Tailored MoO3 hole transport layer for performance enhancement in lead-free hybrid tandem perovskite solar cell

This study reports the design and optimization of a two-terminal tandem solar cell combining a lead-free perovskite top cell based on methylammonium tin iodide (MASnI3) with a silicon bottom cell. Molybdenum trioxide (MoO3) serves as the hole transport layer (HTL) in the perovskite cell, providing favorable energy alignment and chemical stability for efficient charge extraction. Careful passivation of interfacial defects at the MoO3/MASnI3 interface minimized non-radiative recombination and enhanced hole transport. The optimized perovskite sub-cell achieved a power conversion efficiency (PCE) of 20.48%, while the silicon bottom cell reached 15.72%, resulting in a tandem PCE of 34.19%. These results underscore the critical role of interfacial defect control and inorganic HTL engineering in improving lead-free perovskite/silicon tandem performance. This tandem architecture offers a promising route toward scalable, environmentally friendly photovoltaic devices surpassing single-junction efficiency limits.