Optimization of ETL layers for CH3NH3SnBr3 -perovskite solar cells through numerical analysis

Tin based perovskite (CH 3 NH 3 SnBr 3 ) solar cells have become popular due to eco-friendly nature, improved energy conversion efficiency, low cost and easy fabrication process. In this study, a numerical modelling (SCAPS-1D) is utilized to optimize CH 3 NH 3 SnBr 3 based perovskite solar cell devices incorporating four Electron transport layers (ETL) materials (C 60 , PCBM, SnS 2 , and ZnSe). Systematical investigation on absorber defect density, ETL layer thickness, and doping profiles was conducted to enhance device performance. The observation indicated that, FTO/SnS 2 / CH 3 NH 3 SnBr 3 /Cu 2 O/Au and FTO/ZnSe/ CH 3 NH 3 SnBr 3 /Cu 2 O/Au both the structures achieve a power conversion efficiency of 27.94 %. The employment of SnS 2 develops an open-circuit voltage (V oc ) of 1.0058 V, a short-circuit current density (J sc ) of 34.005067 mA/cm 2 , and a fill factor (FF) of 81.67 %. On the other hand, ZnSe as ETL develops V oc of 1.0059 V, J sc of 34.002106 mA/cm 2 , and an FF of 81.68 %. Subsequent stability analyses under varying temperatures, resistances, and recombination mechanisms confirm the robustness of both optimized structures. These results underscore the importance of strategic ETL selection in enhancing not only the efficiency but also the long-term stability of CH 3 NH 3 SnBr 3 -based perovskite solar cells.