 The open-circuit voltage is 0.57V and the fill factor is 36.65%.

[0114] The photoelectric conversion efficiency achieved by the heterojunction solar cell prepared in this embodiment is the highest photoelectric conversion efficiency obtained by using an active layer material prepared with an optimized donor-acceptor ratio of 1:2 and subjected to CS2 steam thermal annealing.

[0115] Using the polymer donors prepared in Example 1 and Comparative Example 1, it can be seen that the absorption of the two donor photovoltaic materials differs significantly. In solution, Comparative Example 1 exhibits four absorption peaks at 463, 571, 781, and 865 nm, respectively; while Example 1 shows a plateau-shaped absorption band and two absorption peaks at 467, 801, and 890 nm, respectively. Even in solution, both polymers still exhibit significant near-infrared absorption, indicating a substantial π-electron delocalization effect between the connecting units. In thin film, Comparative Example 1 and Example 1 exhibit significantly different optical behaviors. The absorption peaks of Comparative Example 1 in the thin film are located at 465, 583, 778, and 855 nm, respectively. Compared to solution absorption, the first two absorption peaks show a slight red shift, while the latter two show a slight blue shift. This phenomenon can be attributed to the competition and superposition of two effects: intermolecular π–π stacking and H-aggregation. The polymer chain conformation in the film is "frozen" and tends towards planarization, enhancing π-electron delocalization and effective conjugation length, thus dominating the redshift of the first two peaks. Simultaneously, the formed H-aggregates induce exciton coupling, enhancing high-energy transitions and dominating the blueshift of the latter two peaks. In contrast, the absorption peaks of Example 1 in the film are located at 474, 814, and 904 nm, all showing a redshift relative to the solution, indicating enhanced π–π stacking in the solid state, which can be mainly attributed to the optical behavior dominated by J-aggregation.

[0116] The electrochemical performance of the two polymer donors, prepared in Example 1 and Comparative Example 1 respectively, was obtained by cyclic voltammetry testing. The calculated HOMO level of Comparative Example 1 was -5.33 eV, and the LUMO level was -3.88 eV. The HOMO level of Example 1 was -5.32 eV, and the LUMO level was -3.90 eV. The energy level difference is consistent with the device voltage trend.

[0117] The efficiency comparison between the heterojunction cells prepared in Comparative Example 1 and Example 1 and Y6 shows that, compared with the DA type PZPTDPPT, the ADA type PZPDTDPPT device achieves a significant improvement of over 119% in short-circuit current density and the fill factor is also improved. Although the open-circuit voltage is slightly reduced, the final photoelectric conversion efficiency is greatly improved from 1.07% to 2.50%, an increase of 133%. This fully demonstrates the key role of the ADA structure design in improving the photovoltaic performance of this type of porphyrin-DPP polymer, especially in improving photocurrent.

[0118] Furthermore, as shown in the figure, the electron mobility of the blend film of Comparative Example 1 and Y6 is 4.70 × 10⁻⁶. -4 cm 2 V -1 s -1 The hole mobility is only 0.25×10 -5 cm 2 V -1 s -1 This indicates a severe imbalance in carrier transport. The electron mobility of the blend film in Example 1 increased to 6.79 × 10⁻⁶. -4 cm 2 V -1 s -1 Hole mobility significantly increased to 7.81 × 10⁻⁶. -5 cm 2 V -1 s -1 The μe / μh ratio decreased to 8.7, and the carrier transport balance was greatly improved. This confirms that the ADA-type structure effectively optimized the intermolecular stacking through the synergistic effect of the electron-withdrawing units on both sides of the DPP, forming a more continuous charge, especially hole transport channel, and achieving a significant increase in short-circuit current density.

[0119] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A class of ADA-type polymer photovoltaic materials based on porphyrin, characterized in that, It has the following structural formula as shown in equation (Ⅰ): （Ⅰ）， Wherein, R1 is an alkyl group with 12 to 16 carbon atoms; R2 is an alkyl group with 8 to 16 carbon atoms, and n is 7 to 13.

2. The ADA-type polymer photovoltaic material based on porphyrin according to claim 1, characterized in that, R1 is at least one of 2-hexyldecyl and n-hexadecyl; And / or, R2 is at least one of 2-ethylhexyl and n-octyl.

3. A method for preparing a type of ADA-type polymer photovoltaic material based on porphyrin as described in any one of claims 1 to 2, characterized in that, Includes the following steps: (1) Dissolve 3,4,5-trihydroxybenzaldehyde and alkyl bromide in an organic solvent and react at 60-70°C for 12-24 hours under the action of a catalyst to obtain compound (II); （Ⅱ）； (2) Compound (II) and dipyrrolemethane were dissolved in an organic solvent, and trifluoroacetic acid was added under light-protected conditions. The reaction was carried out at room temperature for 10 to 16 hours. Then 2,3-dichloro-5,6-dicyanobenzoquinone was added, and the reaction was continued for 0.5 to 3 hours to obtain compound (III). （Ⅲ）， （Ⅳ）； (3) Dissolve compound (Ⅲ) in an organic solvent, add N-bromosuccinimide at low temperature and react for 0.3 to 0.7 hours, then continue the reaction at room temperature for 0.5 to 5 hours to obtain compound (Ⅳ); (4) Dissolve compound (Ⅳ) in an organic solvent, add zinc acetate, react at 40-60°C for 0.5-2 hours, and then react at room temperature for 12-24 hours to obtain compound (Ⅴ). （Ⅴ）， （Ⅵ）； (5) Dissolve compound (V) in an organic solvent, add trimethylsilyl acetylene, and react at 60-100°C for 12-48 hours under the action of a catalyst to obtain compound (VI). (6) Dissolve the monobromine-containing pyrrolopyrrole dione derivative and pinacol diboronic acid in an organic solvent and react at 60-100°C for 48-72 hours under the action of a catalyst to obtain compound (VII). （Ⅶ）； (7) Dissolve compound (VII) in an organic solvent, add N-bromosuccinimide at low temperature and react for 0.5 to 3 hours to obtain compound (VIII). （Ⅷ）； (8) Dissolve compound (VI) in an organic solvent, add tetrabutylammonium fluoride solution at room temperature, stir for 5 to 30 minutes, quench with water to stop the reaction, extract, and evaporate to dryness to obtain compound (IX). （Ⅸ）； (9) Dissolve compounds (IX) and (VIII) in an organic solvent and heat under reflux for 48–72 hours in the presence of a catalyst to obtain the target ADA-type polymer; Wherein, the definitions of R1 and R2 are the same as those in the ADA-type polymer photovoltaic material structure based on porphyrin described in any one of claims 1 to 2.

4. The preparation method according to claim 3, characterized in that, The organic solvent mentioned in step (1) is N,N-dimethylformamide; And / or, the ratio of 3,4,5-trihydroxybenzaldehyde to organic solvent in step (1) is 1 mmol: 3-8 ml; And / or, the molar ratio of 3,4,5-trihydroxybenzaldehyde and alkyl bromide in step (1) is 1:3 to 1:5; And / or, the catalyst in step (1) is anhydrous potassium carbonate and potassium iodide; the molar amount of anhydrous potassium carbonate is 2 to 4 times the molar amount of 3,4,5-trihydroxybenzaldehyde; the molar amount of potassium iodide is 0.05 to 0.2 times the molar amount of 3,4,5-trihydroxybenzaldehyde; And / or, the organic solvent mentioned in step (2) is one of chloroform and dichloromethane; And / or, the ratio of compound (II) and organic solvent in step (2) is 1 mmol: 60-120 ml; And / or, the molar ratio of compound (II) and dipyrrolemethane in step (2) is 1:1 to 1:2; And / or, the molar amount of trifluoroacetic acid in step (2) is 0.2 to 0.6 times that of compound (II); And / or, the molar amount of 2,3-dichloro-5,6-dicyanobenzoquinone in step (2) is 1.5 to 2.0 times that of compound (II).

5. The preparation method according to claim 3, characterized in that, The organic solvent mentioned in step (3) is at least one of chloroform and dichloromethane; And / or, the ratio of compound (III) and organic solvent in step (3) is 1 mmol: 400-800 ml; And / or, the molar ratio of compound (III) in step (3) to N-bromosuccinimide is 1:2 to 1:4; And / or, the low temperature mentioned in step (3) should be controlled between -10 and 0°C; And / or, the organic solvent mentioned in step (4) is a mixture of at least one of chloroform and dichloromethane with methanol; the molar amount of at least one of chloroform and dichloromethane is 500 to 3000 times the molar amount of compound (IV), and the volume ratio of at least one of chloroform and dichloromethane to methanol is 6:1 to 3:

1. And / or, the molar ratio of compound (Ⅳ) to zinc acetate in step (4) is 1:2 to 1:

10.

6. The preparation method according to claim 3, characterized in that, The organic solvent mentioned in step (5) is a mixed solvent of tetrahydrofuran and triethylamine; the molar amount of tetrahydrofuran is 500 to 2000 times the molar amount of compound (V), and the volume ratio of tetrahydrofuran to triethylamine is 2:1 to 5:

1. And / or, the molar ratio of compound (V) to trimethylsilylacetylene in step (5) is 1:4 to 1:6; And / or, the catalyst described in step (5) is bis(triphenylphosphine)palladium dichloride and cuprous iodide; the molar amounts of both are 0.05 to 0.2 times the molar amount of compound (V); And / or, the molar ratio of the monobrominated pyrrolopyrrole dione derivative and pinacol diboronic acid ester described in step (6) is 1:0.8 to 1:1; And / or, the organic solvent in step (6) is tetrahydrofuran, and the molar amount is 200 to 500 times the molar amount of the pyrrolopyrrole dione derivative with monobromine; And / or, the catalyst in step (6) is anhydrous potassium carbonate and tetra(triphenylphosphine)palladium; the molar amount of anhydrous potassium carbonate is 3 to 5 times the molar amount of the monobrominated pyrrolopyrrole dione derivative, and the molar amount of tetra(triphenylphosphine)palladium is 0.01 to 0.1 times the molar amount of the monobrominated pyrrolopyrrole dione derivative.

7. The preparation method according to claim 3, characterized in that, The organic solvent mentioned in step (7) is chloroform; And / or, the ratio of (VII) to organic solvent in step (7) is 1 mmol: 500-600 ml; And / or, the molar ratio of compound (VII) in step (7) to N-bromosuccinimide is 1:2 to 1:2.5; And / or, the low temperature mentioned in step (7) should be controlled between -10 and 0°C.

8. The preparation method according to claim 3, characterized in that, The organic solvent mentioned in step (8) is tetrahydrofuran; the molar amount of tetrahydrofuran is 2000 to 4000 times the molar amount of compound (VI); And / or, the molar ratio of compound (VI) in step (8) to tetrabutylammonium fluoride is 1:3 to 1:5; And / or, the concentration of the tetrabutylammonium fluoride solution in step (8) is 0.5 to 1.5 mol / L, and the solvent is tetrahydrofuran.

9. The preparation method according to claim 3, characterized in that, The molar ratio of compound (IX) and compound (VIII) in step (9) is 1:1 to 1:2; And / or, the organic solvent in step (9) is a mixed solvent of tetrahydrofuran and triethylamine; the molar amount of tetrahydrofuran is 2000 to 3000 times the molar amount of compound (IX), and the volume ratio of tetrahydrofuran to triethylamine is 2:1 to 5:1; And / or, the catalyst described in step (9) is tetra(triphenylphosphine)palladium and cuprous iodide; the molar amount of tetra(triphenylphosphine)palladium is 0.1 to 0.5 times the molar amount of compound (IX); the molar amount of cuprous iodide is 0.25 to 0.3 times the molar amount of compound (IX); And / or, the temperature of the heating reflux in step (9) is 60 to 80°C.

10. The application of the porphyrin-based ADA-type polymer photovoltaic material as described in any one of claims 1 to 2 as an electron donor material for the preparation of the active layer of an organic solar cell.

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