Development of lead-free perovskite solar cells: Opportunities, challenges, and future technologies

Despite notable advantages and power conversion efficiency achieved by perovskite solar cells (PSCs), they could not hit the market commercially as perovskite solar cells are bottlenecked by the toxicity issue caused by the metal lead. Lead has proven toxicity issues that can harm human beings and the ecological system to a significant extent. And so, researchers around the world have started diving deep into revolutionary sustainable photovoltaics called non-toxic lead-free PSCs for a sustainable and safe environment. This is achieved by the substitution of lead in PSCs with non-toxic or less toxic substitute metals. This review article revolves around the substitution of lead with metals such as tin (Sn), germanium (Ge), titanium (Ti), silver (Ag), bismuth (Bi) and copper (Cu) in PSCs with their properties, sustainability and challenges. This review also discusses the ways undertaken to overcome stability and efficiency-related challenges encountered in the commercialization of lead-free non-toxic PSCs such as alteration of fabrication methods and introduction of additives. Finally, the review discusses the recent advancements/technologies used in lead-free perovskite solar cells and also predicts the future perspective/technologies and futuristic applications that can be implemented in lead-free PSCs.