Asymmetric benzo dithiophene diketone compounds, preparation of electron donor polymers thereof and use thereof

Abstract

The application discloses asymmetric benzo dithiophene diketone compounds and polymer materials containing asymmetric benzo dithiophene diketone units prepared by using the compounds. The materials have high green synthesis degree and green solvent processing potential, so that more material selection and processing methods are provided for the application of the materials in optoelectronic devices. In addition, the polymer material containing the asymmetric benzo dithiophene diketone unit has high photoelectric conversion efficiency in a photovoltaic device, and is expected to realize industrialized production through a roll-to-roll process.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials, specifically relating to an asymmetric benzodithiophene dione compound, its prepared electron donor polymer, and its applications. Background Technology

[0002] Organic solar cells have attracted considerable attention from researchers due to their potential for industrial production. In organic solar cells, the active materials are the key factor determining cell efficiency. In particular, the benzodithiophene dione unit, as an important electron-deficient unit, has received widespread attention due to its good planarity, electron-withdrawing ability, and self-assembly properties. Many high-performance DA alternating copolymer donor materials, such as PM6 and PM7, are prepared using benzodithiophene dione as the electron-deficient unit. In addition, the benzodithiophene dione unit also exhibits good performance in the field of non-fullerene acceptor materials. The inventors prepared novel non-fullerene acceptors BDDEH-4F and BDDBO-4F (J. Mater. Chem. A, 2023, 11, 3437-3445 and patent application: CN202210781211.8) by introducing symmetrical phenyl-substituted benzodithiophene dione units as the central core of simple fused-ring acceptor materials. The non-covalent bonds within the BDDEH-4F molecule ensure good planarity and molecular stacking, which is beneficial for achieving good charge transport and active layer morphology. Ultimately, when blended with PM6 to prepare organic solar cells, it achieves good battery device performance: open-circuit voltage of 0.88 volts, short-circuit current of 22.57 mA / cm², fill factor of 63.38, and energy conversion efficiency of 12.59%. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an asymmetric benzodithiophene dione compound.

[0004] Another object of the present invention is to provide a method for preparing the asymmetric benzodithiophene dione compound.

[0005] Another object of the present invention is to provide a monomer containing an asymmetric benzodithiophene dione structure.

[0006] Another object of the present invention is to provide an electron donor polymer containing an asymmetric benzodithiophene dione structure.

[0007] Another object of the present invention is to provide a method for preparing the electron donor polymer containing the asymmetric benzodithiophene dione structure.

[0008] Another object of the present invention is to provide an organic photovoltaic cell device.

[0009] The above-mentioned objectives of the present invention are achieved through the following technical solutions: An asymmetric benzodithiophene dione compound having the structure shown in formula (I):

[0010] (I) Where Ar is a C4~C column with or without substituents. 20 aryl or heteroaryl, R is C1~C 24 The alkyl group is a straight-chain or branched halogenated or non-halogenated alkyl group, where X is a halogen; the substituent is selected from any one or more of fluorine, chlorine, bromine, iodine, C2-C6 alkenyl, C2-C6 alkynyl, hydroxyl, amino, acyl, carboxyl, C2-C6 ester, cyano, and nitro groups.

[0011] The present invention introduces an aromatic ring on one side of one of the thiophene rings of benzodithiophene dione and an alkyl chain on the other side, so that it has an asymmetric structure.

[0012] In this application, the acyl group refers to the -CO-M structure, where M can be C1~C2. 24 Straight-chain or branched halogenated or non-halogenated alkyl groups or C4~C 20 Aryl or heteroaryl.

[0013] In this application, heteroaryl refers to an aryl group containing an N atom, an O atom, or a S atom.

[0014] Preferably, the Ar is a phenyl group with or without substituents.

[0015] Preferably, the substituent is selected from any one or more of fluorine, chlorine, bromine, iodine or cyano.

[0016] Preferably, R is C8~C 24 Straight-chain or branched halogenated or non-halogenated alkyl groups.

[0017] In this invention, halogenation refers to the substitution of one or more hydrogen atoms on an alkyl group by a halogen.

[0018] The method for preparing the asymmetric benzodithiophene dione compound includes the following steps: reacting oxalyl chloride, The reaction first yields an intermediate product, which then reacts with... The reaction yields the asymmetric benzodithiophene dione compound.

[0019] It can be done and It is obtained by coupling in the presence of a palladium catalyst and a base.

[0020] In one specific embodiment, the palladium catalyst may be divalent palladium. More specifically, the palladium catalyst may be palladium acetate.

[0021] In one specific embodiment, the base can be a base commonly used in palladium coupling reactions. More specifically, the base can be potassium carbonate.

[0022] Oxaloyl chloride, The reaction that yields the intermediate product can be carried out with reference to existing techniques.

[0023] Preferably, the intermediate product and The reaction was carried out by dissolving in ultra-dry dichloromethane and adding aluminum trichloride under ice bath conditions.

[0024] A monomer containing an asymmetric benzodithiophene dione structure has the structure shown in formula (II):

[0025] (II); Where Ar is a C4~C column with or without substituents. 20 aryl or heteroaryl, R is C1~C 24 The alkyl group is a straight-chain or branched halogenated or non-halogenated alkyl group, where Y is Br or I; the substituent is selected from any one or more of fluorine, chlorine, bromine, iodine, C2-C6 alkenyl, C2-C6 alkynyl, hydroxyl, amino, acyl, carboxyl, C2-C6 ester, cyano, and nitro groups.

[0026] The method for preparing the monomer containing the asymmetric benzodithiophene dione structure includes using the asymmetric benzodithiophene dione compound of formula (I) as a raw material, introducing a thiophene group by removing the X group, and then brominating or iodizing it.

[0027] An electron donor polymer having a structure as shown in formula (III):

[0028] (III) Where Ar is a C4~C column with or without substituents. 20 aryl or heteroaryl, R is C1~C 24 The alkyl group is a straight-chain or branched halogenated or non-halogenated alkyl group, wherein the substituent is selected from any one or more of fluorine, chlorine, bromine, iodine, C2-C6 alkenyl, C2-C6 alkynyl, hydroxyl, amino, acyl, carboxyl, C2-C6 ester, cyano, and nitro groups; 0 <x≤1。

[0029] In equation (Ⅲ), x can take any value within the specified interval. Preferably, the value of x is between 0.1 and 0.3. The inventors have found that when electron donor polymers within this range are used to make organic photovoltaic cell devices, they exhibit higher performance than existing electron donors with similar structures. Most preferably, the value of x is 0.1.

[0030] The method for preparing the electron donor polymer involves a polymerization reaction of a monomer with an asymmetric benzodithiophene dione structure as shown in formula (II), a BDD monomer, and an F-BDT monomer.

[0031] The method for preparing the electron donor polymer is carried out under an inert atmosphere, such as argon.

[0032] Application of the electron donor polymer in the fabrication of organic photovoltaic cell devices.

[0033] An organic photovoltaic cell device includes a photovoltaic active layer in which the electron donor polymer described in formula (Ⅲ) is used as an electron donor and Y6 material is used as an electron acceptor.

[0034] Unexpectedly, due to the asymmetric side chains of the electron donor polymer described in formula (III) as an electron donor, the crystallinity of the active layer material and the morphology of the active layer may be improved; the crystal coherence lengths of the blend films prepared based on PhEH10 and PhEH20 are 44.9 Å and 42.5 Å, respectively, which are greater than the coherence length of the same blend film based on PM6 (37.0 Å), thereby improving the dissociation and carrier transport inside the active layer, resulting in higher open-circuit voltage, short-circuit current and fill factor of the organic photovoltaic cell device.

[0035] An organic photovoltaic cell device uses ITO as the anode, PEDOT:PSS as the anode buffer layer, and the electron donor polymer described in formula (Ⅲ) as the electron donor and Y6 material as the electron acceptor in the photovoltaic active layer.

[0036] Compared with the prior art, the present invention has the following beneficial effects: This invention provides novel asymmetric benzodithiophene dione compounds and polymer materials containing asymmetric benzodithiophene dione units prepared from these compounds. These materials possess high green synthesis rates and green solvent processing potential, thus providing more material options and processing methods for their application in optoelectronic devices. Furthermore, the polymer materials with asymmetric benzodithiophene dione units provided by this invention exhibit high photoelectric conversion efficiency in photovoltaic devices and hold promise for industrial production via roll-to-roll processes. Attached Figure Description

[0037] Figure 1The NMR spectrum of EPBDD, a monomer containing an asymmetric benzodithiophene dione structure, synthesized in Example 1; Figure 2 The NMR spectrum of EPCNBDD, a monomer containing an asymmetric benzodithiophene dione structure, synthesized in Example 2; Figure 3 The absorption diagrams for PM6 and PhEH10 in solution and thin film are shown. Figure 4 Electrochemical curves for PM6 and PhEH10; Figure 5 The grazing incidence wide-angle X-ray scattering profile of the blend film; Figure 6 The device current-voltage curves for PM6 and PhEH10 are shown. Figure 7 The device current-voltage curves for PM6 and PhCNEH10 are shown. Detailed Implementation The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0038] Example 1 The preparation method of asymmetric benzodithiophene dione compounds is as follows: The reaction equation for asymmetric compound 3 is as follows:

[0039] Synthetic route of compound 2 Compound 1 (7.5 mmol, 1.47 g), bromobenzene (5 mmol, 785 mg), K₂CO₃ (7.5 mmol, 1.04 g), and palladium acetate (0.5 mmol, 1.2 mg) were added to a 50 mL double-necked round-bottom flask under argon protection. Then, 25 mL of N,N-dimethylacetamide was added. The reaction was carried out at 80 °C in the dark for 4 hours, and the endpoint was confirmed by TLC. The reaction solution was cooled to room temperature, quenched with water, extracted three times with ethyl acetate, washed three times with distilled water, and the organic phase was collected. The solution was dried over anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. The solution was then purified by silica gel chromatography (eluent: PE) to give compound 2 (817.3 mg, 60%) as a yellow liquid. 1H NMR (500 MHz, CDCl3) δ ppm: 7.57 (d, 2H), 7.35 (t, 3H), 7.20 (t, 1H), 7.12 (d, 1H), 2.74 (d, 2H), 1.6 (m, 1H), 1.35 (m, 8H), 0.88 (m, 6H).

[0040] Synthetic route of compound 3: Under argon protection, 2,5-dibromothiophene-3,4-dicarboxylic acid (3 mmol, 989.85 mg), 20 mL of ultradry dichloromethane, and 1 mL of ultradry DMF were added to a 50 mL two-necked round-bottom flask and stirred thoroughly until completely dissolved. Oxaloyl chloride (12 mmol, 1.53 g) was added dropwise at room temperature and the reaction was allowed to proceed overnight. The solvent was then removed by rotary evaporation to obtain a yellow intermediate, which was directly used for the next reaction without further processing. The yellow intermediate and compound 2 (3 mmol, 817.3 mg) were dissolved in ultradry dichloromethane, and aluminum trichloride (12 mmol, 1.6 g) was added in portions under ice bath conditions. After the addition was complete, the reaction was allowed to proceed to room temperature for 4 h, and the reaction endpoint was confirmed by TLC. After the reaction was complete, the reaction solution was poured into ice water, extracted three times with ethyl acetate, washed three times with distilled water, and the organic phase was collected. The organic phase was dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation. The product was then purified by silica gel chromatography (eluent: PE:DCM = 4:1) to obtain a yellow solid product (1.14 g, 67%). 1 H NMR (500 MHz, CDCl3) δ ppm: 7.60 (q, 2H), 7.44 (t, 3H), 3.4 (m, 2H), 1.81 (m, 1H), 1.33 (m, 8H), 0.88 (m, 6H).

[0041] The preparation of the electron-donating polymer PhEH10 containing an asymmetric benzodithiophene dione structure is shown in the following reaction formula:

[0042] Synthetic route of compound 5: Under argon protection, compound 3 (2 mmol, 1.14 g) and 2-tributyltinylthiophene (6 mmol, 2.24 g) were added to a 50 mL double-necked round-bottom flask and dissolved in 30 mL of ultra-dry o-xylene. Argon gas was continuously purged for 10 min to completely remove oxygen, and then Pd(PPh3)4 (0.12 mmol, 138 mg) was added. The reaction was carried out overnight at 110 °C. The endpoint was confirmed by TLC, and the reaction was cooled to room temperature after completion. The reaction solution was quenched in water, extracted three times with ethyl acetate, washed three times with distilled water, and the organic phase was collected. The solution was dried over anhydrous magnesium sulfate, filtered, and the organic solvent was removed by rotary evaporation. The solution was then purified by silica gel chromatography (eluent: PE:DCM = 4:1) to give a yellow solid product (1.1 g, 95%). 1 H NMR (500 MHz, CDCl3) δ ppm: 7.76 (m, 2H), 7.62 (q, 2H), 7.52 (d, 1H), 7.43 (m, 4H), 7.06-7.15 (m, 2H), 3.37 (d, 2H), 1.81 (m, H), 1.33 (m, 8H), 0.88 (m, 6H).

[0043] Synthetic route of EPBDD monomer containing an asymmetric benzodithiophene dione structure: In a 100 mL flask, compound 5 (2 mmol, 1.1 g) and 30 mL of chloroform were added, followed by the addition of NBS (4.2 mmol, 748 mg) in portions under ice bath conditions. The reaction was then carried out overnight at room temperature in the dark. The reaction endpoint was confirmed by TLC. The reaction solution was quenched with water, extracted three times with dichloromethane, washed three times with distilled water, and the organic phase was collected. The organic phase was dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation. The product was purified by silica gel chromatography (eluent: PE:DCM = 4:1) to give an orange-yellow solid product (1.3 g, 90%). 1 ¹H NMR (500 MHz, CDCl₃) δ ppm: 7.62 (m, 2H), 7.42–7.4 (m, 5H), 7.01–7.09 (m, 2H), 3.38 (m, 2H), 1.80 (m, 1H), 1.33 (m, 8H), 0.88 (m, 6H). See NMR for details. Figure 1 .

[0044] Synthetic route of polymer PhEH10: Under argon protection, BDD (0.09 mmol), EPBDD (0.01 mmol), and F-BDT (0.1 mmol) monomers were weighed and added to a two-necked flask, along with 5 ml of o-xylene. Argon gas was continuously purged for 15 min, followed by the addition of 3%-5% tetraphenylphosphine palladium. After thorough stirring, the mixture was purged for another 30 min. The reaction was heated to 110 °C and allowed to react for 48 h. After the reaction was complete, the reaction solution was dropped into methanol to obtain a solid polymer. After filtration, the polymer was extracted using a Soxhlet extractor with methanol, acetone, n-hexane, ethyl acetate, dichloromethane, and chloroform. Finally, the chloroform solution was concentrated and precipitated in methanol to obtain the black solid polymer PhEH10.

[0045] PhEH10: Black solid, yield 83%, GPC: Mn=30.5 kDa, PDI: 2.35.

[0046] Using a similar method, by adjusting BDD (0.08 mmol), EPBDD (0.02 mmol), and F-BDT (0.1 mmol), a black solid polymer PhEH20 was prepared with a yield of 80%, GPC: Mn = 30.2 kDa, and PDI: 2.13.

[0047] We also performed absorption and electrochemical energy level tests on the polymer PhEH10 prepared in Example 1. Specific test results are shown in the figures below. Figure 3 as well as Figure 4 As shown. By Figure 3 As can be seen, the maximum absorption peaks of the polymer PhEH10 obtained in Example 1 in solution and film are 617 nm and 622 nm, respectively. The electrochemical energy levels HOMO and LUMO, calculated by formula using ferrocene as a reference, are -5.51 eV and -3.73 eV, respectively.

[0048] Example 2 The fabrication and performance of an organic photovoltaic cell device using ITO as the anode, polymers PhEH10 and PhEH20 as electron donors, and Y6 as the electron acceptor as the active layer material in Example 1.

[0049] The structure of the organic photovoltaic cell device with ITO as the anode is: ITO / PEDOT:PSS / polymer PhEH10 / PhEH10 / PhEH20:Y6=1:1 / PNDITF3N-Br / Ag. The fabrication process is as follows: using pre-cleaned ITO glass as the anode, a 30nm layer of PEDOT:PSS is spin-coated onto the ITO glass as an anode buffer layer. After vacuum drying, a photovoltaic active layer of approximately 120nm (polymer PhEH10 / PhEH20:Y6=1:1, by weight) is spin-coated. After drying at 150℃ for 15 minutes, PNDITF3N-Br (5nm) is spin-coated onto the top of the active layer as a cathode interface layer, and then a 100nm silver electrode is deposited on top of the PNDITF3N-Br. The battery characteristics were measured under AM1.5 simulated sunlight at 100 mW / cm². The PhEH10-based battery device exhibited an open-circuit voltage of 0.841 volts, a short-circuit current of 26.8 mA / cm², a fill factor of 75.8, and a power conversion efficiency of 17% (without any additives). The PhEH20-based battery device exhibited an open-circuit voltage of 0.84 volts, a short-circuit current of 26.2 mA / cm², a fill factor of 74.1, and a power conversion efficiency of 16.3% (without any additives).

[0050] This is significantly higher than the energy conversion efficiency of PM6:Y6-based battery devices (open-circuit voltage of 0.840 volts, short-circuit current of 25.4 mA / cm², fill factor of 74.8, and energy conversion efficiency of 15.9%). The specific JV curve is shown below. Figure 6 As shown.

[0051] Table 1. Summary of photovoltaic device performance of the polymer PhEH10 prepared in Example 1.

[0052]

[0053] Table 1 summarizes the photovoltaic performance parameters of organic photovoltaic cells prepared by blending PM6 and Y6, as well as organic photovoltaic cells prepared by blending polymer donors based on asymmetricly substituted benzodithiophene dione units with Y6 acceptors. It can be seen that the organic photovoltaic cell prepared in Example 1 using polymer PhEH10 / PhEH20 as an electron donor exhibits higher energy conversion efficiency, mainly due to the higher open-circuit voltage, short-circuit current, and fill factor of the related devices. Figure 5 Based on the information, we can calculate that the crystal coherence lengths of the PhEH10 and PhEH20 blend films are 44.9 Å and 42.5 Å, respectively, which are greater than the coherence length of the PM6-based blend film (37.0 Å), resulting in a more ordered morphology that is beneficial for exciton generation, separation and transport.

[0054] Example 3 Preparation of benzodithiophene dione units with asymmetric benzonitrile side chain substitution: The reaction equation for asymmetric compound 7 is as follows:

[0055] Synthetic route of compound 6 Compound 1 (7.5 mmol, 1.47 g), 4-bromobenzonitrile (5 mmol, 910 mg), K₂CO₃ (7.5 mmol, 1.04 g), and palladium acetate (0.5 mmol, 1.2 mg) were added to a 50 mL double-necked round-bottom flask under argon protection. Then, 25 mL of N,N-dimethylacetamide was added. The reaction was carried out at 80 °C in the dark for 4 hours, and the endpoint was confirmed by TLC. The reaction solution was cooled to room temperature, quenched with water, extracted three times with ethyl acetate, washed three times with distilled water, and the organic phase was collected. The solution was dried over anhydrous magnesium sulfate, filtered, and the solvent was evaporated by rotary evaporation. The solution was then purified by silica gel chromatography (eluent: PE) to give a yellow liquid compound 6 (892.4 mg, 60%). 1 H NMR (500 MHz, CDCl3) δ ppm: 7.60 (d, 4H), 7.24 (t, 1H), 6.78 (t, 1H), 2.78 (d, 2H), 1.6 (m, 1H), 1.35 (m, 8H), 0.88 (m, 6H).

[0056] Synthetic route of compound 7: Under argon protection, 2,5-dibromothiophene-3,4-dicarboxylic acid (3 mmol, 989.85 mg), 20 mL of ultradry dichloromethane, and 1 mL of ultradry DMF were added to a 50 mL two-necked round-bottom flask and stirred thoroughly until completely dissolved. Oxaloyl chloride (12 mmol, 1.53 g) was added dropwise at room temperature and the reaction was allowed to proceed overnight. The solvent was then removed by rotary evaporation to obtain a yellow intermediate, which was directly used for the next reaction without further processing. The yellow intermediate and compound 6 (3 mmol, 892.4 mg) were dissolved in ultradry dichloromethane, and aluminum trichloride (12 mmol, 1.6 g) was added in portions under ice bath conditions. After the addition was complete, the reaction was allowed to return to room temperature for 4 h, and the reaction endpoint was confirmed by TLC. After the reaction was complete, the reaction solution was poured into ice water, extracted three times with ethyl acetate, washed three times with distilled water, and the organic phase was collected. The organic phase was dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation. The product was then purified by silica gel chromatography (eluent: PE:DCM = 4:1) to give a yellow solid compound 7 (1.18 g, 67%). 1H NMR (500 MHz, CDCl3) δppm: 7.60 (q, 2H), 7.44 (t, 3H), 3.4 (m, 2H), 1.81 (m, 1H), 1.33 (m, 8H), 0.88 (m, 6H).

[0057] The preparation of polymer PhCNEH10 follows the reaction formula below:

[0058] Synthesis of EPCNBDD, a monomer containing an asymmetric benzodithiophene dione structure: Under argon protection, compound 7 (2 mmol, 1.18 g) and 2-tributyltinylthiophene (6 mmol, 2.24 g) were added to a 50 mL double-necked round-bottom flask and dissolved in 30 mL of ultra-dry o-xylene. Argon gas was continuously purged for 10 min to completely remove oxygen, and then Pd(PPh3)4 (0.12 mmol, 138 mg) was added. The reaction was carried out overnight at 110 °C. The reaction endpoint was confirmed by TLC, and the mixture was cooled to room temperature after the reaction was complete. The reaction solution was quenched in water, extracted three times with ethyl acetate, washed three times with distilled water, and the organic phase was collected. The organic phase was dried over anhydrous magnesium sulfate, filtered, and the organic solvent was removed by rotary evaporation. The product was then purified by silica gel chromatography (eluent: PE:DCM = 4:1) to give a yellow solid product (1.19 g, 95%). Then, in a 100 mL flask, the above-mentioned yellow solid compound 4 (2 mmol, 1.19 g) and 30 mL of chloroform were added, and NBS (4.2 mmol, 748 mg) was added in portions under ice bath conditions. The reaction was then carried out overnight at room temperature in the dark. The reaction endpoint was confirmed by TLC. The reaction solution was quenched with water, extracted three times with dichloromethane, washed three times with distilled water, and the organic phase was collected. The organic phase was dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation. The product was purified by silica gel column chromatography (eluent: PE:DCM = 4:1) to give an orange-yellow solid product (1.3 g, 90%). ¹H NMR (500 MHz, CDCl₃) δ ppm: 7.62 (m, 4H), 7.42–7.4 (m, 2H), 7.01–7.09 (m, 2H), 3.38 (m, 2H), 1.80 (m, 1H), 1.33 (m, 8H), 0.88 (m, 6H). See NMR for details. Figure 2 .

[0059] Synthetic route of polymer PhCNEH10: Under argon protection, BDD (0.09 mmol), EPCNDBD (0.01 mmol), and F-BDT (0.1 mmol) monomers were weighed and added to a two-necked flask, along with 5 ml of o-xylene. Argon gas was continuously purged for 15 min, followed by the addition of 3%-5% tetraphenylphosphine palladium. After thorough stirring, the mixture was purged for another 30 min. The reaction was heated to 110 °C and allowed to proceed for 48 h. After the reaction was complete, the reaction solution was dropped into methanol to obtain a solid polymer. After filtration, the polymer was extracted using a Soxhlet extractor with methanol, acetone, n-hexane, ethyl acetate, dichloromethane, and chloroform. Finally, the chloroform solution was concentrated and precipitated in methanol to obtain the black solid polymer PhCNEH10.

[0060] PhCNEH10: Black solid, yield 83%, GPC: Mn = 25.0 kDa, PDI: 1.98 We also performed electrochemical energy level tests on the polymer PhCNEH10 of Example 3 using the same method as in Example 1, and the electrochemical energy levels HOMO and LUMO calculated by the formula were -5.53 eV and -3.77 eV, respectively, with an optical band gap of 1.76 eV.

[0061] Example 4 The fabrication and performance of an organic photovoltaic cell device using ITO as the anode, polymer PhCNEH10 as the electron donor and Y6 as the electron acceptor in Example 1.

[0062] The structure of the organic photovoltaic cell device with ITO as the anode is: ITO / PEDOT:PSS / polymer donor based on benzonitrile-based asymmetric side chain substitution of benzodithiophene dione prepared in Example 3: Y6=1:1 / PNDITF3N-Br / Ag. The device fabrication process is as follows: using pre-cleaned ITO glass as the anode, a 30nm layer of PEDOT:PSS is spin-coated onto the ITO glass as an anode buffer layer. After vacuum drying, a photovoltaic active layer of approximately 120nm (polymer donor based on asymmetric side chain substitution of benzodithiophene dione prepared in Example 1: Y6=1:1, by weight) is spin-coated. After drying at 150°C for 15 minutes, PNDITF3N-Br (5nm) is spin-coated onto the top of the active layer as a cathode interface layer, and then a 100nm silver electrode is deposited on PNDITF3N-Br. The battery characteristics were measured under AM1.5 simulated sunlight at 100 mW / cm². The PhCNEH10-based battery device exhibited an open-circuit voltage of 0.83 volts, a short-circuit current of 26.21 mA / cm², a fill factor of 76.09, and a power conversion efficiency of 16.49%. These figures are significantly higher than the power conversion efficiency of the PM6:Y6-based battery device (open-circuit voltage of 0.840 volts, short-circuit current of 25.4 mA / cm², fill factor of 74.8, and power conversion efficiency of 15.9%). Specific JV curves are shown below. Figure 7 As shown.

[0063] Table 2. Summary of photovoltaic device performance using the polymer PhCNEH10 electron donor prepared in Example 3.

[0064]

[0065] As shown in Table 2, it can be seen that the organic photovoltaic cell prepared by the polymer PhCNEH10 electron donor in Example 3 has a higher energy conversion efficiency than the comparative device of PM6:Y6. This is mainly due to the higher short-circuit current and fill factor of the related device. This may be due to the introduction of asymmetric side chains, which improves the crystallinity and morphology of the active layer material, and enhances the dissociation and carrier transport inside the active layer.

[0066] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An asymmetric benzodithiophene dione compound, characterized in that, The asymmetric benzodithiophene dione compound has the structure shown in formula (I): （Ⅰ） Where Ar is a phenyl group with or without a substituent, and R is a C1~C2 phenyl group. 24 The alkyl group is a straight-chain or branched halogenated or non-halogenated alkyl group, where X is a halogen; the substituent is selected from any one or more of fluorine, chlorine, bromine, iodine, C2-C6 alkenyl, C2-C6 alkynyl, hydroxyl, amino, carboxyl, C2-C6 ester, cyano, and nitro groups.

2. The asymmetric benzodithiophene dione compound according to claim 1, characterized in that, The R is C8~C 24 Straight-chain or branched halogenated or non-halogenated alkyl groups.

3. The method for preparing the asymmetric benzodithiophene dione compound according to claim 1 or 2, characterized in that, The steps include: oxalyl chloride, The reaction first yields an intermediate product, which then reacts with... The reaction yields the asymmetric benzodithiophene dione compound.

4. A monomer containing an asymmetric benzodithiophene dione structure, characterized in that, It has the structure shown in equation (II): （Ⅱ）； Where Ar is a phenyl group with or without a substituent, and R is a C1~C2 phenyl group. 24 The alkyl group is a straight-chain or branched halogenated or non-halogenated alkyl group, where Y is Br or I; the substituent is selected from any one or more of fluorine, chlorine, bromine, iodine, C2-C6 alkenyl, C2-C6 alkynyl, hydroxyl, amino, carboxyl, C2-C6 ester, cyano, and nitro groups.

5. An electron donor polymer, characterized in that, The electron donor polymer has the structure shown in formula (Ⅲ): （Ⅲ） Where Ar is a phenyl group with or without a substituent, and R is a C1~C2 phenyl group. 24 The alkyl group is a straight-chain or branched halogenated or non-halogenated alkyl group, wherein the substituent is selected from any one or more of fluorine, chlorine, bromine, iodine, C2-C6 alkenyl, C2-C6 alkynyl, hydroxyl, amino, carboxyl, C2-C6 ester, cyano, and nitro groups; and the value of x is in the range of 0.1 to 0.

3.

6. The method for preparing the electron donor polymer according to claim 5, characterized in that, It is obtained by polymerization reaction of the monomer containing the asymmetric benzodithiophene dione structure as described in claim 4, the BDD monomer, and the F-BDT monomer.

7. The application of the electron donor polymer of claim 5 in the preparation of organic photovoltaic cell devices.

8. An organic photovoltaic cell device, characterized in that, It includes a photovoltaic active layer using the electron donor polymer as described in claim 5 as the electron donor and Y6 material as the electron acceptor.

9. An organic photovoltaic cell device, characterized in that, A photovoltaic active layer consisting of ITO as the anode, PEDOT:PSS as the anode buffer layer, the electron donor polymer as described in claim 5 as the electron donor, and Y6 material as the electron acceptor.

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