The Investigation Of Tin Halide Perovskite Solar Cells

Organic-inorganic hybrid halide perovskites have attracted great attention as a new type of photovoltaic materials.However,lead?Pb?perovskite solar cells?PSCs?would cause envirnomental pollution in future large-scale applications.Therefore,it is imperative to find environmentally-friendly metals to replace lead.Although tin?Sn?halide perovskites can be regarded as a valid alternative to lead perovskites,their poor stability and lower conversion efficiency hinder the substitution of Sn for Pb.In the work one,a fully tin-based,mixed-organic-cation perovskite absorber?FA?_x?MA?_1-xSnI₃?FA = NH₂CH = NH₂⁺,MA = CH₃NH₃⁺?for lead-free perovskite solar cells?PSCs?is presented.As FA increases its bandgap reduce from 1.37 eV to 1.27 eV.By optimizing the ratio of FA and MA cations.a maximum power conversion efficiency?PCE?of 2.41%is achieved for the?FA?_0.75?MA?_0.25SnI₃-based device along with a high open-circuit voltage of 0.40 V.which originates from improved perovskite film morphology and the reduction of internal charge traps in the deviceCompared to lead-based perovskite solar cells,the performance of the lead-based devices is very low,which is attributed to the poor morphology and high LUMO level.In order to improve the morphology and loweren the LUMO level,some lead thiocyanate is introduced to the tin-based perovskite solar cells to improve morphology and lower LUMO leveal.Highly uniform and pinhole-free perovskite films were prepared by the introduction of a small amount of lead thiocyanate in precursor solutions.The CH₃NH₃SnI₃?MASnI₃?films with Pb?SCN?2 additive show an absorption edge of 950 nm.Besides,lead ions can depress the LUMO energy level of Sn-based perovskite materials,which leads an increase in the open-circuit voltages of PSCs.Consequently,the enhanced performance was achieved for the PSCs based on MASnl₃ with a fill factor of 66%,open circuit voltage of 0.54 V and maximums power conversion efficiency of 6.03%.