Advances in SnO for Efficient and Stable n-i-p Perovskite Solar Cells.

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 as an effective electron transport layer in these devices. In this article, the key advances in SnO development are reviewed, including various deposition approaches and surface treatment strategies, to enhance the bulk and interface properties of SnO for highly efficient and stable n-i-p PSCs. In addition, the general materials chemistry associated with SnO along with the corresponding materials challenges and improvement strategies are discussed, focusing on defects, intrinsic properties, and impact on device characteristics. Finally, some SnO 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.