Cation–Anion Synergy Enables Uniform and Stable SAMs for High‐Efficiency Perovskite/TOPCon Tandem Solar Cells

ABSTRACT Hole‐selective self‐assembled monolayers (SAMs) have recently boosted the efficiency of perovskite/silicon tandem solar cells (TSCs), but constructing dense, uniform, and particularly stable SAMs on textured surfaces remains challenging. Here, a cation–anion synergistic strategy is employed to suppress SAMs clustering and enhance molecular anchoring stability. The combined effects of cation–π interaction and phosphonic acid deprotonation enable the formation of high‐quality SAMs and perovskite absorbers, while simultaneously improving their interfacial contact at the buried interface. The resulting wide‐bandgap perovskite solar cells yielded a power conversion efficiency (PCE) of 23.04%, maintaining 84% of their initial efficiency after 1500 h of maximum power point (MPP) tracking under ISOS‐L‐1 protocol. Moreover, a 1 cm ² monolithic perovskite/silicon tandem solar cell based on textured tunnel oxide passivated contacts (TOPCon) delivered an impressive efficiency of 32.13%, representing the highest reported value to date for perovskite/TOPCon tandems.