Numerical optimization of lead-based and lead-free absorber materials for perovskite solar cell (PSC) architectures: A SCAPS-1D simulation

Due to the negative environmental impact, the usage of lead in perovskite solar cells has been a matter of concern. Moreover, a suitable replacement of Pb with similar optoelectrical properties is hard to find. MAPbI3 is the most common material that has been studied for solar PV applications. Compared to MAPbI3, Cs2TiBr6 and MASnI3 have been less studied. In this study, their potential in solar cell applications has been investigated. Titanium and tin are two materials that have been used in numerous studies as an alternative to Pb-based perovskite. However, the lack of optimization and combinations of electron transport layer (ETL) and hole transport layer (HTL) material choices leave a lot to be desired. In this study, two different perovskite absorber layers, Cs2TiBr6 and MASnI3, have been simulated, optimized, and compared with Pb-based MAPbI3, where La-doped BaSnO3 is used as ETL and CuSbS2 as HTL in identical cell architectures. La-doped BaSnO3 is well known for its high electron mobility and excellent optical properties, which makes it an ideal candidate for ETL. On the other hand, CuSbS2 has appropriate band alignment with perovskite materials and has a high absorption profile to be used as HTL. The simulations were analyzed by optimizing key parameters like absorber layer thickness, defect density, and temperature. The optimized device architecture reached the power conversion efficiencies (PCE) of 29.45% for MASnI3, followed by MAPbI3 (22.47%) and Cs2TiBr6 (21.96%). The result indicates that high performance lead-free perovskite cells are very much possible through proper material selection and optimization.