Recent progress in Pb-, Sn-, and Pb–Sn-based inorganic perovskite solar cells: toward enhanced stability and efficiency

Abstract

All-inorganic metal halide perovskites have attracted increasing attention as promising materials for inorganic perovskite solar cells, owing to their superior thermal and chemical stability and wider bandgap tunability compared to organic–inorganic hybrid perovskites. However, inorganic perovskite has the problem of phase instability, as these materials are prone to undesirable phase transitions induced by both intrinsic and extrinsic factors. Such instability significantly degrades the long-term stability and efficiency of inorganic perovskite solar cells. In this review, we provide a comprehensive overview of Pb-, Sn-, and Pb–Sn-based inorganic perovskite solar cells. We systematically address various intrinsic and extrinsic factors that induce phase transitions and degrade the stability of inorganic perovskite. In particular, we focus on polymorphic transitions and examine how α/β/γ to δ transformations determine the optoelectronic properties in CsPbX₃, CsSnX₃ and their Pb–Sn alloys. In addition, we introduce recent strategies to suppress or mitigate these factors in order to develop long-term stable and highly efficient inorganic perovskite solar cells and inorganic perovskite-based tandem solar cells.