Multifunctional composite additive for perovskite / crystalline silicon laminated cell, and preparation method and application thereof

Abstract

According to the multifunctional composite additive for the perovskite / crystalline silicon laminated cell and the preparation method and application of the multifunctional composite additive, the composite additive is compounded by reasonably selecting components with specific functional groups, and a crystallization regulation component, an interface modification component and a stability enhancement component have a synergistic effect; and meanwhile, the bottlenecks of poor crystallization quality, serious interface charge recombination, insufficient stability and the like of the perovskite layer are solved, and the perovskite solar cell has good compatibility with a perovskite precursor solution, a crystalline silicon substrate and a transmission layer, can be directly applied to an existing laminated cell to improve the conversion efficiency and the long-term stability, and has a remarkable application prospect.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic materials technology, specifically to a multifunctional composite additive for perovskite / crystalline silicon tandem solar cells, its preparation method, and its application. Background Technology

[0002] Driven by global "dual carbon" goals, photovoltaic energy has become a core development direction for clean and renewable energy. Perovskite / crystalline silicon tandem solar cells, having broken through the theoretical conversion efficiency limit of single-crystal silicon cells, have become a research hotspot and a core direction for industrialization in the photovoltaic field. Currently, the conversion efficiency of laboratory-grade perovskite / crystalline silicon tandem solar cells has exceeded 33%, but industrialization still faces technical bottlenecks such as poor perovskite layer crystal quality, severe interfacial charge recombination, insufficient cell stability, and poor process compatibility, which greatly limit their large-scale production and commercial application.

[0003] Process additives and auxiliaries are key materials for regulating the battery fabrication process and optimizing device performance. They can effectively improve the crystallinity of perovskite thin films, reduce the density of interface defect states, and enhance interlayer compatibility and long-term stability. However, existing additives suffer from problems such as weak targeting, limited effects, and poor compatibility with tandem battery processes: single crystallization regulating additives cannot solve the interface matching problem, interface modifiers have limited effect on improving battery stability, and most products rely on imports. The preparation technology is monopolized by a few institutions, resulting in high production costs, which seriously restricts the independent development of my country's perovskite / crystalline silicon tandem battery industry.

[0004] Therefore, developing a multifunctional, synergistic, highly adaptable, and low-cost composite additive is of great practical significance. Summary of the Invention

[0005] This invention proposes a multifunctional composite additive for perovskite / crystalline silicon tandem solar cells, which solves one or more of the defects of existing perovskite thin films, thereby meeting the application requirements of improving the stability of perovskite / crystalline silicon tandem solar cells.

[0006] The technical solution of this invention is implemented as follows: The first aspect of the present invention is to provide a multifunctional composite additive for perovskite / crystalline silicon tandem solar cells, comprising, by mass percentage: 30-50% organic amine, 20-40% thiol-containing organophosphonate, and 10-30% fluorinated alkyl silane derivative; wherein the organic amine is an organic amine compound containing amino and carboxyl bifunctional groups.

[0007] Furthermore, the organic amine has the molecular formula R1-NH2-(CH2)n-COOH, where R1 is a C1-C4 alkyl group and n is an integer from 2 to 4.

[0008] Preferably, the organic amine is selected from one or more of 3-aminopropionic acid, 4-aminobutyric acid, and 2-aminobutyric acid.

[0009] Furthermore, the fluorinated alkyl silane derivative contains -C m F 2m-1 The group is a -Si(OR2)3 group, where m is an integer from 3 to 6, and R2 is a C1-C2 alkyl group.

[0010] Furthermore, the fluorinated alkyl silane derivative is selected from perfluorooctyltriethoxysilane and / or perfluorohexyltrimethoxysilane.

[0011] Furthermore, the thiol-containing organophosphonate is selected from 3-mercaptopropylphosphonic acid and / or 2-mercaptoethylphosphonic acid.

[0012] A second aspect of the present invention is to provide a method for preparing the multifunctional composite additive described in the first aspect, wherein the components are mixed and then filtered under a protective atmosphere to obtain the multifunctional composite additive.

[0013] A third aspect of the invention is to provide the application of the multifunctional composite additive described in the first aspect in perovskite / crystalline silicon tandem solar cells.

[0014] A fourth aspect of the present invention is to provide a perovskite / crystalline silicon tandem photovoltaic module, which is assembled from a perovskite thin film and crystalline silicon, characterized in that the perovskite thin film is obtained by coating and annealing a precursor solution containing a composite additive; the composite additive is any one of the multifunctional composite additives described in 1-5, and the amount added is 0.1-2% of the mass of the precursor solution.

[0015] Furthermore, the coating is spin coating, with a rotation speed of 3000-5000 rpm and a spin coating time of 30-60 s; And / or, the annealing parameters are: preheating at 80-100℃ for 1-2 min, and then holding at 150-180℃ for 10-20 min.

[0016] Furthermore, the solute in the perovskite precursor solution is selected from one or more of formamidinium lead iodine, formamidinium cesium lead iodine, and formamidinium rubidium lead iodine, and the solvent is a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide; preferably, the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is (4-6):1.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The composite additive of this invention is formulated by rationally selecting components with specific functional groups. The crystallization regulating components, interface modification components and stability enhancing components work synergistically to solve the three major technical bottlenecks of poor perovskite layer crystal quality, severe interface charge recombination and insufficient stability. Compared with traditional single-function additives, it has a more significant effect on improving battery performance.

[0018] The composite additive described in this invention has a component structure designed specifically for the process requirements of perovskite / crystalline silicon tandem solar cells. It has good compatibility with perovskite precursor solutions, crystalline silicon substrates, and transport layers, and can be directly applied to existing tandem solar cell production processes without significant adjustments to equipment parameters. When applied to perovskite / crystalline silicon tandem solar cells, the laboratory conversion efficiency can be increased to over 34%, and the degradation rate is less than 8% after 1000 hours of outdoor irradiation testing, meeting the core indicator requirements for industrial applications and demonstrating significant application prospects. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention proposes a multifunctional composite additive for perovskite / crystalline silicon tandem solar cells. Through the synergistic effect of multiple components, it simultaneously achieves perovskite crystallization regulation, interface modification, and stability enhancement, thereby improving the conversion efficiency and long-term stability of the tandem solar cells. Specifically, the multifunctional composite additive comprises, by mass percentage: 30-50% crystallization regulation component, 20-40% interface modification component, and 10-30% stability enhancement component. The specific components are as follows: The crystallization regulating component is an organic amine compound containing both amino and carboxyl bifunctional groups, with the general molecular formula R1-NH2-(CH2)n-COOH, where R1 is a C1-C4 alkyl group and n is an integer from 2 to 4. This type of compound optimizes the crystal morphology and grain size of perovskite films and reduces the defect state density to 102 through coordination between the amino group and perovskite ions, and the carboxyl group participates in crystal growth regulation. 15 cm -3 the following; The interface modification component is a thiol-containing organophosphonate, whose molecular structure contains -PO(OH)2 and -SH groups. The thiol group can effectively passivate interface defects, reduce the interfacial charge recombination rate, and improve the interfacial charge transfer efficiency to over 90%. The stability-enhancing component is a fluorinated alkyl silane derivative with a molecular structure containing -C.m F 2m-1 The alkyl group and the -Si(OR2)3 group, where m is an integer from 3 to 6, and R2 is a C1-C2 alkyl group. Fluoroalkyl groups have excellent hydrophobicity, which can improve the damp heat stability of the battery; silane groups can form a cross-linked network with the interface, enhancing the encapsulation effect and improving the light irradiation stability.

[0021] In some preferred embodiments, the crystallization regulating component is selected from one or more of 3-aminopropionic acid, 4-aminobutyric acid, and 2-aminobutyric acid; the interface modifying component is selected from one or more of 3-mercaptopropylphosphonic acid and 2-mercaptoethylphosphonic acid. The stability enhancing component is selected from one or more of perfluoro(tetrazolium)octyltriethoxysilane and perfluoro(nonafluoro)hexyltrimethoxysilane.

[0022] In a preferred embodiment, the functional components described above can be selected from commercially available reagents or prepared in-house. When prepared in-house, the following preparation method is used: 1) Synthesis of crystallization-regulating components: Aliphatic diamines and halocarboxylic acids were added to a reaction vessel at a molar ratio of 1:1.05-1.2, using ethanol as a solvent, and the mixture was stirred at 40-60℃ for 4-8 hours. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was recrystallized 2-3 times using an ethanol-water mixed solvent (volume ratio 3:1-5:1) to obtain crystallization-regulating components with a purity ≥99.5%.

[0023] 2) Synthesis of the interface-modifying component: Mercaptool and phosphorus trichloride were added to anhydrous diethyl ether at a molar ratio of 1:0.35-0.4 and reacted at 0-5°C in the dark for 2-4 hours. After the reaction was complete, deionized water was slowly added dropwise for hydrolysis for 30-60 minutes, the pH was adjusted to 2-3, and the mixture was extracted three times with ethyl acetate. The organic phases were combined, concentrated by rotary evaporation, and purified by column chromatography to obtain the interface-modifying component.

[0024] In a preferred embodiment, the preparation method of the above-mentioned multifunctional composite additive is as follows: the crystallization regulating component, the interface modifying component, and the stability enhancing component are added to a mixing container in proportion, stirred and mixed at 25-35°C for 30-60 minutes, protected by nitrogen gas, and filtered through a 0.22μm organic phase filter membrane to remove mechanical impurities, thereby obtaining a multifunctional composite additive with a product purity ≥99.9%.

[0025] The present invention also proposes the application of the above-mentioned multifunctional composite additive in perovskite / crystalline silicon tandem solar cells. Specifically, the multifunctional composite additive is added to the precursor solution at 0.1-2% of the mass of the perovskite precursor solution, stirred evenly, and then coated onto the surface of the crystalline silicon substrate or transport layer using a spin coating process. After annealing, a perovskite thin film is prepared, and then assembled to form a perovskite / crystalline silicon tandem photovoltaic module to form a cell.

[0026] In the above applications, the multifunctional composite additive can effectively improve battery conversion efficiency and stability. In some specific embodiments, the battery laboratory conversion efficiency can be increased to more than 34%, and the decay rate is less than 8% after 1000 hours of outdoor irradiation test.

[0027] In a preferred embodiment, the coating is spin coating at a speed of 3000-5000 rpm for a spin coating time of 30-60 s; the annealing parameters are: preheating at 80-100℃ for 1-2 min, and then holding at 150-180℃ for 10-20 min.

[0028] In a preferred embodiment, the solute of the perovskite precursor solution is selected from one or more of formamidinium lead iodine, formamidinium cesium lead iodine, and formamidinium rubidium lead iodine, and the solvent is a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide; preferably, the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is (4-6):1.

[0029] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0030] Example 1

[0031] A multifunctional composite additive for perovskite / crystalline silicon tandem solar cells is composed of the following components by mass percentage: 40% 3-aminopropionic acid (crystallization control component), 35% 3-mercaptopropylphosphonic acid (interface modification component), and 25% tridecafluorooctyltriethoxysilane (stability enhancement component).

[0032] The preparation method of this composite additive includes the following steps: (1) Synthesis of 3-aminopropionic acid: Ethylenediamine and 3-chloropropionic acid were added to a reaction vessel at a molar ratio of 1:1.1, and the mixture was stirred at 50°C for 6 hours using ethanol as the solvent. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was purified by recrystallization three times using an ethanol-water mixed solvent (volume ratio 4:1) to obtain 3-aminopropionic acid with a purity of 99.6%.

[0033] (2) Synthesis of 3-mercaptopropylphosphonic acid: 3-mercaptopropanol and phosphorus trichloride were added to anhydrous diethyl ether at a molar ratio of 1:0.38 and reacted at 2°C in the dark for 3 hours. Deionized water was slowly added dropwise for hydrolysis for 45 minutes, the pH was adjusted to 2.5, and the mixture was extracted three times with ethyl acetate. The organic phases were combined, concentrated by rotary evaporation, and purified by column chromatography to obtain 3-mercaptopropylphosphonic acid.

[0034] (3) Compounding of composite additives: 40g of 3-aminopropionic acid, 35g of 3-mercaptopropylphosphonic acid and 25g of tridecafluorooctyltriethoxysilane were added to a mixing container and stirred at 30°C for 45 minutes. Nitrogen gas was introduced for protection and the mixture was filtered through a 0.22μm organic phase filter membrane to obtain a multifunctional composite additive with a product purity of 99.92%.

[0035] In application, the composite additive is added to the formamidinium lead iodine precursor solution (solvent is N,N-dimethylformamide and dimethyl sulfoxide, volume ratio 5:1) at 0.8% of the mass of the perovskite precursor solution. After stirring evenly, it is spin-coated onto the surface of the crystalline silicon substrate at a speed of 4000 rpm. The perovskite film is prepared by preheating at 90°C for 1.5 minutes and then holding at 160°C for 15 minutes. The perovskite film is then assembled to form a perovskite / crystalline silicon tandem cell.

[0036] The battery was tested and found to have a conversion efficiency of 33.6%, with a degradation rate of 6.8% after 1000 hours of outdoor irradiation; the perovskite thin film defect state density was 8.2 × 10⁻⁶. 14 cm -3 The interface charge transfer efficiency is 92.3%.

[0037] Example 2

[0038] A multifunctional composite additive for perovskite / crystalline silicon tandem solar cells is composed of the following components by mass percentage: 35% 4-aminobutyric acid (crystallization control component), 40% 2-mercaptoethylphosphonic acid (interface modification component), and 25% perfluorohexyltrimethoxysilane (stability enhancement component).

[0039] The preparation method of this composite additive includes the following steps: (1) Synthesis of 4-aminobutyric acid: Propylene diamine and 4-chlorobutyric acid were added to a reaction vessel at a molar ratio of 1:1.08, and the mixture was stirred at 45°C for 7 hours using ethanol as the solvent. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was purified twice by recrystallization using an ethanol-water mixed solvent (volume ratio 3:1) to obtain 4-aminobutyric acid with a purity of 99.5%.

[0040] (2) Synthesis of 2-mercaptoethylphosphonic acid: 2-mercaptoethanol and phosphorus trichloride were added to anhydrous diethyl ether at a molar ratio of 1:0.35 and reacted at 0°C in the dark for 4 hours. Deionized water was slowly added dropwise for hydrolysis for 60 minutes, the pH was adjusted to 2, and the mixture was extracted three times with ethyl acetate. The organic phases were combined, concentrated by rotary evaporation, and purified by column chromatography to obtain 2-mercaptoethylphosphonic acid.

[0041] (3) Compounding of composite additives: 35g of 4-aminobutyric acid, 40g of 2-mercaptoethylphosphonic acid and 25g of perfluorohexyltrimethoxysilane were added to a mixing container and stirred at 25°C for 60 minutes. Nitrogen gas was introduced for protection and the mixture was filtered through a 0.22μm organic phase filter membrane to obtain a multifunctional composite additive with a product purity of 99.90%.

[0042] In application, the composite additive is added to the formamidinium lead iodine precursor solution (solvent is N,N-dimethylformamide and dimethyl sulfoxide, volume ratio 6:1) at 1.2% of the mass of the perovskite precursor solution. After stirring evenly, it is spin-coated onto the surface of the transport layer at a speed of 3500 rpm. The perovskite film is prepared by preheating at 80°C for 2 minutes and then holding at 170°C for 12 minutes. The perovskite film is then assembled to form a perovskite / crystalline silicon tandem solar cell.

[0043] The battery was tested and found to have a conversion efficiency of 33.2%, with a degradation rate of 7.5% after 1000 hours of outdoor irradiation; the perovskite thin film defect state density was 9.5 × 10⁻⁶. 14 cm -3 The interface charge transfer efficiency is 91.1%.

[0044] Example 3

[0045] A multifunctional composite additive for perovskite / crystalline silicon tandem solar cells is composed of the following components by mass percentage: 50% 2-aminobutyric acid (crystallization control component), 20% 3-mercaptopropylphosphonic acid (interface modification component), and 30% tridecafluorooctyltriethoxysilane (stability enhancement component).

[0046] The preparation method of this composite additive includes the following steps: (1) Synthesis of 2-aminobutyric acid: Butanediamine and 2-chlorobutyric acid were added to a reaction vessel at a molar ratio of 1:1.2, and the mixture was stirred at 60°C for 4 hours using ethanol as the solvent. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was purified by recrystallization three times using an ethanol-water mixed solvent (volume ratio 5:1) to obtain 2-aminobutyric acid with a purity of 99.7%.

[0047] (2) Synthesis of 3-mercaptopropylphosphonic acid: 3-mercaptopropanol and phosphorus trichloride were added to anhydrous diethyl ether at a molar ratio of 1:0.4 and reacted at 5°C in the dark for 2 hours. Deionized water was slowly added dropwise for hydrolysis for 30 minutes, the pH was adjusted to 3, and the mixture was extracted three times with ethyl acetate. The organic phases were combined, concentrated by rotary evaporation, and purified by column chromatography to obtain 3-mercaptopropylphosphonic acid.

[0048] (3) Compounding of composite additives: 50g of 2-aminobutyric acid, 20g of 3-mercaptopropylphosphonic acid and 30g of tridecafluorooctyltriethoxysilane were added to a mixing container and stirred at 35°C for 30 minutes. Nitrogen gas was introduced for protection and the mixture was filtered through a 0.22μm organic phase filter membrane to obtain a multifunctional composite additive with a product purity of 99.93%.

[0049] In application, the composite additive is added to the formamidinium rubidium lead iodine precursor solution (solvent is N,N-dimethylformamide and dimethyl sulfoxide, volume ratio 4:1) at 0.5% of the mass of the perovskite precursor solution. After stirring evenly, it is spin-coated onto the surface of the crystalline silicon substrate at a speed of 5000 rpm. The perovskite film is prepared by preheating at 100°C for 1 minute and then holding at 150°C for 20 minutes. The perovskite film is then assembled to form a perovskite / crystalline silicon tandem cell.

[0050] The battery was tested and found to have a conversion efficiency of 33.1%, with a degradation rate of 7.2% after 1000 hours of outdoor irradiation; the defect state density of the perovskite thin film was 8.8 × 10⁻⁶. 14 cm -3 The interface charge transfer efficiency is 90.5%.

[0051] Example 4

[0052] A multifunctional composite additive for perovskite / crystalline silicon tandem solar cells is composed of the following components by mass percentage: 30% 3-aminopropionic acid (crystallization control component), 35% 2-mercaptoethylphosphonic acid (interface modification component), and 35% perfluorohexyltrimethoxysilane (stability enhancement component).

[0053] The preparation method of this composite additive includes the following steps: (1) Synthesis of 3-aminopropionic acid: Ethylenediamine and 3-chloropropionic acid were added to a reaction vessel at a molar ratio of 1:1.05, and the mixture was stirred at 42°C for 7.5 hours using ethanol as a solvent. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was purified twice by recrystallization using an ethanol-water mixed solvent (volume ratio 3.5:1) to obtain 3-aminopropionic acid with a purity of 99.5%.

[0054] (2) Synthesis of 2-mercaptoethylphosphonic acid: 2-mercaptoethanol and phosphorus trichloride were added to anhydrous diethyl ether at a molar ratio of 1:0.36 and reacted at 3°C ​​in the dark for 2.5 hours. Deionized water was slowly added dropwise for hydrolysis for 50 minutes, the pH was adjusted to 2.2, and the mixture was extracted three times with ethyl acetate. The organic phases were combined, concentrated by rotary evaporation, and purified by column chromatography to obtain 2-mercaptoethylphosphonic acid.

[0055] (3) Compounding of composite additives: 30g of 3-aminopropionic acid, 35g of 2-mercaptoethylphosphonic acid and 35g of perfluorohexyltrimethoxysilane were added to a mixing container and stirred at 28°C for 50 minutes. Nitrogen gas was introduced for protection and the mixture was filtered through a 0.22μm organic phase filter membrane to obtain a multifunctional composite additive with a product purity of 99.91%.

[0056] In application, the composite additive is added to the formamidinium lead iodine precursor solution (solvent is N,N-dimethylformamide and dimethyl sulfoxide, volume ratio 4.5:1) at 1.5% of the mass of the perovskite precursor solution. After stirring evenly, it is spin-coated onto the surface of the transport layer at a speed of 3800 rpm. The perovskite film is prepared by preheating at 85°C for 1.8 minutes and then holding at 165°C for 14 minutes. The perovskite film is then assembled to form a perovskite / crystalline silicon tandem solar cell.

[0057] The battery was tested and found to have a conversion efficiency of 33.3%, with a degradation rate of 7.3% after 1000 hours of outdoor irradiation; the defect state density of the perovskite thin film was 9.1 × 10⁻⁶. 14 cm -3 The interface charge transfer efficiency is 90.8%.

[0058] Example 5

[0059] A multifunctional composite additive for perovskite / crystalline silicon tandem solar cells is composed of the following components by mass percentage: 4-aminobutyric acid (crystallization control component) 45%, 3-mercaptopropylphosphonic acid (interface modification component) 30%, and tridecafluorooctyltriethoxysilane (stability enhancement component) 25%.

[0060] The preparation method of this composite additive includes the following steps: (1) Synthesis of 4-aminobutyric acid: Propylene diamine and 4-chlorobutyric acid were added to a reaction vessel at a molar ratio of 1:1.15, and the mixture was stirred at 55°C for 5 hours using ethanol as the solvent. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was purified by recrystallization three times using an ethanol-water mixed solvent (volume ratio 4.5:1) to obtain 4-aminobutyric acid with a purity of 99.6%.

[0061] (2) Synthesis of 3-mercaptopropylphosphonic acid: 3-mercaptopropanol and phosphorus trichloride were added to anhydrous diethyl ether at a molar ratio of 1:0.39 and reacted at 4°C in the dark for 3.5 hours. Deionized water was slowly added dropwise for hydrolysis for 40 minutes, the pH was adjusted to 2.8, and the mixture was extracted three times with ethyl acetate. The organic phases were combined, concentrated by rotary evaporation, and purified by column chromatography to obtain 3-mercaptopropylphosphonic acid.

[0062] (3) Compounding of composite additives: 45g of 4-aminobutyric acid, 30g of 3-mercaptopropylphosphonic acid and 25g of tridecafluorooctyltriethoxysilane were added to a mixing container and stirred at 32°C for 40 minutes. Nitrogen gas was introduced for protection and the mixture was filtered through a 0.22μm organic phase filter membrane to obtain a multifunctional composite additive with a product purity of 99.94%.

[0063] In application, the composite additive is added to the formamidinium lead iodine precursor solution (solvent is N,N-dimethylformamide and dimethyl sulfoxide, volume ratio 5.5:1) at 0.9% of the mass of the perovskite precursor solution. After stirring evenly, it is spin-coated onto the surface of the crystalline silicon substrate at a speed of 4200 rpm. The perovskite thin film is prepared by preheating at 95°C for 1.2 minutes and then holding at 175°C for 11 minutes. The perovskite / crystalline silicon tandem solar cell is then assembled.

[0064] The battery was tested and found to have a conversion efficiency of 33.5%, with a degradation rate of 6.9% after 1000 hours of outdoor irradiation; the perovskite thin film defect state density was 8.5 × 10⁻⁶. 14 cm -3 The interface charge transfer efficiency is 91.7%.

[0065] Comparative Example 1 (Crystallization regulating component lacking carboxyl functional group)

[0066] A comparative additive comprises the following components by weight percentage: 40% ethylamine (containing only amino groups, lacking carboxyl groups, as a substitute for crystallization control components), 35% 3-mercaptopropylphosphonic acid (interface modification component), and 25% tridecafluorooctyltriethoxysilane (stability enhancement component).

[0067] The preparation and application methods are the same as in Example 1, except that the crystallization control component is replaced with ethylamine.

[0068] The battery was tested and found to have a conversion efficiency of 29.2%, with a degradation rate of 12.5% ​​after 1000 hours of outdoor irradiation; the perovskite thin film defect state density was 4.7 × 10⁻⁶. 15 cm -3 The interface charge transfer efficiency is 83.6%.

[0069] Conclusion: When the carboxyl group is missing from the crystallization regulation component, it cannot effectively participate in the crystal growth regulation, and the defect state density of the perovskite film increases significantly, resulting in a 4.4 percentage point decrease in battery conversion efficiency and a significant reduction in stability. This proves that the synergy between the carboxyl and amino bifunctional groups is the key to optimizing crystallization quality.

[0070] Comparative Example 2 (interfacial modified component lacks thiol functional groups)

[0071] A comparative additive comprises the following components by weight percentage: 40% 3-aminopropionic acid (crystallization regulating component), 35% ethylphosphonic acid (containing only -PO (OH)2 group, lacking -SH group, as a substitute for interface modification component), and 25% tridecafluorooctyltriethoxysilane (stability enhancing component).

[0072] The preparation and application methods are the same as in Example 1, except that the interface modification component is replaced with ethylphosphonic acid.

[0073] The battery was tested and found to have a conversion efficiency of 29.1%, with a degradation rate of 13.2% after 1000 hours of outdoor irradiation; the defect state density of the perovskite thin film was 3.9 × 10⁻⁶. 15 cm -3 The interface charge transfer efficiency is 78.9%.

[0074] Conclusion: The absence of thiol groups in the interface modification components fails to effectively passivate interface defects, exacerbates interfacial charge recombination, significantly reduces charge transfer efficiency, decreases battery conversion efficiency by 4.5 percentage points, and markedly deteriorates stability, thus verifying the core role of thiol groups in interface defect passivation.

[0075] Comparative Example 3 (The stability-enhancing component lacks fluoroalkyl functional groups)

[0076] A comparative additive comprises the following components by weight percentage: 40% 3-aminopropionic acid (crystallization regulating component), 35% 3-mercaptopropylphosphonic acid (interface modification component), and 25% triethoxysilane (containing only -Si(OR2)3 groups, lacking perfluoroalkyl groups, and serving as a stability enhancing component).

[0077] The preparation and application methods are the same as in Example 1, except that the stability-enhancing component is replaced with triethoxysilane.

[0078] The battery was tested and found to have a conversion efficiency of 31.5%, with a degradation rate of 15.7% after 1000 hours of outdoor irradiation; the defect state density of the perovskite thin film was 2.3 × 10⁻⁶. 15 cm -3 The interface charge transfer efficiency is 85.2%.

[0079] Conclusion: After the absence of fluorinated alkyl groups in the stability-enhancing components, the battery's wet and heat stability was insufficient, and the degradation under long-term irradiation was accelerated, with the degradation rate increasing by 8.9 percentage points compared to Example 1. This confirms that the hydrophobicity of fluorinated alkyl groups is a key factor in improving the long-term stability of the battery.

[0080] Comparative Example 4 (containing only a single functional component)

[0081] A comparative additive containing only 100% 3-aminopropionic acid (a single crystallization regulating component).

[0082] The application method is the same as in Example 1, with the additive added to the formamidin lead iodine precursor solution at 0.8% of the mass of the perovskite precursor solution.

[0083] The battery was tested and found to have a conversion efficiency of 28.7%, with a degradation rate of 18.3% after 1000 hours of outdoor irradiation; the defect state density of the perovskite thin film was 5.6 × 10⁻⁶. 15 cm -3 The interface charge transfer efficiency was 75.4%. Conclusion: A single functional component cannot simultaneously solve the three major problems of crystallization, interface, and stability. The battery conversion efficiency decreased by 4.9 percentage points compared to Example 1, while the decay rate increased by 11.5 percentage points, fully demonstrating the necessity and superiority of the multi-component synergistic effect of this invention.

[0084] The performance data comparison of the above embodiments and comparative examples is shown in Table 1.

[0085] Table 1:

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multifunctional composite additive for perovskite / crystalline silicon tandem solar cells, characterized in that, The components, by mass percentage, include: 30-50% organic amines, 20-40% thiol-containing organophosphonates, and 10-30% fluorinated alkyl silane derivatives; wherein the organic amines are organic amine compounds containing bifunctional groups of amino and carboxyl groups.

2. The multifunctional composite additive as described in claim 1, characterized in that, The organic amine has the molecular formula R1-NH2-(CH2)n-COOH, where R1 is a C1-C4 alkyl group and n is an integer from 2 to 4.

3. The multifunctional composite additive as described in claim 1, characterized in that, The fluorinated alkyl silane derivatives contain -C m F 2m-1 The group is a -Si(OR2)3 group, m takes the value of an integer from 3 to 6, and R2 is a C1-C2 alkyl group.

4. The multifunctional composite additive as described in claim 1 or 3, characterized in that, The fluorinated alkyl silane derivatives are selected from perfluorooctyltriethoxysilane and / or perfluorohexyltrimethoxysilane.

5. The multifunctional composite additive as described in claim 1, characterized in that, The thiol-containing organophosphonate is selected from 3-mercaptopropylphosphonic acid and / or 2-mercaptoethylphosphonic acid.

6. A method for preparing the multifunctional composite additive according to any one of claims 1-5, characterized in that, After mixing all components, the mixture was filtered under a protective atmosphere to obtain a multifunctional composite additive.

7. The application of the multifunctional composite additive according to any one of claims 1-5 in perovskite / crystalline silicon tandem solar cells.

8. A perovskite / crystalline silicon tandem photovoltaic module, assembled from a perovskite thin film and crystalline silicon, characterized in that, The perovskite film is obtained by coating and annealing a precursor solution containing a composite additive; the composite additive is any one of the multifunctional composite additives described in 1-5, and the amount added is 0.1-2% of the mass of the precursor solution.

9. The perovskite / crystalline silicon tandem photovoltaic module according to claim 8, characterized in that, The coating is a spin coating, with a rotation speed of 3000-5000 rpm and a spin coating time of 30-60 s; And / or, the annealing parameters are: preheating at 80-100℃ for 1-2 min, and then holding at 150-180℃ for 10-20 min.

10. The perovskite / crystalline silicon tandem photovoltaic module according to claim 8, characterized in that, The solute in the perovskite precursor solution is selected from one or more of formamidinium lead iodine, formamidinium cesium lead iodine, and formamidinium rubidium lead iodine, and the solvent is a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide.

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