Tailoring CBTSSe Solar Cells for Indoor Photovoltaic Applications

These Solution-processed Cu2BaSn(S,Se)4 (CBTSSe) thin films have emerged as promising candidates for next-generation photovoltaics due to their earth-abundant and non-toxic constituents, as well as tunable bandgaps suitable for both outdoor and indoor applications. While significant progress has been made in optimizing CBTSSe-based solar cells for outdoor use, their potential for indoor energy harvesting, particularly for powering IoT devices, remains largely unexplored. This work investigates the performance of a CBTSSe-based device, originally designed for outdoor applications, under indoor light conditions. A baseline simulation model, calibrated against a 6.17% efficient experimental device, was developed using SCAPS. This model incorporates realistic material parameters and interface defect considerations. The absorber layer bandgap was optimized for indoor illumination (1.9 eV) and the impact of absorber thickness and defect density was systematically investigated. Furthermore, the buffer layer was modified by exploring different conduction band offsets and ultimately replacing Zn:CdS with ZnSe to enhance electron transport. Our simulations demonstrate a significant improvement in device performance under indoor WLED illumination (1000K lux), achieving a power conversion efficiency exceeding 30%. This study highlights the potential of CBTSSe as a viable material for high-performance indoor photovoltaics and contributes to the development of self-powered IoT devices