Advances in SnO 2 for Efficient and Stable n–i–p Perovskite Solar Cells

Abstract Perovskite solar cells (PSCs) based on the regular n–i–p device architecture have reached above 25% certified efficiency with continuously reported improvements in recent years. A key common factor for these recent breakthroughs is the development of SnO 2 as an effective electron transport layer in these devices. In this article, the key advances in SnO 2 development are reviewed, including various deposition approaches and surface treatment strategies, to enhance the bulk and interface properties of SnO 2 for highly efficient and stable n–i–p PSCs. In addition, the general materials chemistry associated with SnO 2 along with the corresponding materials challenges and improvement strategies are discussed, focusing on defects, intrinsic properties, and impact on device characteristics. Finally, some SnO 2 implementations related to scalable processes and flexible devices are highlighted, and perspectives on the future development of efficient and stable large‐scale perovskite solar modules are also provided.