Challenges and Advances in Low‐Temperature Synthesis of Lead‐Free BaZrS₃ Chalcogenide Perovskite for Optoelectronics

Abstract Organic–inorganic hybrid lead halide perovskites (LHPs) have attracted considerable interest in photovoltaics due to their excellent power conversion efficiency (PCE) of up to 25.5% in solar cells. However, concerns over intrinsic instability and lead toxicity have led researchers to explore lead‐free alternatives such as chalcogenide perovskites, particularly BaZrS₃. This material exhibits a potential PCE of ≈30% and enhanced stability against environmental factors compared to LHPs. Current research into BaZrS₃ indicates a promising outlook for its application in optoelectronic devices. Recent synthesis techniques have focused on low‐temperature solution processes to facilitate their integration into devices. Despite significant advancements in synthesis methods, challenges persist in producing consistently high‐quality BaZrS₃ in the form of bulk, thin film, and nanocrystals. This review examines various synthesis methods for BaZrS₃ in its various forms, emphasizing the distinctive challenges in producing high‐quality film suitable for efficient devices. These approaches are outlined and critically compared with one another and with those used for LHPs, highlighting the urgent need to optimize them by correlating with the associated defect densities. The discussion also serves as a guideline for other similar phases for advancing the development of more efficient and environmentally friendly materials in renewable energy technologies.