Biphenyl sulfide derivatives, methods for preparing the same, and perovskite solar cells

Abstract

The present application relates to the technical field of perovskite solar cells, and particularly relates to a diphenyl sulfide derivative, a preparation method thereof and a perovskite solar cell. The compound has dual functions of defect passivation and carrier transport through unique molecular structure design, and can effectively regulate the crystallization behavior of a perovskite thin film. When the compound is added to a perovskite precursor solution, the coordination of sulfur atoms and lead ions in the perovskite and the interaction of halogen atoms and lattice defects can significantly reduce the defect state density of the perovskite thin film, inhibit non-radiative recombination and ion migration, and optimize the charge transport path, thereby improving the open-circuit voltage, fill factor and power conversion efficiency of the perovskite device. In addition, the synthesis path and application method of the diphenyl sulfide derivative provided by the present application have the advantages of simple operation, controllable cost and great industrialization potential, and provide a new scheme for the preparation of high-efficiency and stable perovskite solar cells.

Description

Technical Field

[0001] This invention relates to the field of perovskite solar cell technology, specifically to biphenyl sulfide derivatives, their preparation methods, and perovskite solar cells. Background Technology

[0002] Perovskite solar cells (PSCs) have achieved a leap in photoelectric conversion efficiency from less than 3% to over 26% in just over a decade due to their advantages such as high light absorption coefficient, excellent carrier mobility, tunable bandgap, and simple fabrication process, making them one of the core research directions for next-generation photovoltaic technology. However, existing perovskite devices still face two major bottlenecks: first, perovskite thin films are prone to grain boundary defects and halogen vacancies during crystallization, leading to severe nonradiative recombination of carriers and limiting open-circuit voltage and fill factor; second, ion migration and phase separation easily occur under light, humidity, and thermal environments, resulting in rapid performance degradation and making it difficult to meet the stability requirements for commercial applications.

[0003] Additive modification is an efficient strategy to solve the above problems. By introducing trace amounts of functional molecules into the perovskite precursor, crystallization kinetics can be regulated, defects can be passivated, and interfacial properties can be optimized. Currently reported additives include alkyl ammonium salts, phosphonates, and organic amines, but most additives only have a single function: some additives, such as long-chain alkyl ammonium salts, can passivate surface defects, but their large molecular steric hindrance hinders charge carrier transport; others, such as simple thiols, can regulate charge transport, but are prone to self-polymerization reactions, reducing film uniformity. In addition, some silicon-containing additives are sensitive to moisture in the preparation process and are prone to homopolymerization reactions that damage film quality, limiting their large-scale application.

[0004] In summary, existing perovskite additives still suffer from problems such as limited functionality, poor environmental adaptability, high preparation and application costs, and insufficient compatibility with the perovskite lattice, making it difficult to achieve synergistic effects in perovskite thin film defect passivation, carrier transport optimization, and device stability improvement. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides biphenyl sulfide derivatives, their preparation methods, and perovskite solar cells. This invention uses biphenyl sulfide as the parent core, with sulfur atoms coordinating to passivate lead vacancy defects in perovskite. Fluorine, chlorine, bromine, or methoxy substituents bind and passivate grain boundary defects while regulating the molecular structure to ensure carrier transport. The biphenyl conjugated structure constructs charge transport channels, and the sulfide bonds enhance stability. The derivatives possess both dual-site defect passivation and conjugated carrier transport functions, achieving a balance between passivation and transport, and a synergistic improvement in efficiency and stability. This fundamentally differs from existing single-functional additives, solving the core bottleneck of perovskite devices at the molecular level.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The first objective of this invention is to provide a biphenyl sulfide derivative, the structure of which is shown below: ; Wherein, R is a halogen or a methoxy group, and the methoxy group is CH3O-. Preferably, the halogen is fluorine, chlorine, or bromine.

[0007] It should be noted that existing perovskite additives have limited functionality, limited stability improvement, and complex synthesis. Therefore, developing bifunctional additives that combine defect passivation and carrier transport performance, excellent environmental stability, and good compatibility with the perovskite lattice is key to overcoming the performance and stability bottlenecks of perovskite devices. Based on the concept of molecular structure design, this invention introduces thioalkyl compounds with specific coordinating groups and conjugated structures to synergistically optimize the properties of perovskite thin films through multiple mechanisms, providing a new pathway for the preparation of high-performance PSCs. Specifically, the biphenyl sulfide derivatives provided in this invention, such as... Figure 1 As shown, multiple performance optimizations are achieved through the synergistic effect of multiple functional groups. Addressing the shortcomings of existing single-function perovskite additives, a molecular structure is designed around the dual functions of defect passivation and carrier transport. Using biphenyl sulfide as the parent core, sulfur atoms coordinate to passivate lead vacancy defects in perovskite, while fluorine, chlorine, bromine, or methoxy substituents bind and passivate grain boundary defects and regulate the molecular structure to ensure carrier transport. The biphenyl conjugated structure constructs charge transport channels, and the sulfide bond enhances stability. This design enables the derivative to possess both dual-site defect passivation and conjugated carrier transport functions, achieving a balance between passivation and transport, and a synergistic improvement in efficiency and stability. This fundamentally differs from existing single-function additives, solving the core bottleneck of perovskite devices at the molecular level.

[0008] In the preferred embodiment of this invention, fluorine, chlorine, and bromine are used as halogens because: iodobiphenyls have low reactivity, leading to poor derivative preparation efficiency and low yield. Furthermore, introducing additional iodide ions exacerbates perovskite ion migration. The steric hindrance and electronic effects of iodine atoms disrupt bifunctional synergy. The introduction of iodide ions fails to meet the core requirements of this invention for biphenyl sulfide derivatives.

[0009] In a preferred embodiment of the present invention, the biphenyl sulfide derivative has one of the following structures: .

[0010] A second objective of this invention is to provide a method for preparing the above-mentioned biphenyl sulfide derivatives, comprising the following steps: In a reaction system consisting of a base, a palladium-based catalyst, a phosphine ligand, and a solvent, a coupling reaction was carried out using 3-fluorothiophenol and halobiphenyls as raw materials to obtain biphenyl sulfide derivatives.

[0011] It should be noted that this reaction follows the classical cyclic mechanism of palladium-catalyzed oxidative addition-coordination-reductive elimination. Using 3-fluorothiophenol and halobiphenyl as substrates, the CS bond is constructed in a palladium / phosphine catalytic system under alkaline conditions. Through catalyst activation, oxidative addition, sulfide anion coordination, and reductive elimination, the target product, a biphenyl sulfide derivative, is generated.

[0012] In the reaction process, potassium tert-butoxide, tris(dibenzylacetone)dipalladium, and bis(2-diphenylphosphine) ether act synergistically as core catalytic components to ensure the directional and efficient conduct of the reaction. Potassium tert-butoxide is a strong base that can abstract hydrogen atoms from the thiol group of 3-fluorobenzylthiophenol to form highly active aryl thiophene anions, providing substrates for nucleophilic substitution, while neutralizing hydrogen halides to maintain the basicity of the system and prevent catalyst deactivation. Tris(dibenzylacetone)dipalladium is a zero-valent palladium precursor catalyst, and the dissociated Pd(0) serves as the catalytic active center, achieving chemical bond activation and reconstruction through coordination. Bis(2-diphenylphosphine) ether, as a phosphine ligand, forms a stable palladium-phosphine complex catalyst with Pd(0), which can not only improve the stability of the palladium catalyst and prevent palladium atom aggregation and deactivation, but also regulate its electronic effects and steric hindrance, optimizing reaction activity and selectivity.

[0013] The specific preparation process of biphenyl sulfide derivatives is as follows: 3-fluorothiophenol, halobiphenyl, potassium tert-butoxide, tris(dibenzylacetone)dipalladium, and bis(2-diphenylphosphine) ether are added to a reaction flask; the reaction solvent is injected, and the mixture is heated to the reaction temperature and then refluxed; after the reaction is completed, deionized water is added to the cooled reaction mixture, followed by extraction with ethyl acetate. The insoluble matter is filtered through a diatomaceous earth funnel, and an appropriate amount of anhydrous sodium sulfate is added to the solution. The mixture is allowed to stand and dry for 2 hours, and the residual water in the organic phase is removed by utilizing the strong hygroscopic property of anhydrous sodium sulfate. After drying, the anhydrous sodium sulfate is removed again by filtration. The filtered organic phase is transferred to a rotary evaporator and concentrated under reduced pressure. Toluene solvent is recovered to obtain a brownish-yellow oily crude product. The crude product is separated and purified by silica gel column chromatography. A mixed solution of petroleum ether and ethyl acetate with a volume ratio of 10:1 is used as the eluent. The target component is collected by gradient elution and concentrated by rotary evaporation to obtain the biphenyl sulfide derivatives. The amount of deionized water used is 50 mL to 100 mL, the amount of ethyl acetate used is 80 mL to 160 mL, and the reduced pressure conditions are 45 °C and 0.08 MPa.

[0014] In a preferred embodiment of the present invention, the halogenated biphenyl is 3-bromo-4-fluorobiphenyl, 3-bromo-4-chlorobiphenyl, 4-bromo-3-iodobiphenyl, or 3-bromo-4-methoxybiphenyl.

[0015] In a preferred embodiment of the present invention, the molar ratio of 3-fluorothiophenol to halobiphenyl is 1:0.9~0.95, the molar ratio of 3-fluorothiophenol to base is 1:1.3~1.5, and the base is potassium tert-butoxide; the molar ratio of 3-fluorothiophenol to palladium-based catalyst is 1:0.01~0.05, and the palladium-based catalyst is tris(dibenzylacetone)dipalladium; the molar ratio of 3-fluorothiophenol to phosphine ligand is 1:0.01~0.06, and the phosphine ligand is bis(2-diphenylphosphine) ether.

[0016] In a preferred embodiment of the present invention, the coupling reaction is carried out at a temperature of 110°C for 5 to 16 hours, using toluene as the solvent, with a volume of 50 mL to 120 mL.

[0017] In a preferred embodiment of the present invention, the preparation method of 3-bromo-4-methoxybiphenyl includes the following steps: under a protective gas atmosphere, using 3-bromo-4-fluorobiphenyl and sodium methoxide as raw materials, a solvent is added to carry out a substitution reaction to obtain 3-bromo-4-methoxybiphenyl.

[0018] In a preferred embodiment of the present invention, the molar ratio of 3-bromo-4-fluorobiphenyl to sodium methoxide is 1:2, the solvent is N,N-dimethylformamide, the amount used is 80 mL, the temperature is 120 °C, the time is 8 h, and the protective gas is nitrogen.

[0019] The specific preparation process of 3-bromo-4-methoxybiphenyl is as follows: 3-bromo-4-fluorobiphenyl, sodium methoxide and N,N-dimethylformamide are added to a reaction flask and heated to 120°C for 8 hours under a nitrogen atmosphere. After the reaction is completed, the reaction mixture is extracted with water and ethyl acetate, the organic phase is dried with anhydrous sodium sulfate, the solvent is concentrated under reduced pressure, and the reaction product is separated by high vacuum distillation to obtain 3-bromo-4-methoxybiphenyl.

[0020] In a preferred embodiment of the present invention, the preparation method of 4-bromo-3-iodobiphenyl includes the following steps: using 4-bromo-3-nitrobiphenyl and iron powder as raw materials, a reduction reaction is carried out in a solvent system to obtain 4-bromo-3-aminobiphenyl; then, using 4-bromo-3-aminobiphenyl, sodium nitrite and potassium iodide as raw materials, an iodination reaction is carried out to obtain 4-bromo-3-iodobiphenyl.

[0021] In a preferred embodiment of the present invention, the molar ratio of 4-bromo-3-nitrobiphenyl to iron powder is 1:3, the solvent is ethanol; the reduction reaction temperature is 71°C, and the reduction time is 3 hours; the molar ratio of 4-bromo-3-aminobiphenyl to sodium nitrite is 1:1.1, the molar ratio of 4-bromo-3-aminobiphenyl to potassium iodide is 1:1.15, the iodination reaction temperature is 5°C, and the time is 1 hour.

[0022] The specific preparation process of 4-bromo-3-iodobiphenyl consists of two steps: the first step is the preparation of 4-bromo-3-aminobiphenyl, and the second step is the preparation of 4-bromo-3-iodobiphenyl.

[0023] The preparation process of 4-bromo-3-aminobiphenyl in the first step is as follows: Ethanol, acetic acid, concentrated hydrochloric acid, and 4-bromo-3-nitrobiphenyl are added to a reaction flask and magnetically stirred. The system is yellow and turbid. The temperature is raised to 73°C and refluxed. When the internal temperature reaches 71°C and the reflux is stable, iron powder is added in batches of 1g each time. A large number of bubbles are generated on the surface of the liquid phase. After all the powder is added, the reaction solution turns orange-red. After refluxing for 3 hours, the reaction is stopped by TLC. The temperature is lowered to 40°C, and 500mL of isopropyl acetate is added directly for extraction. After stirring thoroughly, 800mL of water is added to wash the salt. The mixture is stirred thoroughly for 20 minutes. The insoluble iron salt is filtered through a diatomaceous earth funnel, and the filtrate is collected. The filtrate is allowed to stand and separated. The aqueous phase is discarded because no product is found. The organic phase is washed three times with 500mL of water each time. The aqueous phase is discarded after separation. The solvent is concentrated under reduced pressure. The crude product is dried to obtain 4-bromo-3-aminobiphenyl. The volume ratio of ethanol to acetic acid is 225:135, the molar ratio of concentrated hydrochloric acid to 4-bromo-3-nitrobiphenyl is 32.36:161.81, and the mass concentration of concentrated hydrochloric acid is 37%.

[0024] The second step, the preparation of 4-bromo-3-iodobiphenyl, is as follows: 60 mL of concentrated hydrochloric acid is added to the reaction flask, and stirring is started. 4-bromo-3-aminobiphenyl is dissolved in 120 mL of ethyl acetate and added dropwise to the concentrated hydrochloric acid to form a salt. The mixture is then heated to 60°C and kept at this temperature for 1 hour. After the temperature is maintained, the mixture is cooled to -10°C. Sodium nitrite is dissolved in 19 mL of water to prepare a solution. The sodium nitrite solution is added dropwise to the reaction flask at 0°C, completing the addition in approximately 5 minutes. The system becomes a pale yellow and clear liquid. After the addition is complete, the mixture is kept at 0°C for 1 hour. Potassium iodide is dissolved in 46 mL of water to prepare a solution. The solution was added dropwise to the reaction flask at 0℃, during which nitrogen dioxide gas was generated. After the addition was complete, the reaction was kept at this temperature for 30 minutes. After the TLC reaction was completed, 500 mL of ethyl acetate and 400 mL of water were added to the reaction solution. The solution was extracted and washed with water. The insoluble matter was filtered through a diatomaceous earth funnel. The filtrate was allowed to stand and separated. The aqueous phase was discarded as no product was found. The organic phase was washed three times with 400 mL of water each time. The aqueous phase was then separated and discarded. The solvent was concentrated under reduced pressure. The reaction product was then separated by column chromatography using petroleum ether / ethyl acetate at a ratio of 20:1. The product was concentrated by column chromatography to finally obtain 4-bromo-3-iodobiphenyl.

[0025] The preparation method of the biphenyl sulfide derivatives is simple and the synthesis cost is low.

[0026] The third objective of this invention is to provide a perovskite solar cell, which comprises, from bottom to top, an FTO substrate, a hole transport layer, a perovskite layer, an electron transport layer, a buffer layer, and a metal electrode. An additive is added to the perovskite precursor solution in the perovskite layer, and the additive is the aforementioned biphenyl sulfide derivative.

[0027] The aforementioned biphenyl sulfide derivatives are used as perovskite additives in perovskite devices to achieve a synergistic improvement in device efficiency and stability. Specifically, when added to the perovskite precursor solution, they can significantly reduce the defect state density of the perovskite film through the coordination of sulfur atoms with lead ions in the perovskite and the interaction of halogen atoms with lattice defects, suppress nonradiative recombination and ion migration, and optimize charge transport paths, thereby improving the open-circuit voltage, fill factor, and power conversion efficiency of perovskite devices.

[0028] In a preferred embodiment of the present invention, the concentration of the biphenyl sulfide derivative added to the perovskite precursor solution is 0.1 mM to 0.3 mM.

[0029] Compared with the prior art, the beneficial effects of the present invention are: 10. This invention provides a biphenyl sulfide derivative, which, through a unique molecular structure design, possesses both defect passivation and carrier transport functions, effectively regulating the crystallization behavior of perovskite films. Specifically, biphenyl sulfide serves as the parent nucleus, with sulfur atoms coordinating to passivate lead vacancy defects in the perovskite. Fluorine, chlorine, bromine, or methoxy substituents bind and passivate grain boundary defects while regulating the molecular structure to ensure carrier transport. The biphenyl conjugated structure constructs charge transport channels, and the sulfide bonds enhance stability. This solves the technical problems of existing perovskite additives, such as limited functionality, poor environmental adaptability, high preparation and application costs, and insufficient compatibility with the perovskite lattice.

[0030] 2. This invention provides a perovskite solar cell. The use of biphenyl sulfide derivatives as a perovskite additive significantly improves the photoelectric conversion efficiency of the perovskite solar cell. Its core advantage stems from the strong coordination ability of chalcogen elements in the molecular structure and the spatial regulation effect of the biphenyl framework, which can precisely passivate uncoordinated Pb on the surface of the perovskite thin film. 2+ Ion vacancy defects significantly reduce nonradiative recombination losses, promote charge separation and transport, optimize carrier transport paths, and improve open-circuit voltage and fill factor. The modification process for this type of additive is simple and reproducible, providing an efficient path for efficiency optimization in the commercialization of perovskite solar cells.

[0031] 3. This invention provides a method for preparing biphenyl sulfide derivatives, which is characterized by simple operation, controllable cost, and great industrialization potential. Attached Figure Description

[0032] Figure 1 This is a structural diagram of the biphenyl sulfide derivatives of the present invention.

[0033] Figure 2 This is a structural diagram of the perovskite solar cell of the present invention.

[0034] Figure 3 The current-voltage curves of the perovskite solar cells of Application Examples 1 to 4 and Comparative Application Example 1 of the present invention are shown. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0037] The following specific examples will provide further explanation.

[0038] In this invention, potassium tert-butoxide is abbreviated as t-BuOK, tris(dibenzylacetone)dipalladium is abbreviated as Pd2(dba)3, bis(2-diphenylphosphine) ether is abbreviated as DPE-phos, toluene is abbreviated as Toluene, N,N-dimethylformamide is abbreviated as DMF, acetic acid is abbreviated as AcOH, ethanol is abbreviated as EtOH, sodium nitrite is abbreviated as NaNO2, and ethyl acetate is abbreviated as EA.

[0039] Example 1 The synthetic route for a biphenyl sulfide derivative, compound A1, is shown below: .

[0040] The synthesis process of the above compound A1 includes the following steps: Add 5.0 g (equivalent to 39.01 mmol of 3-fluorothiophenol), 9.31 g (equivalent to 37.06 mmol of 3-bromo-4-fluorobiphenyl), 6.57 g (equivalent to 58.52 mmol of t-BuOK), 1.07 g (equivalent to 1.17 mmol of Pd2(dba)3), and 1.26 g (equivalent to 2.34 mmol of DPE-phos) to the reaction flask; inject 60 mL of toluene as the reaction solvent, and heat to 110 °C and reflux for 5 h. After the reaction is complete, add 50 mL of deionized water to the cooled reaction mixture, followed by extraction with 80 mL of ethyl acetate. Filter the insoluble matter using a diatomaceous earth funnel, add an appropriate amount of anhydrous sodium sulfate to the solution, and allow to stand and dry for 2 hours. Use the strong hygroscopic property of anhydrous sodium sulfate to remove residual water from the organic phase. After drying, filter again to remove anhydrous sodium sulfate. The filtered organic phase was transferred to a rotary evaporator and concentrated under reduced pressure at 45°C and 0.08 MPa to recover the toluene solvent, yielding a brownish-yellow oily crude product. The crude product was purified by silica gel column chromatography using a 10:1 (v / v) mixture of petroleum ether and ethyl acetate as the eluent. The target component was collected by gradient elution and concentrated by rotary evaporation to obtain the pure target compound, compound A1. The mass was 9.85 g, with a yield of 84.60%.

[0041] Example 2 The synthetic route for a biphenyl sulfide derivative, compound A2, is shown below: .

[0042] The synthesis process of the above compound A2 includes the following steps: Add 4.5 g (equivalent to 35.11 mmol of 3-fluorothiophenol), 8.92 g (equivalent to 33.36 mmol of 3-bromo-4-chlorobiphenyl), 5.91 g (equivalent to 52.67 mmol of t-BuOK), 0.96 g (equivalent to 1.05 mmol of Pd2(dba)3), and 1.13 g (equivalent to 2.11 mmol of DPE-phos) to the reaction flask; inject 50 mL of toluene as the reaction solvent, and heat to 110 °C and reflux for 5 h. After the reaction is complete, add 50 mL of deionized water to the cooled reaction mixture, followed by 80 mL of ethyl acetate for extraction. Filter the insoluble matter using a diatomaceous earth funnel, add an appropriate amount of anhydrous sodium sulfate to the solution, and allow to stand and dry for 2 h. Utilize the strong hygroscopic property of anhydrous sodium sulfate to remove residual water from the organic phase. After drying, filter again to remove anhydrous sodium sulfate. Transfer the filtered organic phase to a rotary evaporator and concentrate under reduced pressure at 45 °C and 0.08 MPa. Recover the toluene solvent to obtain a brownish-yellow oily crude product. The crude product was separated and purified by silica gel column chromatography using a 10:1 (v / v) mixture of petroleum ether and ethyl acetate as the eluent. The target fraction was collected by gradient elution and concentrated by rotary evaporation to obtain the purified target compound, compound A2. The final product weighed 6.93 g, with a yield of 62.70%.

[0043] Example 3 The synthetic route for a biphenyl sulfide derivative, compound A3, is shown below: .

[0044] The synthesis process of the above compound A3 includes the following steps: The synthesis route for compound S1, 4-bromo-3-iodobiphenyl, is shown below: .

[0045] Step 1: Synthesis of compound 4-bromo-3-aminobiphenyl: .

[0046] Add 225 mL of ethanol, 135 mL of acetic acid, 1.18 g of concentrated hydrochloric acid (37 wt%, equivalent to 32.36 mmol), and 45 g of 4-bromo-3-nitrobenzene (161.81 mmol) to the reaction flask. Stir magnetically; the system becomes yellow and turbid. Heat to 73 °C and reflux. When the internal temperature reaches 71 °C and reflux is stable, add 27.11 g of iron powder (485.4 mmol) in 1 g portions. A large number of bubbles are generated on the surface of the liquid phase. After all the iron powder has been added, the reaction solution... The solution turned orange-red. After reflux for 3 hours, the reaction was stopped by TLC. The temperature was lowered to 40℃, and 500 mL of isopropyl acetate was added directly for extraction. After thorough stirring, 800 mL of water was added to wash the salt, and the mixture was stirred thoroughly for 20 minutes. The solution was filtered through a diatomaceous earth funnel to remove insoluble iron salts, and the filtrate was collected. The filtrate was allowed to stand and separated. The aqueous phase was discarded as no product was found. The organic phase was washed three times with 500 mL of water each time. The aqueous phase was discarded after separation. The solvent was concentrated under reduced pressure, and the crude product was dried to obtain 4-bromo-3-aminobiphenyl, with a yield of 34.25 g and a yield of 85.30%.

[0047] Step 2: Synthesis of compound 4-bromo-3-iodobiphenyl: .

[0048] Add 60 mL of 37 wt% concentrated hydrochloric acid to the reaction flask, start stirring, dissolve 30 g (equivalent to 120.91 mmol) of 4-bromo-3-aminobiphenyl in 120 mL of ethyl acetate, and add it dropwise to the concentrated hydrochloric acid to form a salt. Heat to 60 °C and maintain the temperature for 1 h. After the temperature maintenance, cool to -10 °C, dissolve 9.18 g (equivalent to 133 mmol) of sodium nitrite in 19 mL of water to prepare a solution, and add the sodium nitrite solution dropwise to the reaction flask while maintaining the temperature at 0 °C. The addition is completed in about 5 minutes, and the system becomes pale yellow and clear. Maintain the temperature at 0 °C for 1 h. Dissolve 23.08 g (equivalent to 139 mmol) of potassium iodide... A solution was prepared in 46 mL of water and added dropwise to the reaction flask at 0 °C. Nitrogen dioxide gas was generated during the addition. After the addition was complete, the reaction was kept at this temperature for 30 min. After the TLC reaction was completed, 500 mL of ethyl acetate and 400 mL of water were added to the reaction solution. The mixture was extracted and washed with water. The insoluble matter was filtered through a diatomaceous earth funnel. The filtrate was allowed to stand and separated. The aqueous phase was discarded as no product was found. The organic phase was washed three times with 400 mL of water each time. The aqueous phase was then separated and discarded. The solvent was concentrated under reduced pressure, and the reaction product was then separated by column chromatography using petroleum ether / ethyl acetate at a ratio of 20:1. The product was concentrated by column chromatography to finally obtain 4-bromo-3-iodobiphenyl, with a yield of 31.31 g and a yield of 72.14%.

[0049] Synthesis of S2 and compound A3: Add 10 g of 3-fluorothiophenol (equivalent to 78.02 mmol), 26.61 g of 4-bromo-3-iodobiphenyl (equivalent to 74.12 mmol), 13.13 g of t-BuOK (equivalent to 117.04 mmol), 3.57 g of Pd2(dba)3 (equivalent to 3.90 mmol), and 4.20 g of DPE-phos (equivalent to 7.80 mmol) to the reaction flask; inject 120 mL of toluene as the reaction solvent, heat to 110 °C and reflux for 16 h; after the reaction is complete, add 100 mL of deionized water to the cooled reaction mixture, followed by 160 mL of ethyl acetate for extraction, filter the insoluble matter through a diatomaceous earth funnel, add an appropriate amount of anhydrous sodium sulfate to the solution, let stand and dry for 2 hours, use the strong hygroscopic property of anhydrous sodium sulfate to remove the residual water in the organic phase, after drying, filter again to remove anhydrous sodium sulfate. The filtered organic phase was transferred to a rotary evaporator and concentrated under reduced pressure at 45°C and 0.08 MPa to recover the toluene solvent, yielding a brownish-yellow oily crude product. The crude product was purified by silica gel column chromatography using a 10:1 (v / v) mixture of petroleum ether and ethyl acetate as the eluent. The target component was collected by gradient elution and concentrated by rotary evaporation to obtain the purified target compound, compound A3. The final product weighed 13.26 g, with a yield of 47.30%.

[0050] Example 4 The synthetic route for a biphenyl sulfide derivative, compound A4, is shown below: .

[0051] The synthesis process of the above compound A4 includes the following steps: S1. Synthesis of intermediate 3-bromo-4-methoxybiphenyl: .

[0052] 10 g (equivalent to 39.83 mmol) of 3-bromo-4-fluorobiphenyl, 4.30 g (equivalent to 79.65 mmol) of sodium methoxide, and 80 mL of DMF were added to a reaction flask. The mixture was heated to 120 °C and reacted for 8 h under a nitrogen atmosphere. After the reaction was completed, the reaction mixture was extracted with water and ethyl acetate, the organic phase was dried over anhydrous sodium sulfate, the solvent was concentrated under reduced pressure, and the reaction product was separated by high-vacuum distillation to obtain the intermediate 3-bromo-4-methoxybiphenyl, with a mass of 9.45 g and a yield of 90.2%. The sodium methoxide was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0053] Synthesis of S2 and compound A4: .

[0054] Add 4.82 g (equivalent to 37.62 mmol of 3-fluorothiophenol), 9.0 g (equivalent to 34.20 mmol of 3-bromo-4-methoxybiphenyl), 5.76 g (equivalent to 51.30 mmol of t-BuOK), 0.47 g (equivalent to 0.68 mmol of Pd2(dba)3), and 0.74 g (equivalent to 1.37 mmol of DPE-phos) to the reaction flask; inject 110 mL of toluene as the reaction solvent, heat to 110 °C and reflux for 16 h; after the reaction is complete, add 90 mL of deionized water to the cooled reaction mixture, followed by 150 mL of ethyl acetate for extraction, filter the insoluble matter through a diatomaceous earth funnel, add an appropriate amount of anhydrous sodium sulfate to the solution, let stand and dry for 2 hours, and use the strong hygroscopic property of anhydrous sodium sulfate to remove the residual water in the organic phase. After drying, filter again to remove anhydrous sodium sulfate. The filtered organic phase was transferred to a rotary evaporator and concentrated under reduced pressure at 45°C and 0.08 MPa to recover the toluene solvent, yielding a brownish-yellow oily crude product. The crude product was purified by silica gel column chromatography using a 10:1 (v / v) mixture of petroleum ether and ethyl acetate as the eluent. The target component was collected by gradient elution and concentrated by rotary evaporation to obtain the purified target compound, compound A4. The final product weighed 8.03 g, with a yield of 75.60%.

[0055] Application Example 1 A perovskite solar cell, wherein the perovskite additive material in the perovskite solar cell is compound A1. The device structure of the perovskite solar cell is as follows. Figure 2 As shown, from bottom to top, the layers are FTO / hole transport layer / perovskite layer / electron transport layer / buffer layer / metal electrode, and the perovskite layer contains compound additives.

[0056] The above-mentioned method for preparing perovskite solar cells includes the following steps: S1. FTO Pretreatment: First, the 2.2mm thick FTO substrate was ultrasonically treated with deionized water, ethanol, and acetone for 15 minutes each. The cleaned FTO substrate was then placed in a forced-air drying oven and dried at 100℃ for 15 minutes. The dried FTO substrate was then placed in a UV ozone generator with a power of 30W and a treatment time of 25 minutes. Through the dual action of UV degradation and ozone oxidation, residual organic matter on the surface was further removed, while the hydrophilicity and surface energy of the substrate surface were improved. After treatment, the substrate was quickly transferred to a nitrogen glove box for later use.

[0057] S2. Preparation of the hole transport layer: Weigh Me-4PACz powder with a purity ≥99%, mix it with ultra-dry ethanol to prepare a Me-4PACz solution with a concentration of 1 mmol / L, and stir at room temperature for 30 minutes. Add 40 μL of filtered Me-4PACz solution evenly to the substrate surface, and set the spin-coating parameters: spin speed 4000 rpm, spin-coating time 30 seconds, acceleration 2000 rpm / s. Start the spin-coating program to allow the solution to spread evenly and form a thin film. After spin-coating, immediately transfer the substrate to a hot stage in a glove box and anneal at 100°C for 10 minutes under a nitrogen atmosphere to obtain a hole transport layer with a thickness of 30 nm. Me-4PACz refers to [4-(3,6-dimethyl-9H-carbazole-9-yl)butyl]phosphonic acid.

[0058] S3. Preparation of the perovskite light-absorbing layer: 639.65 mg of 99.99% pure PbI₂, 7.98 mg of 99.5% pure MABr, 41.29 mg of 99.99% pure PbBr₂, 433.05 mg of 99.5% pure FAI, and 19.49 mg of 99.99% pure CsI were dissolved in a mixed solution, which was prepared by mixing 800 μL of N,N-dimethylformamide and 200 μL of dimethyl sulfoxide. The mixture was magnetically stirred at room temperature for 4 hours to form a perovskite light-absorbing layer with the chemical formula CsI. 0.05 (MA 0.05 FA 0.95 ) 0.95 Pb(Br 0.05 I 0.95 A perovskite precursor solution containing 0.1 mM of compound A1 was added. The substrate with the Me-4PACz hole transport layer was fixed on a spin coater, and 50 μL of the perovskite precursor solution containing compound A1 was added dropwise. A two-stage spin coating program was used: stage 500 rpm / 5 seconds; stage 4000 rpm / 30 seconds. At 15 seconds into the second stage of spin coating, 100 μL of chlorobenzene antisolvent was rapidly added dropwise using a pipette. After spin coating, the substrate was immediately transferred to a hot stage in a glove box and annealed at 120°C for 30 minutes under a nitrogen atmosphere to obtain a perovskite layer with a thickness of 650 nm. MABr was methylamine bromide, and FAI was formamidinium iodide.

[0059] S4. Fabrication of the electron transport layer and buffer layer: The substrate with the perovskite layer is transferred to a thermal evaporation coating apparatus. The chamber is closed and the vacuum pump is started, evacuating the chamber until the vacuum level is below 5 × 10⁻⁶. -4 Pa. With C 60 The powder was used as the evaporation source, and the evaporation rate was controlled at 0.1 nm / s. When C... 60Evaporation was stopped when the layer thickness reached 30 nm. The process was then switched to a BCP evaporation source, with the evaporation rate controlled at 0.05 nm / s and the deposition thickness at 5 nm. The BCP was 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline.

[0060] S5. Preparation of metal electrodes: A layer of silver Ag with a thickness of 100 nm is deposited on the electron transport layer.

[0061] Application Example 2 The difference from Application Example 1 is that in the preparation of the perovskite layer, compound A1 in Example 1 is replaced with compound A2 in Example 2.

[0062] Application Example 3 The difference from Application Example 1 is that in the preparation of the perovskite layer, compound A1 in Example 1 is replaced with compound A3 in Example 3.

[0063] Application Example 4 The difference from Application Example 1 is that in the preparation of the perovskite layer, compound A1 in Example 1 is replaced with compound A4 in Example 4.

[0064] Comparative Application Example 1 The difference from Application Example 1 is that no diphenyl sulfide derivatives are added when preparing the perovskite layer.

[0065] The performance of the perovskite solar cells in Application Examples 1 to 4 and Comparative Application Example 1 was tested.

[0066] Table 1 shows the performance data of perovskite solar cells for different applications. Figure 3 Table 1 shows the current-voltage curves of the perovskite solar cells used in Application Examples 1 to 4 and Comparative Application Example 1 of this invention. Figure 3 It is evident that, through specific molecular structure design, the biphenyl sulfide derivatives of this invention, as additives to perovskite precursor solutions, can significantly improve the core photoelectric properties of perovskite solar cells. Compared to devices without these derivatives, the added devices exhibit varying degrees of positive improvements in open-circuit voltage, short-circuit current, and fill factor, ultimately leading to a significant increase in photoelectric conversion efficiency. The efficiency improvement ranges from 0.41% to 1.25%, with compound A3 achieving the highest photoelectric conversion efficiency of 21.84%, demonstrating the optimal modification effect. Its core advantage stems from the strong coordination ability of chalcogen elements and the spatial regulation effect of the biphenyl framework in the molecular structure, enabling precise passivation of uncoordinated Pb on the perovskite film surface. 2+Ion vacancy defects significantly reduce nonradiative recombination losses, promote charge separation and transport, optimize carrier transport paths, and improve open-circuit voltage and fill factor. The modification process for this type of additive is simple and reproducible, providing an efficient path for efficiency optimization in the commercialization of perovskite solar cells.

[0067] Table 1 Performance data of perovskite solar cells for different applications It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended scope of protection is intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0068] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of protection of this invention and its equivalents, this invention also intends to include these modifications and variations.

Claims

1. A biphenyl sulfide derivative, characterized in that, The structures of the biphenyl sulfide derivatives are shown below: ； Where R is a halogen or a methoxy group.

2. The biphenyl sulfide derivative according to claim 1, characterized in that, The biphenyl sulfide derivatives have one of the following structures: 。 3. A method for preparing a biphenyl sulfide derivative according to claim 1 or claim 2, characterized in that, Includes the following steps: In a reaction system consisting of a base, a palladium-based catalyst, a phosphine ligand, and a solvent, a coupling reaction was carried out using 3-fluorothiophenol and halobiphenyls as raw materials to obtain biphenyl sulfide derivatives.

4. The method for preparing biphenyl sulfide derivatives according to claim 3, characterized in that, The halogenated biphenyl is 3-bromo-4-fluorobiphenyl, 3-bromo-4-chlorobiphenyl, 4-bromo-3-iodobiphenyl, or 3-bromo-4-methoxybiphenyl.

5. The method for preparing biphenyl sulfide derivatives according to claim 3, characterized in that, The molar ratio of 3-fluorothiophenol to halobiphenyl is 1:0.9~0.95; the molar ratio of 3-fluorothiophenol to base is 1:1.3~1.5, and the base is potassium tert-butoxide; the molar ratio of 3-fluorothiophenol to palladium-based catalyst is 1:0.01~0.05, and the palladium-based catalyst is tris(dibenzylacetone)dipalladium; the molar ratio of 3-fluorothiophenol to phosphine ligand is 1:0.01~0.06, and the phosphine ligand is bis(2-diphenylphosphine) ether.

6. The method for preparing biphenyl sulfide derivatives according to claim 3, characterized in that, The coupling reaction was carried out at a temperature of 110℃ for 5 to 16 hours, using toluene as the solvent.

7. The method for preparing biphenyl sulfide derivatives according to claim 4, characterized in that, The preparation method of 3-bromo-4-methoxybiphenyl includes the following steps: Under a protective gas atmosphere, 3-bromo-4-fluorobiphenyl and sodium methoxide were used as raw materials, and a solvent was added to carry out a substitution reaction to obtain 3-bromo-4-methoxybiphenyl; the molar ratio of 3-bromo-4-fluorobiphenyl to sodium methoxide was 1:

2.

8. The method for preparing biphenyl sulfide derivatives according to claim 4, characterized in that, The preparation method of 4-bromo-3-iodobiphenyl includes the following steps: Using 4-bromo-3-nitrobiphenyl and iron powder as raw materials, a reduction reaction was carried out in a solvent system to obtain 4-bromo-3-aminobiphenyl; the molar ratio of 4-bromo-3-nitrobiphenyl to iron powder was 1:

3. Then, using 4-bromo-3-aminobiphenyl, sodium nitrite, and potassium iodide as raw materials, an iodination reaction was carried out to obtain 4-bromo-3-iodobiphenyl; the molar ratio of 4-bromo-3-aminobiphenyl to sodium nitrite was 1:1.1, and the molar ratio of 4-bromo-3-aminobiphenyl to potassium iodide was 1:1.

15.

9. A perovskite solar cell, characterized in that, The perovskite solar cell comprises, from bottom to top, an FTO substrate, a hole transport layer, a perovskite layer, an electron transport layer, a buffer layer, and a metal electrode. An additive is added to the perovskite precursor solution in the perovskite layer, and the additive is a biphenyl sulfide derivative as described in claim 1 or claim 2.

10. The perovskite solar cell according to claim 9, characterized in that, The concentration of the biphenyl sulfide derivative added to the perovskite precursor solution is 0.1 mM to 0.3 mM.

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