Numerical Simulation and Optimization of Highly Stable and Efficient Lead-Free Perovskite FA1-xCsxSnI3-Based Solar Cells Using SCAPS.

Abstract

Formamidinium tin iodide (FASnI3)-based perovskite solar cells (PSCs) have achieved significant progress in the past several years. However, these devices still suffer from low power conversion efficiency () and poor stability. Recently, Cesium (Cs)-doped Formamidinium tin iodide ( showed enhanced air, thermal, and illumination stability of PSCs. Hence, in this work, PSCs have been rigorously studied and compared to pure FASnI3 PSCs using a solar cell capacitance simulator (SCAPS) for the first time. The aim was to replace the conventional electron transport layer (ETL) TiO2 that reduces PSC stability under solar irradiation. Therefore, PSCs with different Cs contents were analyzed with TiO2 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 exceeding when the defect density of the absorber layer was below , and deteriorated drastically at higher values. The optimized structure with as light absorber and ZnOS as ETL showed the highest of with an open circuit voltage of , short-circuit current density of , and fill factor FF of . Our results obtained from the first numerical simulation on Cs-doped FASnI3 could greatly increase its potential for practical production.