Numerical optimization of TiO2/SnO2 bilayer electron transport layers for enhanced perovskite solar cell performance

To improve charge extraction and address UV-induced degradation in perovskite solar cells, we propose and numerically evaluate a TiO2/SnO2 bilayer electron transport layer (ETL) architecture. Using physics-based simulation, we systematically analyze the influence of individual and combined ETL thicknesses on key parameters. The results identify an optimal configuration of 100 nm TiO2 and 20 nm SnO2, which minimizes interfacial recombination and enhances electron transport. Furthermore, CH3NH3SnI3 is employed as a lead-free absorber layer. Simulation results demonstrate a notable efficiency improvement upto 20.80%. The experimental results verified that the bi-layer Sn-based perovskite can achieve a conversion efficiency of 10.3%. This study highlights the potential of simulation-guided design in optimizing multilayer ETL structures and advancing environmentally friendly, high-efficiency perovskite photovoltaics.