Stability of mixed-halide wide bandgap perovskite solar cells: Strategies and progress

Benefiting from the superior optoelectronic properties and low-cost manufacturing techniques, mixed-halide wide bandgap (WBG) perovskite solar cells (PSCs) are currently considered as ideal top cells for fabricating multi-junction or tandem solar cells, which are designed to beyond the Shockley-Queisser (S-Q) limit of single-junction solar cells. However, the poor long-term operational stability of WBG PSCs limits their further employment and hinders the marketization of multi-junction or tandem solar cells. In this review, recent progresses on improving environmental stability of mixed-halide WBG PSCs through different strategies, including compositional engineering, additive engineering, interface engineering, and other strategies, are summarized. Then, the outlook and potential direction are discussed and explored to promote the further development of WBG PSCs and their applications in multi-junction or tandem solar cells.