Exploring the Characteristics Addition Method for Estimating Bifacial Efficiency in Cs₃Sb₂I₉-Based Indoor Perovskite Solar Cells

The rapid growth of Internet of Things (IoT) devices has increased the demand for efficient indoor photovoltaics (IPV). Lead-free perovskite-inspired materials (PIMs), such as Cs₃Sb₂I₉, offer a promising alternative to conventional leadhalide perovskites due to their favourable electronic properties and non-toxic nature. Despite their potential, the bifacial performance of Cs₃Sb₂I₉ for indoor light harvesting remains largely unexplored. This study investigates Cs₃Sb₂I₉ as an absorber material in a bifacial solar cell with the optimized architecture AZO/TNT/Cs₃Sb₂I₉/SrCu₂O₂/Ni, designed for a bandgap of 1.95 eV. The monofacial reference device achieves a power conversion efficiency (PCE) of 3.7% under a 1000 lux WLED spectrum. Unlike previous studies that primarily report bifaciality factors, this work focuses on bifacial efficiency estimation. Results indicate that using ‘steel’ as the rear surface yields the highest PCE of 67.24%, demonstrating the potential of Cs₃Sb₂I₉-based bifacial solar cells for high-performance IPV applications.