A lead-free tin-based perovskite solar cell interface modifier and a preparation method thereof

Abstract

This invention relates to the field of battery interface modifier technology, specifically a lead-free tin-based perovskite solar cell interface modifier; it comprises maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium tetrafluoroborate, and aminated graphene oxide; the modifier combines the modified copolymer with a dual ionic liquid to construct a protective layer that combines ionic conductivity and hydrophobicity with antioxidant properties; its core is to utilize the modified copolymer to improve the chemical compatibility with the perovskite absorber layer, and to compound two ionic liquids to provide efficient transport channels and enhance hydrophobicity respectively; this invention overcomes the defects of poor compatibility of traditional polymers and low protection efficiency of single materials, and achieves the best balance between ionic conductivity and interfacial hydrophobicity through multi-component synergy, effectively improving the overall protection performance.

Description

Technical Field

[0001] This invention relates to the field of battery interface modifier technology, specifically to a lead-free tin-based perovskite solar cell interface modifier and its preparation method. Background Technology

[0002] As lead-free tin-based perovskite solar cell technology develops rapidly, the complexity of the device interface structure increases significantly. This complexity brings many challenges, especially in terms of the comprehensive improvement of interface environment stability and photoelectric conversion efficiency.

[0003] Currently, the interfacial properties between the perovskite absorber layer and the electrode layer are generally improved by introducing single functional materials. Researchers construct interfacial modification layers using materials such as unmodified polymers or single ionic liquids. However, traditional interfacial modification methods rely on the physical or chemical properties of a single component, and need to address the inherent limitations of poor chemical compatibility and interfacial affinity between the polymer matrix and the perovskite layer. Although these methods can provide basic film-forming properties or ion conduction capabilities to a certain extent, they usually have low overall protection efficiency and may be difficult to achieve the optimal balance between ionic conductivity and interfacial hydrophobicity at the same time, resulting in an inability to effectively passivate surface defects and resist environmental water and oxygen erosion.

[0004] Therefore, how to synergistically optimize the hydrophobic protection, ion transport, and defect passivation properties of the interface, thereby comprehensively improving the photoelectric conversion efficiency and long-term environmental stability of tin-based perovskite solar cells, has become an urgent problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a lead-free tin-based perovskite solar cell interface modifier and its preparation method, so as to solve the problems mentioned in the background art. Specifically, the technical solution of this invention is as follows:

[0006] A lead-free tin-based perovskite solar cell interface modifier, the interface modifier comprising the following components:

[0007] Maleic anhydride modified polyvinylidene fluoride-hexafluoropropylene copolymer;

[0008] 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide;

[0009] 1-Butyl-3-methylimidazolium tetrafluoroborate;

[0010] And aminated graphene oxide.

[0011] Furthermore, the interface modifier comprises the following components by weight:

[0012] 70-80 parts maleic anhydride modified polyvinylidene fluoride-hexafluoropropylene copolymer;

[0013] 1-15 parts of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide;

[0014] 1-15 parts of 1-butyl-3-methylimidazolium tetrafluoroborate;

[0015] 4-7 parts of aminated graphene oxide.

[0016] Further, the weight ratio of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to 1-butyl-3-methylimidazolium tetrafluoroborate is 4:1 to 1:1.

[0017] Further, the weight ratio of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to 1-butyl-3-methylimidazolium tetrafluoroborate is 2:1 to 1:1.

[0018] Furthermore, the maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer is prepared by a method comprising the following steps:

[0019] Polyvinylidene fluoride-hexafluoropropylene copolymer was dissolved in a solvent, and maleic anhydride and a free radical initiator were added to carry out a grafting reaction. After precipitation, washing and drying, the product was obtained.

[0020] Furthermore, the aminated graphene oxide is prepared by a method comprising the following steps:

[0021] Graphene oxide is dispersed in water, an amination reagent is added to react, and the product is obtained after separation, washing, and drying.

[0022] A method for preparing an interface modifier for lead-free tin-based perovskite solar cells includes the following steps:

[0023] S1: Dissolve maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer in the first solvent to obtain solution A;

[0024] S2: Dissolve 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1-butyl-3-methylimidazolium tetrafluoroborate in a second solvent to obtain solution B;

[0025] S3: Aminated graphene oxide is dispersed in water to obtain dispersion C;

[0026] S4: Mix solution B with solution A, stir and react, then add dispersion C and stir to obtain the interface modifier precursor solution.

[0027] Further, the first solvent is one or more of N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide; the second solvent is one or more of isopropanol, ethanol, and acetonitrile.

[0028] A tin-based perovskite solar cell includes: a substrate, an electron transport layer, a perovskite absorber layer, an interface modification layer, and an electrode layer, wherein the interface modification layer is formed by the interface modifier described above or by an interface modifier prepared by the method described above.

[0029] Furthermore, the interface modification layer is located between the perovskite absorber layer and the electrode layer.

[0030] Compared with the prior art, the present invention has the following improvements and advantages:

[0031] 1. This invention uses maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer, which solves the problem of poor chemical compatibility between traditional polymers and perovskite absorber layers; at the same time, it combines 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1-butyl-3-methylimidazolium tetrafluoroborate to overcome the defect of low protection efficiency of single materials; the former provides a high-efficiency ion transport channel, and the latter enhances hydrophobicity and resistance to water and oxygen erosion. The three work together to achieve the best balance between ionic conductivity and interfacial hydrophobicity, effectively improving the overall protection performance;

[0032] 2. This invention overcomes the difficulty of simultaneously passivating surface defects and resisting environmental erosion by introducing aminated graphene oxide in combination with the above-mentioned modified copolymer, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylimidazolium tetrafluoroborate. Aminated graphene oxide significantly enhances the interfacial bonding strength, achieving efficient passivation of surface defects. The synergistic effect of each component constructs a dense physical barrier layer to prevent moisture intrusion, comprehensively improving the photoelectric conversion efficiency and long-term environmental stability of tin-based perovskite solar cells. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0034] Example 1:

[0035] This embodiment provides an interface modifier for tin-based perovskite solar cells and its preparation method; the interface modifier comprises, by weight, the following components:

[0036] The mixture consisted of 75 parts maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer, 12.5 parts 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 10 parts 1-butyl-3-methylimidazolium tetrafluoroborate, and 5 parts aminated graphene oxide. The weight ratio of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to 1-butyl-3-methylimidazolium tetrafluoroborate was 5:4, meeting the requirements for its compounding. At this ratio, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide provided ample and efficient ion transport channels, while an appropriate amount of 1-butyl-3-methylimidazolium tetrafluoroborate effectively optimized the interfacial microenvironment and significantly enhanced resistance to water and oxygen erosion.

[0037] The specific steps for preparing the interface modifier are as follows:

[0038] Preparation of modified polyvinylidene fluoride-hexafluoropropylene copolymer: 100 parts by weight of polyvinylidene fluoride-hexafluoropropylene copolymer raw material was dissolved in 500 parts by weight of N-methylpyrrolidone solvent, and stirred continuously at 70°C for 4 hours to ensure complete dissolution; 5 parts by weight of maleic anhydride and 0.1~0.5 parts by weight of azobisisobutyronitrile were added to the solution as initiators, the temperature of the reaction system was raised to 90°C, and the reaction was stirred at this temperature for 8 hours at a stirring speed of 500 rpm;

[0039] After the reaction is complete, slowly pour all the reaction solution into 5000 parts by weight of deionized water, and then... Stirring at a constant speed The polymer is fully precipitated; the precipitate is filtered and collected, and washed three times with deionized water. It is then dried in a vacuum drying oven at 60°C for 24 hours to obtain the desired modified polyvinylidene fluoride-hexafluoropropylene copolymer.

[0040] Preparation of aminated graphene oxide: Take 10 parts by weight of graphene oxide powder, disperse it in 200 parts by weight of deionized water, and perform ultrasonic treatment for 2 hours to ensure sufficient dispersion; add 20 parts by weight of ethylenediamine to the dispersion, stir and react at 60°C for 6 hours to complete the amination reaction; separate the reaction product by centrifugation, wash repeatedly with deionized water until the filtrate is neutral, and dry in a vacuum environment at 50°C for 12 hours to obtain aminated graphene oxide.

[0041] Preparation of polymer solution A: Dissolve 75 parts by weight of the modified polyvinylidene fluoride-hexafluoropropylene copolymer prepared above in 110 parts by weight of a mixed solvent of N,N-dimethylformamide / N-methylpyrrolidone / dimethyl sulfoxide, wherein the weight ratio of the three is as follows: The mixture was stirred continuously at 65℃ for 5 hours at a stirring speed of 500 rpm; after standing for 30 minutes to eliminate the bubbles generated during stirring, a homogeneous and transparent polymer solution A was obtained.

[0042] Preparation of biionic liquid dispersion B: 10 parts by weight of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 10 parts by weight of 1-butyl-3-methylimidazolium tetrafluoroborate were dissolved together in 50 parts by weight of acetonitrile solvent, stirred at room temperature for 1.5 h at a stirring speed of 800 rpm, and allowed to stand for 30 min to eliminate the bubbles generated during stirring, so as to obtain a homogeneous solution B;

[0043] Preparation of aminated graphene oxide nanodispersion C: 5 parts by weight of the above-mentioned aminated graphene oxide were dispersed in 35 parts by weight of deionized water and ultrasonically treated for 1.5 h to obtain a uniform dispersion C.

[0044] Preparation of the final interface modifier precursor solution: Under continuous stirring at 500 rpm, solution B was slowly added dropwise to solution A, with the addition time controlled within 10 min, and the mixture was stirred and mixed at 45 °C for 2.5 h to obtain a mixture D of polymer and diionic liquid; dispersion C was slowly added to the above mixture D, with the addition time controlled within 10 min, and the mixture was stirred and reacted at 55 °C for 3.5 h to finally obtain a homogeneous interface modifier composite precursor solution;

[0045] The lead-free tin-based perovskite solar cell device used in this embodiment has the following structure: indium tin oxide conductive substrate / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate electron transport layer / tin-based perovskite absorber layer / interface modification layer / aluminum electrode layer; except for the interface modification layer, all other layers can be prepared by conventional methods in the art; wherein the interface modification layer of the present invention is located between the tin-based perovskite absorber layer and the aluminum electrode layer, and its formation method is as follows:

[0046] Add 80 μL to 120 μL of interface modifier precursor solution to the prepared perovskite absorber layer, and spin coat the film using a spin coater, for example, spin coat at 3000 rpm for 40 s.

[0047] After spin coating, the device is placed on a 70°C hot stage and heated for 15 minutes to remove residual solvent and make the interface modification layer and perovskite layer tightly bonded. At this time, the average calibrated thickness of the interface modification layer after complete curing should be controlled in the range of 10nm to 15nm.

[0048] An aluminum electrode layer is prepared on the interface modification layer. The specific preparation steps are as follows: using a vacuum evaporation machine, the device is fixed on the evaporation turntable of the equipment, the gate is closed, and a vacuum is drawn until... Pa, aluminum was selected as the evaporation source. After preheating, the evaporation rate was stabilized at about 1.3 nm / 1 min. Then, the baffle was opened to start the evaporation process. The evaporation thickness was 1.200 μm. After the evaporation was completed, the equipment was turned off and the device was taken out after cooling.

[0049] Example 2:

[0050] This embodiment provides an interface modifier for tin-based perovskite solar cells and its preparation method; the interface modifier comprises, by weight, the following components:

[0051] The mixture consists of 70 parts maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer, 12 parts 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 12 parts 1-butyl-3-methylimidazolium tetrafluoroborate, and 6 parts aminated graphene oxide; wherein the weight ratio of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to 1-butyl-3-methylimidazolium tetrafluoroborate is approximately 1:1, which meets the requirements for its compounding.

[0052] At this ratio, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide provides ample and efficient ion transport channels, while an appropriate amount of 1-butyl-3-methylimidazolium tetrafluoroborate can effectively optimize the interfacial microenvironment and significantly enhance resistance to water and oxygen erosion.

[0053] The specific steps for preparing the interface modifier are as follows:

[0054] Preparation of modified polyvinylidene fluoride-hexafluoropropylene copolymer: 100 parts by weight of polyvinylidene fluoride-hexafluoropropylene copolymer raw material was dissolved in 500 parts by weight of N-methylpyrrolidone solvent, and stirred continuously at 70°C for 4 hours to ensure complete dissolution; 5 parts by weight of maleic anhydride and 0.1~0.5 parts by weight of azobisisobutyronitrile were added to the solution as initiators, the temperature of the reaction system was raised to 90°C, and the reaction was stirred at this temperature for 8 hours at a stirring speed of 500 rpm;

[0055] After the reaction is complete, slowly pour all the reaction solution into 5000 parts by weight of deionized water, and then... Stirring at a constant speed The polymer is fully precipitated; the precipitate is filtered and collected, and washed three times with deionized water. It is then dried in a vacuum drying oven at 60°C for 24 hours to obtain the desired modified polyvinylidene fluoride-hexafluoropropylene copolymer.

[0056] Preparation of aminated graphene oxide: Take 10 parts by weight of graphene oxide powder, disperse it in 200 parts by weight of deionized water, and perform ultrasonic treatment for 2 hours to ensure sufficient dispersion; add 20 parts by weight of ethylenediamine to the dispersion, stir and react at 60°C for 6 hours to complete the amination reaction; separate the reaction product by centrifugation, wash repeatedly with deionized water until the filtrate is neutral, and dry in a vacuum environment at 50°C for 12 hours to obtain aminated graphene oxide.

[0057] Preparation of polymer solution A: Dissolve 70 parts by weight of the modified polyvinylidene fluoride-hexafluoropropylene copolymer prepared above in 110 parts by weight of a mixed solvent of N,N-dimethylformamide / N-methylpyrrolidone / dimethyl sulfoxide, wherein the weight ratio of the three is as follows: The mixture was stirred continuously at 65℃ for 5 hours at a stirring speed of 500 rpm; after standing for 30 minutes to eliminate the bubbles generated during stirring, a homogeneous and transparent polymer solution A was obtained.

[0058] Preparation of biionic liquid dispersion B: 12 ​​parts by weight of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 12 parts by weight of 1-butyl-3-methylimidazolium tetrafluoroborate were dissolved together in 50 parts by weight of acetonitrile solvent, stirred at room temperature for 1.5 h at a stirring speed of 800 rpm, and allowed to stand for 30 min to eliminate the bubbles generated during stirring, so as to obtain a homogeneous solution B;

[0059] Preparation of aminated graphene oxide nanodispersion C: 6 parts by weight of the above aminated graphene oxide were dispersed in 35 parts by weight of deionized water and ultrasonically treated for 1.5 h to obtain a uniform dispersion C.

[0060] Preparation of the final interface modifier precursor solution: Under continuous stirring at 500 rpm, solution B was slowly added dropwise to solution A, with the addition time controlled within 10 min, and the mixture was stirred and mixed at 45 °C for 2.5 h to obtain a mixture D of polymer and diionic liquid; dispersion C was slowly added to the above mixture D, with the addition time controlled within 10 min, and the mixture was stirred and reacted at 55 °C for 3.5 h to finally obtain a homogeneous interface modifier composite precursor solution;

[0061] The lead-free tin-based perovskite solar cell device used in this embodiment has the following structure: indium tin oxide conductive substrate / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate electron transport layer / tin-based perovskite absorber layer / interface modification layer / aluminum electrode layer; except for the interface modification layer, all other layers can be prepared by conventional methods in the art; wherein the interface modification layer of the present invention is located between the tin-based perovskite absorber layer and the aluminum electrode layer, and its formation method is as follows:

[0062] Add 80 μL to 120 μL of interface modifier precursor solution to the prepared perovskite absorber layer, and spin coat the film using a spin coater, for example, spin coat at 3000 rpm for 40 s.

[0063] After spin coating, the device is placed on a 70°C hot stage and heated for 15 minutes to remove residual solvent and make the interface modification layer and perovskite layer tightly bonded. At this time, the average calibrated thickness of the interface modification layer after complete curing should be controlled in the range of 10nm to 15nm.

[0064] An aluminum electrode layer is prepared on the interface modification layer. The specific preparation steps are as follows: using a vacuum evaporation machine, the device is fixed on the evaporation turntable of the equipment, the gate is closed, and a vacuum is drawn until... Pa, aluminum was selected as the evaporation source. After preheating, the evaporation rate was stabilized at about 1.3 nm / 1 min. Then, the baffle was opened to start the evaporation process. The evaporation thickness was 1.200 μm. After the evaporation was completed, the equipment was turned off and the device was taken out after cooling.

[0065] In this embodiment, the formulation was enhanced by increasing the ratio of the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium tetrafluoroborate, and aminated graphene oxide; this adjustment aims to further synergistically improve the overall ionic conductivity and interfacial binding ability of the interface modifier.

[0066] Higher ionic liquid content is expected to provide better charge transport channels, while the introduction of more aminated graphene oxide is expected to enhance the two-dimensional network structure, thereby bringing more significant effects in water and oxygen barrier and multi-site defect passivation.

[0067] Example 3:

[0068] This embodiment provides an interface modifier for tin-based perovskite solar cells and its preparation method; the interface modifier comprises, by weight, the following components:

[0069] The mixture consists of 75 parts maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer, 12.5 parts 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 7.5 parts 1-butyl-3-methylimidazolium tetrafluoroborate, and 6 parts aminated graphene oxide; wherein the weight ratio of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to 1-butyl-3-methylimidazolium tetrafluoroborate is 5:3, which meets the requirements for its compounding.

[0070] At this ratio, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide provides ample and efficient ion transport channels, while an appropriate amount of 1-butyl-3-methylimidazolium tetrafluoroborate can effectively optimize the interfacial microenvironment and significantly enhance resistance to water and oxygen erosion.

[0071] The specific steps for preparing the interface modifier are as follows:

[0072] Preparation of modified polyvinylidene fluoride-hexafluoropropylene copolymer: 100 parts by weight of polyvinylidene fluoride-hexafluoropropylene copolymer raw material was dissolved in 500 parts by weight of N-methylpyrrolidone solvent, and stirred continuously at 70°C for 4 hours to ensure complete dissolution; 5 parts by weight of maleic anhydride and 0.1~0.5 parts by weight of azobisisobutyronitrile were added to the solution as initiators, the temperature of the reaction system was raised to 90°C, and the reaction was stirred at this temperature for 8 hours at a stirring speed of 500 rpm;

[0073] After the reaction is complete, slowly pour all the reaction solution into 5000 parts by weight of deionized water, and then... Stirring at a constant speed The polymer is fully precipitated; the precipitate is filtered and collected, and washed three times with deionized water. It is then dried in a vacuum drying oven at 60°C for 24 hours to obtain the desired modified polyvinylidene fluoride-hexafluoropropylene copolymer.

[0074] Preparation of amination-modified graphene oxide: Take 10 parts by weight of graphene oxide powder, disperse it in 200 parts by weight of deionized water, and perform ultrasonic treatment for 2 hours to ensure that it is fully dispersed; add 20 parts by weight of ethylenediamine to the dispersion, and stir the reaction at 60°C for 6 hours to complete the amination reaction.

[0075] The reaction products were separated by centrifugation and repeatedly washed with deionized water until the filtrate was neutral. The filtrate was then dried in a vacuum environment at 50°C for 12 hours to obtain aminated graphene oxide.

[0076] Preparation of polymer solution A: Dissolve 75 parts by weight of the modified polyvinylidene fluoride-hexafluoropropylene copolymer prepared above in 110 parts by weight of a mixed solvent of N,N-dimethylformamide / N-methylpyrrolidone / dimethyl sulfoxide, wherein the weight ratio of the three is as follows: The mixture was stirred continuously at 65℃ for 5 hours at a stirring speed of 500 rpm; after standing for 30 minutes to eliminate the bubbles generated during stirring, a homogeneous and transparent polymer solution A was obtained.

[0077] Preparation of biionic liquid dispersion B: 12.5 parts by weight of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 7.5 parts by weight of 1-butyl-3-methylimidazolium tetrafluoroborate were dissolved in 50 parts by weight of acetonitrile solvent, stirred at room temperature for 1.5 h at a stirring speed of 800 rpm, and allowed to stand for 30 min to eliminate bubbles generated during stirring, so as to obtain a homogeneous solution B;

[0078] Preparation of aminated graphene oxide nanodispersion C: 6 parts by weight of the above aminated graphene oxide were dispersed in 35 parts by weight of deionized water and ultrasonically treated for 1.5 h to obtain a uniform dispersion C.

[0079] Preparation of the final interface modifier precursor solution: Under continuous stirring at 500 rpm, solution B was slowly added dropwise to solution A, with the addition time controlled within 10 min, and the mixture was stirred and mixed at 45 °C for 2.5 h to obtain a mixture D of polymer and diionic liquid; dispersion C was slowly added to the above mixture D, with the addition time controlled within 10 min, and the mixture was stirred and reacted at 55 °C for 3.5 h to finally obtain a homogeneous interface modifier composite precursor solution;

[0080] The lead-free tin-based perovskite solar cell device used in this embodiment has the following structure: indium tin oxide conductive substrate / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate electron transport layer / tin-based perovskite absorber layer / interface modification layer / aluminum electrode layer; except for the interface modification layer, all other layers can be prepared by conventional methods in the art; wherein the interface modification layer of the present invention is located between the tin-based perovskite absorber layer and the aluminum electrode layer, and its formation method is as follows:

[0081] Add 80 μL to 120 μL of interface modifier precursor solution to the prepared perovskite absorber layer, and spin coat the film using a spin coater, for example, spin coat at 3000 rpm for 40 s.

[0082] After spin coating, the device is placed on a 70°C hot stage and heated for 15 minutes to remove residual solvent and make the interface modification layer and perovskite layer tightly bonded. At this time, the average calibrated thickness of the interface modification layer after complete curing should be controlled in the range of 10nm to 15nm.

[0083] An aluminum electrode layer is prepared on the interface modification layer. The specific preparation steps are as follows: using a vacuum evaporation machine, the device is fixed on the evaporation turntable of the equipment, the gate is closed, and a vacuum is drawn until... Pa, aluminum was selected as the evaporation source. After preheating, the evaporation rate was stabilized at about 1.3 nm / 1 min. Then, the baffle was opened to start the evaporation process. The evaporation thickness was 1.200 μm. After the evaporation was completed, the equipment was turned off and the device was taken out after cooling.

[0084] This embodiment further adjusts the ratio of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to 1-butyl-3-methylimidazolium tetrafluoroborate and amino-modified graphene oxide, increasing the proportion of bis(trifluoromethanesulfonyl)imide anion in the system, aiming to further optimize the hydrophobicity and chemical stability of the interface while maintaining high ionic conductivity.

[0085] Comparative Example 1: A method for preparing an interface modifier using only 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine ionic liquid

[0086] For comparative purposes, this comparative example was designed; the modifier formulation is as follows: 75 parts of modified polyvinylidene fluoride-hexafluoropropylene copolymer, 10 parts of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 5 parts of aminated graphene oxide.

[0087] Its preparation method is basically the same as that in Example 1. The core difference is that in the step of preparing the dual ionic liquid dispersion B, only 10 parts by weight of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide is dissolved in 25 parts by weight of acetonitrile, and 1-butyl-3-methylimidazolium tetrafluoroborate is not added. The rest of the steps remain unchanged.

[0088] A comparison of the performance with that of Example 1 above shows that although the single ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide can provide basic ionic conductivity, it lacks the additional hydrophobicity and enhanced chemical stability contributed by 1-butyl-3-methylimidazolium tetrafluoroborate. This indicates that the combination of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1-butyl-3-methylimidazolium tetrafluoroborate helps to improve ionic conductivity and interfacial stability.

[0089] Comparative Example 2: A method for preparing an interface modifier using only 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid

[0090] For comparative purposes, this comparative example was designed; the modifier formulation is as follows: 75 parts of modified polyvinylidene fluoride-hexafluoropropylene copolymer, 10 parts of 1-butyl-3-methylimidazolium tetrafluoroborate, and 5 parts of aminated graphene oxide.

[0091] Its preparation method is basically the same as that in Example 1. The core difference is that in the step of preparing the dual ionic liquid dispersion B, only 10 parts by weight of 1-butyl-3-methylimidazolium tetrafluoroborate is dissolved in 25 parts by weight of acetonitrile, and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide is not added. The rest of the steps remain unchanged.

[0092] By comparing the performance with that of Examples 1 and 2 above, it can be seen that the two ionic liquids complement each other, indicating that the combination of the two ionic liquids helps to improve ionic conductivity and interface stability.

[0093] Comparative Example 3: A method for preparing an interface modifier without aminated graphene oxide

[0094] For comparative purposes, this comparative example was designed; the modifier formulation consisted of 75 parts maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer, 10 parts 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 10 parts 1-butyl-3-methylimidazolium tetrafluoroborate; wherein the weight ratio of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to 1-butyl-3-methylimidazolium tetrafluoroborate was 1:1, which meets the requirements for its compounding.

[0095] Its preparation method is basically the same as that in Example 1, the core difference being that the steps of preparing aminated graphene oxide and preparing aminated graphene oxide nanodispersion C are omitted;

[0096] A comparison of the performance with that of Example 1 shows that the lack of aminated graphene oxide significantly reduces the interfacial bonding force and long-term stability between the interface modifier and the perovskite layer; indicating that aminated graphene oxide helps to build a stable interface.

[0097] Comparative Example 4: A method for preparing an interface modifier containing unmodified polyvinylidene fluoride-hexafluoropropylene copolymer

[0098] For comparative purposes, this comparative example was designed; the modifier formulation is as follows: 75 parts of unmodified polyvinylidene fluoride-hexafluoropropylene copolymer, 10 parts of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 10 parts of 1-butyl-3-methylimidazolium tetrafluoroborate, and 5 parts of aminated graphene oxide.

[0099] Its preparation method is basically the same as that in Example 1. The core difference is that in the raw material preparation stage, conventional original polyvinylidene fluoride-hexafluoropropylene copolymer resin is used directly without maleic anhydride modification, and the other steps remain unchanged.

[0100] A comparison of the performance with Example 1 shows that although the unmodified polyvinylidene fluoride-hexafluoropropylene copolymer retains good film-forming properties, its chemical compatibility and interfacial affinity with the perovskite layer are poor, resulting in more contact defects at the interface, and a decrease in interfacial bonding strength and overall device stability. This indicates that maleic anhydride chemical modification can improve the interfacial compatibility between the polymer matrix and the perovskite and the overall interfacial stability.

[0101] Test Experiment Design:

[0102] To further evaluate the effectiveness of the perovskite solar cell interface modifier of the present invention and verify its synergistic effect, the following series of standardized characterization tests were designed to demonstrate the performance differences between the examples and comparative examples.

[0103] 1. Interface contact angle test

[0104] Experimental objective: To evaluate the hydrophobic properties of interface modifiers;

[0105] Experimental method: Using a contact angle meter, water droplets were placed on the substrate coated with the modifier, and the contact angle was measured; five different locations were measured for each sample, and the average value was taken;

[0106] 2. Ionic conductivity test

[0107] Experimental objective: To evaluate the ion conductivity of interface modifiers;

[0108] Experimental methods: Electrochemical impedance spectroscopy was used for testing; the modifier was prepared into a thin film, sandwiched between two stainless steel electrodes, and tested at room temperature in the frequency range of 1 Hz to 1 MHz;

[0109] 3. Photoelectric conversion efficiency test

[0110] Experimental objective: To evaluate the efficiency of tin-based perovskite solar cells improved by interface modifiers;

[0111] Experimental Method: Using a solar simulator, tin-based perovskite solar cell samples modified with the modifier were connected to a test platform. Their current-voltage curves were measured, and the photoelectric conversion efficiency was calculated using the following formula after exporting the data. :

[0112]

[0113] in, To determine the standard incident light power density, a global solar spectrum with a standard atmospheric mass of 1.5 was used, and the light intensity was calibrated as follows: ; The open-circuit voltage is extracted from the current-voltage curve, in volts (V). Short-circuit current density, unit: , is the fill factor, a dimensionless parameter. In the formula... The bar represents multiplication, and the fraction bar represents division.

[0114] 4. Evaluation of Interface Defect Passivation Effect

[0115] Experimental objective: To evaluate the passivation ability of interface modifiers on perovskite surface defects;

[0116] Experimental methods: Steady-state photoluminescence and time-resolved photoluminescence were used for testing; an interface modifier was coated on a perovskite thin film, and the excitation wavelength was 450 nm. The photoluminescence intensity and carrier lifetime were measured; among them, the photoluminescence quenching efficiency was also measured. The calculation formula is:

[0117]

[0118] in, The fluorescence intensity of the perovskite film without the modification layer is shown. The fluorescence intensity of the perovskite film in the presence of an interface modification layer;

[0119] 5. Environmental stability test

[0120] Experimental objective: To evaluate the environmental protection effect of interface modifiers on perovskite solar cells;

[0121] Experimental method: The complete perovskite solar cells were aged in an environment with a relative humidity of 85% and a temperature of 85℃. The current-voltage curve was tested every 100 hours to measure the cell efficiency; the test duration was 1000 hours.

[0122] Test results:

[0123] Table 1: Performance Test Results

[0124] Note: The control group is a tin-based perovskite solar cell device without the polymer interface modifier involved in this invention. The baseline value of the photoluminescence quenching efficiency of the control group is 0.0%.

[0125] Based on systematic testing and comprehensive performance evaluation, the formulation and preparation process corresponding to Example 3 exhibit superior overall performance. The specific performance and underlying mechanism analysis are as follows:

[0126] 1. Regarding excellent hydrophobic properties

[0127] All embodiments of the present invention, covering Examples 1 to 3, consistently exhibited static water contact angle measurements exceeding 105°, a figure significantly higher than all comparative samples. This superior hydrophobicity is primarily attributed to the core dual-ionic-liquid synergistic system of the present invention. In this system, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1-butyl-3-methylimidazolium tetrafluoroborate complement each other, with 1-butyl-3-methylimidazolium tetrafluoroborate effectively enhancing the hydrophobic properties of the interfacial region. This high hydrophobicity is a crucial interfacial barrier layer against environmental moisture erosion, laying a solid foundation for significantly improving the environmental stability of perovskite solar cells.

[0128] 2. Regarding its excellent ion conductivity

[0129] In ionic conductivity testing, ionic conductivity It is obtained through electrochemical impedance spectroscopy, and its calculation formula is as follows:

[0130]

[0131] in, The thickness of the thin film is expressed in units of 1000 mm. ; The volume resistance is obtained by intersecting the impedance spectrum in the high-frequency region with the real axis, and the unit is . ; The effective area of ​​the test electrode, in units of Example 3 achieved an excellent value of 11.6 mS / cm, and Example 2 also reached 10.9 mS / cm, which is in stark contrast to Comparative Examples 1 and 2, clearly verifying the synergistic effect of the two-component compound.

[0132] This significant improvement stems from the synergistic mechanism of the two ionic liquids: 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide is mainly responsible for providing an efficient ion transport pathway, while 1-butyl-3-methylimidazolium tetrafluoroborate ensures the stability of the transport process by optimizing the interfacial microenvironment; the high ionic conductivity directly helps to reduce the interfacial resistance between the perovskite and the charge transport layer, thereby making a direct contribution to improving the fill factor and open-circuit voltage of the battery.

[0133] 3. Regarding excellent photoelectric conversion efficiency

[0134] All embodiments and comparative examples of the present invention have higher photoelectric conversion efficiencies than the control group, which indicates that all components in the interface modifier involved in the present invention can improve the performance of perovskite devices; among them, the best device is Example 3, which has a photoelectric conversion efficiency of 18.8%, which is significantly improved compared with the control group.

[0135] Furthermore, comparative examples using a single ionic liquid, without adding aminated graphene oxide, and without using maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer all showed varying degrees of decrease in photoelectric conversion efficiency. This indicates that the synergistic effect of the two ionic liquids and the suppression effect of aminated graphene oxide on interface defects in this invention are both significantly necessary for synergy and make important contributions to improving device performance.

[0136] 4. Regarding efficient interface defect passivation

[0137] In terms of optical characterization, all embodiments of the present invention exhibit strong interface defect passivation capabilities; their photoluminescence quenching efficiencies all exceed 81%, and the carrier lifetime measured by time-resolved photoluminescence is extended to more than 300 nanoseconds; these data are comprehensively superior to the control group.

[0138] The results show that the ternary composite system constructed from maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer, dual ionic liquid and aminated graphene oxide can generate diversified intermolecular interactions with perovskite through multiple functional groups such as carboxyl, amino and fluorine atoms, thereby efficiently passivating defect states such as surface dangling bonds and ion vacancies, and significantly suppressing nonradiative recombination channels that lead to efficiency loss.

[0139] 5. Regarding excellent environmental stability

[0140] In the most critical long-term environmental reliability test, Example 3 showed better performance; under the harsh conditions of 85°C high temperature and 85% relative humidity, after a continuous aging of up to 1000h, the perovskite solar cell using the modifier of this example still maintained an initial photoelectric conversion efficiency of up to 91.2%; this stability result is a comprehensive manifestation of the synergistic effect of the aforementioned advantages: excellent hydrophobicity prevents the direct invasion of water molecules;

[0141] Robust interface bonding and mechanical strength prevent the functional layers from peeling off under thermal stress; efficient defect passivation alleviates the generation and expansion of new defects under environmental stress; the three work together to improve the long-term operational stability of the device.

[0142] In summary, this invention, through multi-component material design to modify polymers, dual-ionic liquids, aminated graphene oxide, and an optimized stepwise preparation process, has successfully developed a multifunctional composite interface modifier for lead-free tin-based perovskite solar cells. This modifier achieves synergistic optimization and comprehensive improvement in multiple dimensions of performance, including hydrophobic protection, ion transport, defect passivation, mechanical enhancement, and environmental stability. This provides a practical and high-performance key interface material solution for constructing high-efficiency, long-life tin-based perovskite solar cells.

[0143] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A lead-free tin-based perovskite solar cell interface modifier, characterized in that, The interface modifier comprises the following components: Maleic anhydride modified polyvinylidene fluoride-hexafluoropropylene copolymer; 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; 1-Butyl-3-methylimidazolium tetrafluoroborate; And aminated graphene oxide.

2. The interface modifier according to claim 1, characterized in that, The interface modifier comprises the following components by weight: 70-80 parts maleic anhydride modified polyvinylidene fluoride-hexafluoropropylene copolymer; 1-15 parts of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; 1-15 parts of 1-butyl-3-methylimidazolium tetrafluoroborate; 4-7 parts of aminated graphene oxide.

3. The interface modifier according to claim 2, characterized in that, The weight ratio of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide to 1-butyl-3-methylimidazolium tetrafluoroborate is 4:1 to 1:

1.

4. The interface modifier according to claim 3, characterized in that, The weight ratio of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide to 1-butyl-3-methylimidazolium tetrafluoroborate is 2:1 to 1:

1.

5. The interface modifier according to claim 1, characterized in that, The maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer is prepared by a method comprising the following steps: Polyvinylidene fluoride-hexafluoropropylene copolymer was dissolved in a solvent, and maleic anhydride and a free radical initiator were added to carry out a grafting reaction. After precipitation, washing and drying, the product was obtained.

6. The interface modifier according to claim 1, characterized in that, The aminated graphene oxide is prepared by a method comprising the following steps: Graphene oxide is dispersed in water, an amination reagent is added to react, and the product is obtained after separation, washing, and drying.

7. A method for preparing the interface modifier according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Dissolve maleic anhydride-modified polyvinylidene fluoride-hexafluoropropylene copolymer in the first solvent to obtain solution A; S2: Dissolve 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and 1-butyl-3-methylimidazolium tetrafluoroborate in a second solvent to obtain solution B; S3: Aminated graphene oxide is dispersed in water to obtain dispersion C; S4: Mix solution B with solution A, stir and react, then add dispersion C and stir to obtain the interface modifier precursor solution.

8. The method according to claim 7, characterized in that, The first solvent is one or more of N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide; the second solvent is one or more of isopropanol, ethanol, and acetonitrile.

9. A tin-based perovskite solar cell, comprising a substrate, an electron transport layer, a perovskite absorber layer, an interface modification layer, and an electrode layer, characterized in that, The interface modification layer is formed by the interface modifier according to any one of claims 1-6 or the interface modifier prepared by the method according to any one of claims 7-8.

10. The tin-based perovskite solar cell according to claim 9, characterized in that, The interface modification layer is located between the perovskite absorber layer and the electrode layer.

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