Review of Lead-free halide Perovskites as light-absorbers for photovoltaic applications

Abstract Over the last decade, lead-halide perovskites containing organic and inorganic components have become attractive materials for photovoltaic and optoelectronic applications. Their owing light-absorption properties and charge-transport characteristics have enabled perovskite solar cells (PSCs) to achieve power conversion efficiencies comparable to those of established silicon-based photovoltaic technologies. Despite these advances, concerns regarding the toxicity of lead remain a major difficulty to the large-scale commercialization of PSCs. Although modifications to the crystal structure and material composition have helped increase perovskite stability, eliminating hazardous lead is an important step toward developing environmentally sustainable alternatives. In this context, lead-free halide perovskites (LFHPs) have attracted considerable research interest because of their potential optoelectronic performance and reduced environmental impact. Recent studies have investigated their suitability for a wide range of applications, including solar energy conversion, light-emitting diodes (LEDs), photodetectors, and other optoelectronic devices. Research in this field primarily focuses on identifying alternative elements that can replace lead while maintaining desirable structural, electronic, and optical properties. Tin-based halide perovskites have shown significant potential for solar applications among the candidates under investigation due to their advantageous electronic properties and encouraging power conversion efficiencies. However, there are a lot of difficulties because of their vulnerability to oxidation and the ensuing material instability. Consequently, researchers are exploring alternative metal elements, including germanium, copper, antimony, and bismuth, to develop more stable and environmentally compatible perovskite materials. These compounds exhibit diverse structural as well as optoelectronic properties, making them promising candidates for next-generation lead-free optoelectronic and photovoltaic systems. However, more research is needed to enhance their effectiveness, long-term stability, and useful device performance.