Dynamic synergy of tin in the electron-transfer layer and absorber layer for advancing perovskite solar cells: a comprehensive review

The landscape of metal halide-perovskite solar cells (MH-PSCs) has witnessed significant progress in terms of efficiency over the past decade. Nevertheless, concerns over the toxicity of lead (Pb)-based perovskite structures have restrained their full market potential. In response, the exploration of Sn perovskites has emerged as a promising alternative, fueled by their narrow band gaps, superior carrier mobilities, low-temperature production, economic viability, and reduced hysteresis. These Sn perovskites exhibit competitive PCE while addressing the toxicity issues of Pb-based PSCs. This comprehensive review delves into the pivotal role of Sn in advancing PSCs, offering a consolidated understanding of its multifaceted applications. The report extensively examines the incorporation of Sn-based electron-transfer layers (ETLs) and absorber layers within PSCs, encompassing various dimensions, such as synthesis techniques, optoelectrical features, the future of Pb-free solar cells, integration into double PSCs, and the impact of doping strategies. Finally, this review proposes the future perspectives and investigations needed to make Sn-based PSCs a viable alternative to Pb-based MH-PSCs.