Abstract <p>Halide perovskites have established themselves as a transformative class of semiconducting materials in the photovoltaic landscape, distinguished by their exceptional, synergistic combination of electronic, optical and electrical properties. Herein, lead-free methylammonium tin triiodide (MASnI₃) is adopted as the absorber layer to eliminate the environmental hazards associated with lead-based perovskite compositions. This paper reports the simulation-based exploration of a potential of the electron transport layer (ETL) of zinc stannate (Zn₂SnO₄) coupled with diverse types of inorganic hole transport material (CuI, Cu₂O, NiO, and CuSCN) in a lead-free MASnI₃-based perovskite solar cell. This is the first reported configuration in which Zn₂SnO₄ serves as the ETL with inorganic hole transport layers (HTLs), rather than the existing configurations. Using the SCAPS-1D simulation software, the FTO/Zn₂SnO₄/MASnI₃/HTL/Au device architecture was analyzed to identify the most suitable hole-transport layer and to optimize the device’s key parameters. Cu₂O was the best-performing HTL among the tested HTLs, with an initial efficiency of solar cell device of 25.29%. The device performance was enhanced by systematically optimizing the HTL doping density, absorber thickness, acceptor doping concentration, and absorber defect density. To optimize the absorber’s realistic behavior, the defect density was identified. In fully optimized conditions, the solar cell device delivered an open-circuit voltage of 0.97 V, a short-circuit current density of 33.69 mA/cm², a fill factor of 81.90% and a peak power conversion efficiency of 26.77% at 300 K. The results define Zn₂SnO₄-based ETL in lead-free perovskite solar cells as an extremely efficient and sustainable photovoltaic technology, providing a useful benchmark for future experimental realization.</p>