Ternary copolymer donor material as well as preparation method and application thereof

Abstract

The invention provides a terpolymer donor material and a preparation method and application thereof.The terpolymer donor material comprises a D-A alternating copolymer and a third unit introduced into the D-A alternating copolymer, and the third unit contains a thiazolobenzothiophene group or a benzodithiazole group; according to the ternary polymerization donor material, a thiazolobenzothiophene group or a benzodithiazole structure is introduced into a main chain of a polymer donor to prepare a series of novel polymer donor materials, and the unique micro D-A charge transfer characteristic of the novel polymer donor material effectively optimizes polymer electron delocalization distribution, promotes intramolecular charge transfer and improves the carrier mobility of the material.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic technology, specifically to a ternary copolymer donor material, its preparation method, and its application. Background Technology

[0002] Organic solar cells (OSCs), as a novel photovoltaic technology, possess advantages such as lightweight, flexibility, and large-area fabrication via solution methods, making them an important technology for green and clean energy utilization with broad application prospects. With the synthesis of new materials, especially the emergence of non-fullerene acceptor small molecules and the continuous optimization of device processes, the power conversion efficiency (PCE) of single-junction OSCs has reached over 20%. Compared to the rapid development of non-fullerene acceptor small molecules, the development of donor polymers has been relatively slow. To date, only a few polymer donors (such as PM6, D18, PBQx-TF, etc.) have achieved high efficiency in binary devices. Therefore, developing high-performance donor polymers suitable for non-fullerene systems is an important direction for further improving the efficiency of OSCs. In typical DA conjugated polymers, polymer units (D and A parts) are alternately connected along the polymer backbone. However, due to the limitation of the delocalization of charge transfer in a small electron cloud between the two DA monomers, intramolecular charge transfer is suppressed, resulting in low carrier mobility, ineffective absorption spectrum expansion, and limitation of short-circuit current. J SC ) and open circuit voltage ( V OC Further improvements in [the technology] ultimately led to stagnation in PCE. Therefore, existing technologies require further development. Summary of the Invention

[0003] To address the shortcomings of existing technologies and solve the aforementioned problems, a ternary copolymer donor material, its preparation method, and its applications are proposed, and the following technical solution is provided: A ternary copolymer donor material comprising an alternating DA copolymer and a third unit introduced into the alternating DA copolymer, wherein the third unit contains a thiazobenzothiophene group or a benzodithiazole group.

[0004] Furthermore, the general structural formula of the third unit is shown in Formula I: Formula I Where R1 is C or N; R2 is hydrogen, Cl-C 20 Straight-chain alkyl or branched alkyl, C1-C 20 Straight-chain alkoxy or branched-chain alkoxy, C1-C 20 Straight-chain silane or branched-chain silane, C1-C 20Straight-chain alkylthio or branched-chain alkylthio; R3 is a halogen or hydrogen.

[0005] Furthermore, the third unit is or .

[0006] Furthermore, the alternating DA copolymer comprises electron donor units D and electron acceptor units A, and the general structural formula of the ternary copolymer donor material is shown in Formula II: Formula II Where m is 0.5-0.95 and n is 0.05-0.5.

[0007] Furthermore, the electron donor unit D is one of the following structural units: , , , , , , , , , , , ; The electron acceptor unit A is one of the following structural units: , , , , , , ; Wherein, R11 is hydrogen, C1-C 20 Straight-chain alkyl or branched alkyl, C1-C 20 Straight-chain alkoxy or branched-chain alkoxy, C1-C 20 Straight-chain silane or branched-chain silane, C1-C 20 Straight-chain alkylthio or branched-chain alkylthio; R21 is hydrogen or halogen.

[0008] Furthermore, the structural formula of the ternary copolymer donor material is as follows: , , or , where X is a halogen element.

[0009] In addition, the present invention also provides a method for preparing the above-mentioned ternary copolymer donor material, the method comprising: introducing a third unit containing a thiazobenzothiophene group or a benzodithiazole group into an alternating DA copolymer to copolymerize and generate a ternary copolymer thiazobenzothiophene-based ternary copolymer donor material.

[0010] Furthermore, the electron donor unit D, electron acceptor unit A, and third unit of the DA alternating copolymer, along with the palladium-based catalyst, were added to anhydrous toluene solvent to obtain a mixture. The mixture was stirred at 110-120°C for 22-26 hours, then poured into water, extracted with dichloromethane, and dried on anhydrous sodium sulfate.

[0011] Furthermore, the molar ratio of the electron donor unit D, the electron acceptor unit A, and the third unit is 1:0.5-0.95:0.05-0.5, and the palladium-based catalyst is tetrakis(triphenylphosphine)palladium (Pd(PPh3)4). Before the electron donor unit D, the electron acceptor unit A, and the third unit of the DA alternating copolymer, as well as the palladium-based catalyst, are added to the anhydrous toluene solvent, the anhydrous toluene solvent is deoxygenated with an inert gas for 30 minutes.

[0012] The present invention also provides the application of ternary copolymer donor materials in organic solar cells, wherein the ternary copolymer donor materials are applied in the photoactive layer of organic solar cells.

[0013] Beneficial effects: 1. This invention introduces thiazobenzothiophene groups or benzodithiazole groups into the polymer donor. Through their unique micro-DA charge transfer characteristics, the electron delocalization distribution of the polymer is effectively optimized, the energy level of the polymer is significantly adjusted, and the resulting terpolymer has good charge transport capability, which is beneficial to obtaining superior photoelectric properties.

[0014] 2. The third component of this invention works synergistically with electron donor unit D and electron acceptor unit A, acting as a bridge for intramolecular charge transport. The molecular conformation of the dipole moment is more balanced, promoting the generation of a wider electron cloud delocalization, enhancing the intramolecular charge transfer effect, broadening the absorption spectrum, and increasing the carrier mobility of the active layer. The resulting ternary random copolymer material has a spectrum and energy level within the common application range, and can be combined with various types of donor and acceptor materials for complementarity.

[0015] 3. The present invention employs a ternary random copolymerization polymerization method, which can synergistically obtain good crystallinity and donor-acceptor compatibility in the binary system, and obtain good fibrous phase separation. This is beneficial for obtaining smaller composites to achieve high device performance. Attached Figure Description

[0016] Figure 1This is the ultraviolet absorption spectrum of the polymer donor material WD1 synthesized in Example 1 of the present invention in a thin film.

[0017] Figure 2 This is the fluorescence spectrum of the polymer donor material WD1 synthesized in Example 1 of the present invention in a thin film.

[0018] Figure 3 This is the 1H NMR spectrum of compound 6 synthesized in Example 1 of this invention.

[0019] Figure 4 This is a DSC diagram of the polymer donor WD1 synthesized in Example 1 of the present invention.

[0020] Figure 5 This is a schematic diagram of the structure of the organic solar cell of the present invention. In the figure, 1 is a transparent conductive substrate, 2 is an anode modification layer, 3 is an organic active layer, 4 is a cathode modification layer, and 5 is a metal electrode.

[0021] Figure 6 The current-voltage (JV) curves are shown for the ternary organic solar cell in Experimental Example 1 and Comparative Example 1. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application.

[0023] According to embodiments of the present invention, a ternary copolymer donor material is provided, comprising an alternating DA copolymer and a third unit introduced into the alternating DA copolymer. The third unit contains a thiazobenzothiophene group or a benzodithiazole group. The ternary copolymer donor material introduces the thiazobenzothiophene group or benzodithiazole structure into the main chain of the polymer donor, thus preparing a series of novel polymer donor materials. Its unique micro-DA charge transfer characteristics effectively optimize the delocalization distribution of polymer electrons, promote intramolecular charge transfer, and improve the carrier mobility of the material. At the same time, the ternary copolymerization method effectively improves crystallinity and compatibility with the host system, forming excellent phase separation morphology, reducing the static disorder of charge transfer states at the D / A interface and the non-radiative energy loss of the device. It can be used as a third component to achieve high energy conversion efficiency in organic photovoltaic systems.

[0024] The experimental materials and reagents used in the following experimental examples can all be obtained commercially or through known experimental methods.

[0025] Example 1 Preparation method of ternary copolymer donor WD1 material (1) Under nitrogen protection, 4,6-dibromo-1,3-bis(tert-butoxycarbonyl)sthiazole (1.0 eq, 10.0 mmol), 2-bromo-5-(trimethyltinyl)thiophene derivative (1.0 eq, 10.0 mmol), and tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) (5 mol%, 0.5 mmol) were added to a dry Schlenk reaction flask, followed by the injection of anhydrous DMF (100 mL, concentration 0.1 mol / L). After three purging cycles of vacuum and nitrogen, the system was refluxed in an oil bath at 110 °C for 36 h with stirring. The reaction mixture was monitored by petroleum ether / ethyl acetate = 10:1 (TLC) until the starting material was completely converted. After cooling to room temperature, the reaction mixture was slowly poured into ice water (500 mL) and extracted with dichloromethane (3 × 50 mL). The organic phases were combined, washed with saturated sodium chloride solution (2 × 50 mL), dried over anhydrous sodium sulfate for 30 min, filtered, and the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 15:1), the target fraction was collected, the solvent was removed by vacuum distillation, and the product was dried under vacuum for 24 h to give compound 1, with a yield of 72%. NMR data for product 1:¹H NMR (400 MHz, CDCl₃) δ 1.52 (s, 18H), 7.32 (d, J = 3.6 Hz, 1H), 7.45 (d, J = 3.6 Hz, 1H), 7.68 (s, 1H). (2) Under nitrogen protection, compound 1 (1.0 eq, 5.0 mmol), Pd(OAc)2 (3 mol%, 0.15 mmol), PCy3·BF4 (6 mol%, 0.3 mmol), and Cs2CO3 (2.5 eq, 12.5 mmol) were added to a dry Schlenk flask, followed by the injection of anhydrous DME (50 mL, 0.1 mol / L). After three purging cycles of vacuum and nitrogen, the system was stirred in a 90°C oil bath for 18 h. TLC (petroleum ether / ethyl acetate = 8:1) was used to monitor the reaction until the starting material was completely converted. The mixture was cooled to room temperature, filtered through diatomaceous earth to remove insoluble salts, and the filtrate was extracted with ethyl acetate (3 × 30 mL). The organic phases were combined, washed with saturated sodium chloride solution (2 × 30 mL), dried over anhydrous sodium sulfate for 30 min, filtered, and the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 10:1). The target fraction was collected, the solvent was removed by vacuum evaporation, and the product was dried under vacuum for 24 h to give compound 2, with a yield of 68%. NMR data for product 2: ¹H NMR (400 MHz, CDCl₃) δ 1.50 (s, 18H), 7.28 (d, J = 3.6 Hz, 1H), 7.42 (d, J = 3.6 Hz, 1H), 7.65 (s, 1H).(3) Compound 2 (1.0 eq, 3.0 mmol) was dissolved in anhydrous chloroform (20 mL, 0.15 mol / L), transferred to a dry round-bottom flask, cooled to 0°C in an ice bath, and wrapped with aluminum foil to protect from light. NBS (1.2 eq, 3.6 mmol, added in three portions, 10 min apart) was added in portions, and the mixture was stirred at 0°C for 3 h. TLC (petroleum ether / ethyl acetate = 12:1) was used to monitor the complete conversion of the starting material. The precipitated succinimide solid was removed by filtration, and the filtrate was washed successively with saturated sodium bicarbonate solution (20 mL) and deionized water (2 × 20 mL). The organic phase was dried over anhydrous sodium sulfate for 30 min, filtered, and the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 15:1), the target fraction was collected, the solvent was removed by vacuum distillation, and the product was dried under vacuum for 24 h to obtain compound 3, with a yield of 75%. NMR data of product 3: ¹H NMR (400 MHz, CDCl3) δ 1.51 (s, 18H), 7.30 (s, 1H), 7.66 (s, 1H). (4) Under nitrogen protection, compound 3 (1.0 eq, 2.0 mmol), 2-ethylhexyl-5-(trimethyltinyl)thiophene (2.3 eq, 4.6 mmol), and Pd(PPh3)4 (8 mol%, 0.16 mmol) were added to a dry Schlenk flask, and anhydrous DMF (20 mL, concentration 0.1 mol / L) was injected. After the system was purged with vacuum and nitrogen three times, it was stirred and refluxed in an oil bath at 115 °C for 48 h. TLC (petroleum ether / ethyl acetate = 5:1) was used to monitor the complete conversion of the starting material. After cooling to room temperature, the reaction solution was poured into ice water (100 mL) and extracted with dichloromethane (3 × 20 mL). The organic phases were combined, washed with saturated sodium chloride solution (2 × 20 mL), dried over anhydrous sodium sulfate for 30 min, filtered, and the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 8:1), the target fraction was collected, the solvent was removed by vacuum distillation, and the product was dried under vacuum for 24 h to give compound 4, with a yield of 70%. The NMR data of product 4 are as follows: ¹H NMR (400 MHz, CDCl₃) δ 0.87–0.93 (m, 12H), 1.25–1.45 (m, 16H), 1.50 (s, 18H), 2.80 (d, J = 7.2 Hz, 4H), 6.98 (d, J = 3.6 Hz, 2H), 7.12 (d, J = 3.6 Hz, 2H), 7.62 (s, 1H). (5) Dissolve compound 4 (1.0 eq, 1.0 mmol) in dichloromethane (10 mL, concentration 0.1 mol / L), transfer to a round-bottom flask, and stir at room temperature.Concentrated hydrochloric acid (5.0 eq, 5.0 mmol, 1 mL / min) was slowly added dropwise, and the reaction was stirred at room temperature for 6 h. TLC (petroleum ether / ethyl acetate = 3:1) was monitored until the Boc protecting group was completely removed. After the reaction was complete, saturated sodium bicarbonate solution was slowly added to neutralize to pH 7-8. The mixture was separated, and the aqueous phase was extracted with dichloromethane (2 × 10 mL). The combined organic phases were washed with saturated sodium chloride solution (2 × 10 mL), dried over anhydrous sodium sulfate for 30 min, filtered, and the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 5:1). The target fraction was collected, the solvent was removed by vacuum distillation, and the product was dried under vacuum for 24 h to give compound 5, in 85% yield. NMR data of product 5:¹H NMR (400 MHz, CDCl3) δ 0.87-0.93 (m, 12H), 1.25-1.45 (m, 16H), 2.80 (d, J=7.2 Hz, 4H), 6.98 (d, J=3.6 Hz, 2H), 7.12 (d, J=3.6 Hz, 2H), 7.58 (s, 1H), 8.21 (s, 1H). (5) Compound 5 (1.0 eq, 0.5 mmol) was dissolved in anhydrous chloroform (3.3 mL, concentration 0.15 mol / L), transferred to a dry round-bottom flask, cooled to 0°C in an ice bath, and wrapped with aluminum foil to protect from light. NBS (2.3 eq, 1.15 mmol, added in four portions, 10 min apart) was added in batches, and the reaction was stirred at 0 °C for 5 h. TLC (petroleum ether / ethyl acetate = 10:1) was monitored until complete conversion to the dibromo derivative. The precipitated succinimide solid was removed by filtration, and the filtrate was washed successively with saturated sodium bicarbonate solution (10 mL) and deionized water (2 × 10 mL). The organic phase was dried over anhydrous sodium sulfate for 30 min, filtered, and the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 12:1), the target fraction was collected, the solvent was removed by vacuum distillation, and the product was dried under vacuum for 24 h to give compound 6, with a yield of 78%. The 1H NMR spectrum of product 6 is shown below. Figure 3As shown, the NMR data are: ¹H NMR (400 MHz, CDCl3) δ 0.87–0.93 (m, 12H), 1.25–1.45 (m, 16H), 2.80 (d, J=7.2 Hz, 4H), 7.00 (s, 2H), 7.55 (s, 1H), 8.18 (s, 1H). (7) Under nitrogen protection, compound 6 (0.1 eq, 0.02 mmol), bis(trimethyltin)-BDT donor monomer (1 eq, 0.2 mmol), thienopyrrole dione (TPD) acceptor monomer (0.8 eq, 0.16 mmol), benzodithiazole acceptor unit (0.1 eq, 0.02 mmol), Pd2(dba)3 (2.5 mol%, 0.005 mmol), and P(o-Tol)3 (10 mol%, 0.02 mmol) were precisely added to a dry Schlenk flask, followed by the injection of anhydrous toluene (4 mL, concentration 0.05 mol / L). After three purging cycles of vacuum and nitrogen, the system was placed in a 120°C oil bath and stirred for polymerization for 60 h, with GPC monitoring performed every 12 h. After polymerization, the mixture was cooled to room temperature, and the reaction solution was slowly added dropwise to vigorously stirred methanol (40 mL) to precipitate the polymer. The crude polymer was collected by filtration and extracted sequentially with methanol, acetone, and n-hexane using a Soxhlet extractor for 24 h each, followed by a Soxhlet extract with chloroform for 24 h. The chloroform-dissolved fraction was collected, the solvent was removed by vacuum evaporation, and the product was dried under vacuum for 48 h to obtain the purified conjugated polymer 7, WD1, with a yield of 82%. GPC (THF, vs. PS): Mn = 32.5 kDa, PDI = 1.87. ¹H NMR (400 MHz, CDCl3) δ 0.85–0.95 (m, 36H), 1.20–1.50 (m, 48H), 2.75–2.85 (m, 12H), 6.95–7.10 (m, 6H), 7.50–7.65 (m, 3H), 8.15–8.25 (m, 1H). The UV spectrum of WD1 is as follows. Figure 1 As shown, the fluorescence spectrum is as follows Figure 2 As shown, the DSC diagram is as follows Figure 4 As shown.

[0026] Example 2 Preparation method of ternary copolymer donor material WD2 Under nitrogen protection, the following monomers were precisely added to a dry Schlenk flask: bis(trimethyltin)-BDT donor monomer (1 eq, 0.2 mmol), thienopyrrole dione (TPD) acceptor monomer (0.8 eq, 0.16 mmol), benzodithiazole acceptor unit (0.2 eq, 0.04 mmol), Pd2(dba)3 (2.5 mol%, 0.005 mmol), and P(o-Tol)3 (10 mol%, 0.02 mmol). Anhydrous toluene (4 mL, 0.05 mol / L) was then injected. After three purging cycles of vacuum and nitrogen, the system was stirred and polymerized in a 120°C oil bath for 60 h, with GPC monitoring performed every 12 h. After polymerization, the mixture was cooled to room temperature, and the reaction solution was slowly added dropwise to vigorously stirred methanol (40 mL), precipitating the polymer. The crude polymer was collected by filtration and extracted sequentially with methanol, acetone, and n-hexane using a Soxhlet extractor for 24 h each, followed by a final Soxhlet extract with chloroform for 24 h. The chloroform-dissolved fraction was collected, the solvent was removed by vacuum evaporation, and the product was dried under vacuum for 48 h to obtain the purified conjugated polymer WD2, with a yield of 88%. GPC (THF, vs. PS): Mn = 37.2 kDa, PDI = 1.59.

[0027] Example 3 Preparation method of ternary copolymer donor material WD3 Under nitrogen protection, compound 6 (0.3 eq, 0.06 mmol), bis(trimethyltin)-BDT donor monomer (1 eq, 0.2 mmol), thienopyrrole dione (TPD) acceptor monomer (0.6 eq, 0.12 mmol), benzodithiazole acceptor unit (0.1 eq, 0.02 mmol), Pd2(dba)3 (2.5 mol%, 0.005 mmol), and P(o-Tol)3 (10 mol%, 0.02 mmol) were precisely added to a dry Schlenk flask. Anhydrous toluene (4 mL, 0.05 mol / L) was then injected. After three purging cycles of vacuum and nitrogen, the system was stirred and polymerized in a 120°C oil bath for 60 h, with GPC monitoring performed every 12 h. After polymerization, the mixture was cooled to room temperature, and the reaction solution was slowly added dropwise to vigorously stirred methanol (40 mL), precipitating the polymer. The crude polymer was collected by filtration and extracted sequentially with methanol, acetone, and n-hexane using a Soxhlet extractor for 24 h each, followed by a final Soxhlet extract with chloroform for 24 h. The chloroform-dissolved fraction was collected, the solvent was removed by vacuum evaporation, and the product was dried under vacuum for 48 h to obtain the purified conjugated polymer WD3, with a yield of 79%. GPC (THF, vs. PS): Mn = 29.5 kDa, PDI = 1.36.

[0028] The structure of organic solar cells is as follows Figure 5 As shown, 1 is a transparent conductive substrate, 2 is an anode modification layer, 3 is an organic active layer, 4 is a cathode modification layer, and 5 is a metal electrode. The aforementioned ternary copolymer donor material was applied to the photoactive layer for testing. The ternary copolymer donor material was introduced into the binary host system of organic solar cells as a third component to construct ternary organic solar cells.

[0029] Experimental Example 1: Fabrication of a ternary organic solar cell based on WD1, the donor material of Example 1 A PEDOT:PSS solution was spin-coated onto a cleaned conductive (indium tin oxide, ITO) glass substrate and heated at 150°C for 15 minutes, resulting in a PEDOT:PSS thickness of 30 nm. The polymer donor material WD1 obtained in Example 1 was added as a third component to the main system polymer donor PM6 and non-fullerene acceptor material L8BO at a weight ratio of 0.2:1:1.4 dissolved in chloroform. Based on the solution concentration of donor material PM6 being 6.5 mg / mL, this solution was spin-coated onto the PEDOT:PSS film as an active layer with a thickness of 100 nm. A PDINN solution was then spin-coated onto the active layer, and Ag was deposited onto the PDINN surface to a thickness of 80 nm, thus obtaining the organic solar cell (see [link to documentation]). Figure 5 PEDOT:PSS is an aqueous solution of a polymer composed of two substances: PEDOT and PSS. PEDOT is a polymer of EDOT (3,4-ethylenedioxythiophene monomer), and PSS is polystyrene sulfonate. PEDOT:PSS serves as the anode of an organic solar cell. PDINN is an abbreviation for N,N'-bis{3-[3-(dimethylamino)propylamino]propyl}piperene-3,4,9,10-tetracarboxylic acid diimide, which serves as the electron transport layer.

[0030] Experimental Example 2: Fabrication of a ternary organic solar cell based on WD2, the donor material of Example 2 Unlike Experimental Example 1, the polymer donor material WD2 obtained in Example 2 was added as a third component to the main system polymer donor PM6 and non-fullerene acceptor material L8BO in a weight ratio of 0.2:1:1.4 dissolved in chloroform, and other conditions were the same as in Experimental Example 1.

[0031] Experimental Example 3: Preparation of ternary organic solar cells based on WD3, the donor material of Example 3 Unlike Experimental Example 1, the polymer donor material WD3 obtained in Example 3 was added as the third component to the main system polymer donor PM6 and non-fullerene acceptor material L8BO in a weight ratio of 0.2:1:1.4 dissolved in chloroform, and other conditions were the same as in Experimental Example 1.

[0032] Comparative Example 1 Fabrication of binary organic solar cells based on PM6:L8BO A PEDOT:PSS solution was spin-coated onto a cleaned conductive (indium tin oxide, ITO) glass substrate and heated at 150°C for 15 minutes, resulting in a PEDOT:PSS thickness of 30 nm. The polymer donor PM6 and the non-fullerene acceptor L8BO were dissolved in chloroform at a weight ratio of 1:1.2, with a PM6 concentration of 6.8 mg / mL. This solution was spin-coated onto the PEDOT:PSS film as an active layer with a thickness of 100 nm. A PDINN solution was then spin-coated onto the active layer, and Ag was deposited onto the PDINN surface to a thickness of 80 nm, thus obtaining the organic solar cell. PEDOT:PSS is an aqueous solution of a polymer, composed of two substances: PEDOT and PSS. PEDOT is a polymer of EDOT (3,4-ethylenedioxythiophene monomer), and PSS is polystyrene sulfonate. PEDOT:PSS serves as the anode of the organic solar cell in this embodiment. PDINN is an abbreviation for N,N'-bis{3-[3-(dimethylamino)propylamino]propyl}piperene-3,4,9,10-tetracarboxylic acid diimide, which serves as the electron transport layer.

[0033] The photovoltaic performance of the polymers assembled in Experimental Examples 1-3 and Comparative Example 1 was characterized using a Keithley 2400 SourceMeter and a Xenon-lamp-based solar simulator, respectively. The performance was achieved at AM 1.5G 100mW / cm². 2 Under light intensity, the open-circuit voltage of the ternary solar cell device based on WD1 as the third component in Experimental Example 1 was 0.925 V, and the short-circuit current density was 26.89 mA / cm². 2 The fill factor is 79.07%, and the power conversion efficiency is 19.67%. In Experiment 2, the open-circuit voltage of the ternary solar cell device based on WD2 as the third component is 0.926 V, and the short-circuit current density is 26.21 mA / cm². 2 The fill factor is 77.32%, and the power conversion efficiency is 18.76%. In Experiment 3, the open-circuit voltage of the ternary solar cell device based on WD3 as the third component is 0.922 V, and the short-circuit current density is 26.35 mA / cm². 2The fill factor is 77.93%, and the power conversion efficiency is 18.93%. In Comparative Example 1, the open-circuit voltage of the PM6:L8BO binary solar cell device is 0.908V, and the short-circuit current density is 25.17 mA / cm². 2 The fill factor is 76.32%, and the power conversion efficiency is 17.44%. The current-voltage (JV) curves of the solar cells of the corresponding devices in Example 1 and Comparative Example 1 are shown below. Figure 6 Show.

[0034] As can be seen from the experimental examples and comparative examples, introducing electron-withdrawing groups as a third component into the polymer backbone, in conjunction with the existing D and A groups, lowers the overall electrostatic potential, obtains a deeper highest occupied molecular orbital (HOMO) energy level, and achieves low voltage loss. V loss ), and achieved high V OC Through a rational random copolymerization strategy, the chemical and physical properties of polymer materials can be greatly optimized. By introducing a third component mainly composed of thiazobenzothiophene, where thiazophene is an electron-withdrawing component and thiazophene is an electron-donating component, a micro-DA charge transfer channel is formed at the independent group level. This channel works synergistically with the electron donor unit D and the electron acceptor unit A, acting as a bridge for intramolecular charge transport. The molecular conformation with a more balanced dipole moment promotes the generation of a wider electron cloud delocalization, enhances the intramolecular charge transfer effect, broadens the absorption spectrum, and increases the carrier mobility of the active layer. This application creatively introduces a ternary copolymerized polymer donor material as a third component into the binary host system of organic solar cells to construct ternary organic solar cells, resulting in organic solar cells with excellent photoelectric performance.

[0035] Furthermore, as can be seen from Examples 1-3, by rationally adjusting the content of the thiazobenzothiophene component and leveraging the unique electronic properties of its nitrogen atoms, strong van der Waals forces can be formed with intramolecular D and A groups, while strong π-π interactions can also be formed with non-fullerene acceptors. This optimizes the donor-acceptor blending characteristics of the active layer and improves the crystallinity of the active layer. This not only increases carrier mobility but also reduces charge recombination. When a ternary copolymer donor material is simultaneously supplemented with a third unit containing both thiazobenzothiophene and benzodithiazole groups, compared to a polymer containing only benzodithiazole groups, the two units work synergistically. Leveraging the characteristics of ternary copolymerization and working together with the alternating D and A copolymers, the polymer's electron delocalization is optimized, its crystallinity is enhanced, exciton dissociation rate and charge transport efficiency are increased, forming an excellent phase-separated active layer structure, and ultimately further improving energy conversion efficiency.

[0036] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A ternary copolymer donor material, characterized in that, The ternary copolymer donor material includes an alternating DA copolymer and a third unit introduced into the alternating DA copolymer, the third unit containing a thiazobenzothiophene group or a benzodithiazole group.

2. The ternary copolymer donor material according to claim 1, characterized in that, The general structural formula of the third unit is shown in Equation I: Formula I Where R1 is C or N; R2 is hydrogen, Cl-C 20 Straight-chain alkyl or branched alkyl, C1-C 20 Straight-chain alkoxy or branched-chain alkoxy, C1-C 20 Straight-chain silane or branched-chain silane, C1-C 20 Straight-chain alkylthio or branched-chain alkylthio; R3 is a halogen or hydrogen.

3. The ternary copolymer donor material according to claim 2, characterized in that, The third unit is or .

4. The ternary copolymer donor material according to claim 1, characterized in that, The alternating DA copolymer comprises electron donor units D and electron acceptor units A, and the general structural formula of the ternary copolymer donor material is shown in Formula II: Formula II Where m is 0.5-0.95 and n is 0.05-0.

5.

5. The ternary copolymer donor material according to claim 4, characterized in that, The electron donor unit D is one of the following structural units: , , , , , , , , , , , ; The electron acceptor unit A is one of the following structural units: , , , , , , ; Wherein, R11 is hydrogen, C1-C 20 Straight-chain alkyl or branched alkyl, C1-C 20 Straight-chain alkoxy or branched-chain alkoxy, C1-C 20 Straight-chain silane or branched-chain silane, C1-C 20 Straight-chain alkylthio or branched-chain alkylthio; R21 is hydrogen or halogen.

6. The ternary copolymer donor material according to claim 1, characterized in that, The structural formula of the ternary copolymer donor material is: , , or , where X is a halogen element.

7. A method for preparing a ternary copolymer donor material according to any one of claims 1-6, characterized in that, The preparation method includes: introducing a third unit containing a thiazobenzothiophene group or a benzodithiazole group into an alternating DA copolymer to generate a ternary copolymer donor material.

8. The method for preparing the ternary copolymer donor material according to claim 7, characterized in that, The electron donor unit D, electron acceptor unit A, and third unit of the DA alternating copolymer, along with the palladium-based catalyst, were added to anhydrous toluene solvent to obtain a mixture. The mixture was stirred at 110-120°C for 22-26 hours, then poured into water, extracted with dichloromethane, and dried on anhydrous sodium sulfate.

9. The method for preparing the ternary copolymer donor material according to claim 8, characterized in that, The molar ratio of electron donor unit D, electron acceptor unit A, and third unit is 1:0.5-0.95:0.05-0.

5. The palladium-based catalyst is tetrakis(triphenylphosphine)palladium (Pd(PPh3)4). Before adding the electron donor unit D, electron acceptor unit A, and third unit of the DA alternating copolymer, as well as the palladium-based catalyst, to the anhydrous toluene solvent, the anhydrous toluene solvent is deoxygenated with an inert gas for 30 minutes.

10. The application of the ternary copolymer donor material according to any one of claims 1-6 in organic solar cells, characterized in that, The ternary copolymer donor material is used as the photoactive layer of organic solar cells.

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