Lead-free tin-based Perovskite Solar Cells (PSCs) have emerged as promising alternatives to their lead-based counterparts, offering reduced toxicity while maintaining favorable optoelectronic properties. Among the various device components, the electron transport material (ETM) plays a decisive role in determining charge extraction efficiency and recombination dynamics. In this work, we present a systematic numerical investigation of MASnI3 based PSCs employing ZnO and TiO2 as ETMs, using the SCAPS-1D simulation platform. Three distinct hole transport materials Spiro-OMeTAD, PEDOT:PSS, and Cu2O are evaluated, yielding six device architectures for comprehensive comparison. We analyze in detail the effects of absorber thickness, doping concentration, and operating temperature on photovoltaic performance. Our optimized configurations achieve power conversion efficiencies up to 26% for the TiO2/MASnI3/Cu2O structure. Notably, the superior performance of TiO2 is attributed to its significantly lower interface defect density compared to ZnO, which more than compensates for its lower electron mobility. While TiO2 demonstrates superior interfacial charge extraction and reduced recombination losses, ZnO retains distinct advantages in low-temperature processing and cost-effectiveness. This study provides quantitative design guidelines for selecting optimal ETM/HTM combinations in efficient and environmentally benign tin-based PSCs.
