Theoretical advances in CH3NH3SnI3-based perovskite solar cells: A comprehensive review

Methylammonium tin iodide (MASnI3) has emerged as one of the most promising lead-free perovskite absorbers for next-generation photovoltaic devices owing to its suitable direct band gap, high absorption coefficient, excellent charge-carrier mobility, and environmentally benign composition. Over the past decade, extensive theoretical investigations have been conducted to understand and optimize the performance of MASnI3 based perovskite solar cells (PSCs) using computational approaches such as density functional theory (DFT), SCAPS-1D, SILVACO-TCAD, COMSOL, SETFOS, MATLAB-based simulations, and machine learning techniques. This review provides a comprehensive overview of these theoretical advancements, focusing on the intrinsic properties of MASnI3, simulation methodologies, device optimization strategies, and the evolution of predicted power conversion efficiencies (PCEs). Analysis of the reported studies reveals that improvements in absorber thickness, defect density, interface quality, energy-level alignment, and charge-transport layer selection are the primary factors driving enhanced device performance, with several optimized device architectures theoretically achieving PCEs exceeding 30%. However, the review also identifies important limitations in current modeling frameworks, including simplified defect assumptions, inadequate representation of Sn²⁺ oxidation and self-doping effects, limited consideration of degradation pathways, and insufficient validation against experimental observations. Based on these findings, future research should prioritize the development of realistic multiscale models that incorporate defect evolution, stability-related phenomena, and stronger simulation–experiment correlations. By synthesizing the current theoretical landscape, this review highlights both the opportunities and challenges associated with MASnI3 and provides guidance for the design of efficient, stable, and environmentally sustainable lead-free PSCs.