Superior efficiency achievement for FAPbI3-perovskite thin film solar cell by optimization with response surface methodology technique and partial replacement of Pb by Sn

This study is focused on the partial replacement of Pb by Sn in FAPb1-xSnxI3thin films. In addition, preparation and optimization of deposition parameters of FAPbI3-perovskite solar cell synthesis using parametric study as well as response surface methodology (RSM) is focused. All the major quality control parameters (ratio of PbI2:FAI (3:4-5:4), rotational speed (2500-3500 rpm) of spin coater, and annealing temperature (100-160 °C) are considered for optimization. The parametric study is focused on the optimization of thickness (nm) of FAPbI3 layer. The value of thickness of FAPbI3 film at parametric optimum condition was 463 nm and the efficiency of corresponding device was 10.58%. Furthermore, to achieve further specific optimum condition, RSM was applied. Optimum condition using RSM were achieved to be 417 nm thickness leading to enhanced efficiency of 12.81%. Additionally, replacement of Pb by Sn (with SnI2) could further lead to improved efficiency and can make the cell less toxic. For Pb replacement by Sn study, molar ratio of PbI2:SnI2 was optimized to prepare FA+ Pb1-xSnxI3−films. The optimum film was FAPb0.5Sn0.5I3, which led to enhanced efficiency of 14.09%. The superior enhancement after Pb replacement is highly encouraging, as it leads to less toxic and highly efficient solar cells at the same time.