Numerical Simulation and Optimization of Highly Stable and Efficient Lead-Free Perovskite FA(1−x)Cs(x)SnI(3)-Based Solar Cells Using SCAPS

Formamidinium tin iodide (FASnI(3))-based perovskite solar cells (PSCs) have achieved significant progress in the past several years. However, these devices still suffer from low power conversion efficiency ([Formula: see text]) and poor stability. Recently, Cesium (Cs)-doped Formamidinium tin iodide ([Formula: see text] showed enhanced air, thermal, and illumination stability of PSCs. Hence, in this work, [Formula: see text] PSCs have been rigorously studied and compared to pure FASnI(3) PSCs using a solar cell capacitance simulator (SCAPS) for the first time. The aim was to replace the conventional electron transport layer (ETL) TiO(2) that reduces PSC stability under solar irradiation. Therefore, [Formula: see text] PSCs with different Cs contents were analyzed with TiO(2) and stable ZnOS as the ETLs. Perovskite light absorber parameters including Cs content, defect density, doping concentration and thickness, and the defect density at the interface were tuned to optimize the photovoltaic performance of the PSCs. The simulation results showed that the device efficiency was strongly governed by the ETL material, Cs content in the perovskite and its defect density. All the simulated devices with ZnOS ETL exhibited [Formula: see text] exceeding [Formula: see text] when the defect density of the absorber layer was below [Formula: see text] , and deteriorated drastically at higher values. The optimized structure with [Formula: see text] as light absorber and ZnOS as ETL showed the highest [Formula: see text] of [Formula: see text] with an open circuit voltage [Formula: see text] of [Formula: see text] , short-circuit current density [Formula: see text] of [Formula: see text] , and fill factor FF of [Formula: see text]. Our results obtained from the first numerical simulation on Cs-doped FASnI(3) could greatly increase its potential for practical production.