FASnI₃ and FAMASnGeI₃ as absorbers with TCOs as ETLs for eco-friendly high-performance perovskite solar cells

This work presents a study on novel lead-free Perovskite Solar Cells (PSCs) based on new lead-free absorbers (FASnI₃ and FAMASnGeI₃) that have been designed, optimized and analyzed through comparison with other experimental works in literature for high-performance, eco-friendly and cost-effective solar photovoltaic devices by working upon materials, interfaces and device structures. The work focuses on maximizing PSC efficiency and eliminating Sulphur and Lead-based elements. PSCs have been designed with lead-based absorbers (MAPbI₃) and lead-free absorbers (FASnI₃ and FAMASnGeI₃) having Electron Transport Layer (ETL) material using Transparent conducting oxides (TCOs) ( TiO₂, ZnO, WO3, and IGZO) and sulphides ( ZnS, WS₂, CdS, and CdZnS). The input parameters, such as thickness, bandgap, and interface defect variation for ETL and absorber materials, have been considered for device analysis. The optimized PSC structures' electric current flow and thermal diffusivity have been further tuned to get optimum results. The performance evaluation of the PSCs has been conducted based on the critical output performance of the parameters, namely Power Conversion Efficiency (PCE), open circuit voltage (V_OC), Fill Factor (FF) and current density (J_SC). Among lead-based PSCs, the PCBM-based PSC with the structure PCBM/MAPbI₃/Spiro MeOTAD exhibited tunable power conversion efficiency (PCE) of 21.03%, with J_SC of 23.40 mA/cm², V_OC of 1.02 V, and FF of 83.74%. Among the lead-free PSCs, the device structure PCBM/FAMASnGeI₃/PEDOT:PSS, optimized by adjusting the ETL (PCBM) and absorber (FAMASnGeI₃), demonstrated a tunable PCE of 33.42%, with J_SC: 28.61 mA/cm², V_OC: 1.358 V with FF of 82.86%. The maximum achieved PCE for the lead-free and lead-based PSCs discussed in this study has been 33.42% and 31.21%, respectively. This work provides valuable insights into selecting suitable eco-friendly absorber materials, the optimal high-performance design, and environmentally friendly PSCs for upcoming research developments. The results presented in this paper can guide researchers in identifying the most suitable materials and optimizing the development of highly effective, eco-friendly photovoltaic solar cells.