Advances in Interfacial Engineering for Stable and Efficient Sn–Pb Perovskite Solar Cells

This review provides a comprehensive understanding of the critical role of interface engineering in enhancing the efficiency and stability of mixed Sn–Pb perovskite solar cells (PSCs). We primarily focus on the p–i–n architecture, systematically addressing the fundamental challenges and recent strategic breakthroughs at both the top exposed perovskite surface and the bottom buried interface. By detailing how surface engineering approaches mitigate interfacial defects and optimize charge‐carrier dynamics, this review emphasizes the direct correlation between precise interface control and the rapid performance enhancement in narrow‐bandgap single‐junction devices. Furthermore, we extend this discussion to the interconnecting layers in all‐perovskite tandem solar cells, where interfacial optimization is crucial for achieving effective charge transport. Ultimately, this review offers strategic perspectives on overcoming current interfacial hurdles to facilitate the transition of Sn–Pb PSC technology from laboratory‐scale research to large‐scale industrial applications.