Advancements in AgBiS2 thin film solar cells: strategies, challenges, and perspectives

Recently, ternary chalcogenide AgBiS2 (ABS) gained enormous attention as it is considered an eco-friendly, non-toxic, and cost-effective alternative as a photo-absorber for photovoltaics (PVs) owing to its excellent optoelectronic properties, i.e. a high absorption coefficient (>105 cm−1), tunable bandgap, and environmental stability. Unlike CuInGa(S,Se)2 (CIGSSe), perovskites, and other materials, the ultrathin layer of AgBiS2 is about 35 nm, enough to absorb a significant portion of the solar spectrum, making it advantageous for PVs. However, the power conversion efficiency of AgBiS2 thin film solar cells (TFSCs) has been reported to be around ∼11% lower than that of CIGSSe (23.35%). This review highlights the latest strategies for further advancement in the performance of AgBiS2 TFSCs, mainly focusing on the intrinsic properties of AgBiS2, absorber synthesis methods, device fabrication techniques, challenges, and prospects. Herein, innovative strategies such as device design, bandgap engineering, doping, surface/interface passivation, and integrating mesoporous layers are reviewed. Furthermore, the review outlines a roadmap for developing high-efficiency and commercially viable AgBiS2-based PVs for a next-generation sustainable future.