Improving the Stability of Wide Bandgap Perovskites: Mechanisms, Strategies, and Applications in Tandem Solar Cells

Abstract Tandem solar cells (TSCs) based on wide bandgap (WBG) perovskites have gained significant attention for their higher power conversion efficiency (PCE) compared to single‐junction cells. The role of WBG perovskite solar cells (PSCs) as the sub‐cell in tandem cells consists of absorbing high‐energy photons and producing higher open‐circuit voltages ( V _OC ). However, WBG PSCs face serious phase separation issues, resulting in poor long‐term stability and substantial V _OC loss in TSCs. In response, researchers have developed a range of strategies to mitigate these challenges, showing promising progress, and a comprehensive review of these strategies is expected. In this review, we discuss the stability mechanism in organic–inorganic hybrids and all‐inorganic WBG perovskites. Additionally, we conduct an in‐depth investigation of various strategies to enhance stability, including component engineering, additive engineering, interface engineering, dimension control, solvent engineering, and encapsulation. Furthermore, the application of the WBG sub‐cell in various TSCs is summarized in detail. Finally, perspectives are provided to offer guidance for the development of efficient and stable WBG sub‐cell in the field of TSCs.