In light of the urgent need for sustainable energy solutions, this research addresses the critical environmental
concerns of traditional lead-based perovskite materials. This paper explores advancements in an eco-friendly
tandem solar cell (TSC) that incorporates both lead-free wide bandgap perovskite and narrow bandgap antimony
selenide (Sb2Se3), focusing on optimization strategies utilizing TCAD numerical simulations. The study
begins with the calibration of experimental standalone solar cells based on wide bandgap lead-free perovskite
(1.62 eV) with a p-i-n heterostructure and narrow bandgap Sb2Se3 (1.2 eV) with an n-i-p configuration. The
research then transitions to evaluating the lead-free perovskite/Sb2Se3 system in a four-terminal (4-T) tandem,
followed by optimization of the top cell to an n-i-p heterostructure for compatibility with a two-terminal (2-T)
structure. Key optimization areas include replacing the organic hole transport layer (HTL) with other inorganic
candidates, conduction band offsets (CBOs), and absorber thicknesses. Through these optimizations, the 2-T
tandem design achieves a significant improvement, with a simulated PCE reaching 30.96 %. Numerical simulations
using TCAD tools are employed to predict performance and guide experimental modifications. This
research integrates material science and advanced TCAD simulations to optimize TSC performance with a focus
on eco-friendly materials for environmental sustainability.