Hybrid Self‐Assembled Molecular Interlayers for Efficient and Stable Inverted Perovskite Solar Cells

Abstract Self‐assembled molecules (SAMs) have been widely employed as hole transport layers (HTLs) in inverted perovskite solar cells (PSCs). However, the carbazole core of [4‐(3,6‐dimethyl‐9H‐carbazol‐9‐yl)butyl]phosphonic acid (Me‐4PACz) is insufficiently effective for passivating defects at the “bottom” of perovskite films, and the weak anchoring ability of phosphate groups toward the NiO x substrate appears to promote the formation of dimers, trimers, and higher‐order oligomers, resulting in molecular accumulation. Herein, a novel technique is proposed to combine Me‐4PACz with different thiol molecules to modify the buried interface of PSCs. Molecular dynamics simulations and infrared scattering‐type scanning near‐field optical microscopy (IR s‐SNOM) results show that co‐depositing Me‐4PACz with thiol molecules forms hybrid SAMs that densely and uniformly cover the NiO x surface. The island‐like structure of the hybrid SAMs serves as a template for forming the perovskite bulk heterojunction composed of interpenetrating networks of MA‐rich and FA‐rich domains, enabling efficient charge generation and suppressed bimolecular recombination. Particularly, (3‐mercaptopropyl) trimethoxysilane (MPTMS) effectively prevents Me‐4PACz aggregation by forming a multi‐dentate anchor on the NiO x surface through hydrolytic condensation of ─OCH 3 groups, while its ─SH groups passivate uncoordinated Pb 2+ at the perovskite/HTL interface. Consequently, the resulting hybrid SAMs‐modified PSC achieve a champion photoelectric conversion efficiency (PCE) of 25.4% and demonstrated better operational stability.