Solution‐State Supramolecular Engineering of Self‐Assembled Monolayers for High‐Performance Perovskite/Silicon Tandem Solar Cells

Carbazole‐based self‐assembled monolayers (SAMs), exemplified by [4‐(3,6‐dimethyl‐9H‐carbazol‐9‐yl)butyl]phosphonic acid (Me‐4PACz), are widely used as hole‐selective contacts in efficient perovskite/silicon tandem solar cells (TSCs). However, aggregation‐driven intermolecular organization in solution adversely affects the homogenization of SAMs on the substrate, compromising the performance of tandem devices. Herein, a supramolecular co‐assembly strategy is developed to modulate solution‐state intermolecular organization and suppress aggregation by introducing 4‐fluorophenylglycine hydrochloride, which co‐assembles with Me‐4PACz via dual‐site non‐covalent interactions. This strategy links solution‐state modulation to the formation of uniform SAM films, simultaneously realizing optimized energy alignment and reducing residual stress at the buried interface. Champion power conversion efficiencies (PCEs) of 23.66% and 33.91% (certified 33.5%) are achieved for 1.67 eV wide‐bandgap perovskite solar cells and 1 cm 2 two‐terminal monolithic perovskite/silicon TSCs, respectively. Moreover, the optimized tandem devices exhibit excellent operational stability under the ISOS‐L‐2 protocol, retaining 91% of the initial PCE after 1000 h of maximum power point tracking under one‐sun continuous illumination.