Composition Regulation Of Mixed Cationic Tin Halide Perovskite Solar Cells

With the development of society,energy consumption is intensifying and there is an urgent need to find renewable and clean energy sources that can replace non-renewable fossil energy sources such as coal and oil.Solar energy is an ideal renewable and clean energy source,and solar cells are important energy conversion devices.Lead halide perovskite solar cells have excellent photovoltaic performance,and the solar conversion efficiency has rapidly increased from the initial 3.8%to over 25%in recent years,making them a possible solution for low-cost photovoltaic power generation.Due to the toxicity of lead element,there is a need to find low toxicity halide perovskite materials to replace lead halide perovskite materials.Tin halide perovskite materials show excellent semiconductor properties such as more desirable band gap,large absorption range,high carrier mobility,and low exciton binding energy,and are currently attracting much attention.In this paper,the high-efficiency hybrid cationic perovskite solar cell devices were prepared by tuning the composition of perovskite materials with tin halide perovskite solar cells as the research object.The main research contents are as follows.1.In the CH（NH₂）₂SnI₃（FASnI₃）perovskite system,the effect of thiourea additive on the performance of perovskite thin films was investigated Compared with the perovskite thin films without thiourea addition,thiourea additive can enhance the crystallinity of perovskite thin films and reduce the defect density,thus reducing the non-radiative compounding process in the perovskite thin films.By assembling FASnI3 perovskite solar cells,it was found that the addition of thiourea additive could increase the device efficiency from 4.38%to 5.34%and showed good reproducibility.Further tests show that the addition of thiourea effectively reduces the carrier complexation rate of the perovskite solar cell,which is conducive to improving the interfacial charge collection efficiency,thus enhancing the overall device performance.2.The introduction of NH₂NH₃Br（HYBr）to partially replace CH（NH₂）₂I（FAI）can modulate the crystal structure tolerance factor of the perovskite material and improve the stability of the perovskite crystal structure.HYxFA1-xSnI3-xBrx mixed cationic perovskite films were prepared by compositional modulation of FASnI3 perovskite,and the effect of HYBr replacement ratio was investigated.The results showed that the crystallinity of the perovskite films was improved,pinhole was reduced,and the size of perovskite grains was increased after 10%replacement of FAI by HYBr,which was beneficial to reduce the internal defects of the devices.Meanwhile,the reducing property of HYBr is beneficial to inhibit the oxidation of divalent Sn2+ions in HYxFA1-xSnI3-xBrx films,reduce the Sn4+content in the perovskite films,and reduce the film defects caused by oxidation.In addition,HY+ions are Lewis basic and can provide lone pair electrons to form coordination with SnI2,which has a certain passivating effect on the defects in the perovskite films.The assembly of perovskite solar cells with HYxFA1-xSnI3-xBrx as the light-absorbing layer shows that the solar conversion efficiency of 10%FAI devices can be increased from 5.62%to 10.31%by replacing HYBr.The optical stability of the device has also been improved.