Minimizing Surface Defects by Chemical Passivation for High-Performance Perovskite/Silicon Tandem Solar Cells

As the pursuit for cost reduction of photovoltaic technologies goes on, the interest in high-efficiency Si-tandem solar cells has been strongly increasing, among which perovskite/silicon has demonstrated impressive results and prospects for further enhancements. However, the existence of deleterious defects at the surface of wide-bandgap perovskite films in the top solar cells dramatically impedes the potential industrial applications of perovskite/silicon tandem solar cells. In this review, begin by summarizing the various types of defects and the passivation mechanisms to provide guidance for the passivation protocols. Then, it highlights the reasons for device performance enhancement of the most widely used passivation strategy, chemical bonding passivation, which works by either assembling a thin molecular layer (molecular passivation) or inducing the formation of a low-dimensional perovskite (heterojunction passivation) at the 3D perovskite surface. Next, an overview of the passivating treatments for perovskite films deposited on crystalline silicon and their fabrication requirements is presented. Finally, the challenges and knowledge gaps for breaking bottlenecks in the commercialization of perovskite/silicon tandem solar cells are proposed.