Enhanced Buried Selective Contacts via Dual‐Sided Passivation for Efficient and Stable Perovskite Solar Cells

Abstract Self‐assembled monolayers (SAMs) play a crucial role in high‐performance perovskite solar cells (PSCs). However, the incompatibility between the nonpolar head groups of SAMs and the polar perovskite precursor solutions leads to SAM assembly defects and wettability issues, consequently impacting device efficiency. Moreover, the uneven distribution of hydroxyl groups on the surface of conventional transparent conductive oxide substrates is detrimental to SAMs onto them. Here, a dual‐sided passivation strategy is reported based on a co‐adsorbed approach, in which (4‐(3,6‐dimethyl‐9H‐carbazole‐9‐yl)butyl)phosphonic acid (Me‐4PACz) is doped with phaclofen (PLF) self‐assembly on the NiO_x substrate. By compensating for the unanchored sites of Me‐4PACz, the phosphonic acid groups in PLF adsorb onto the NiO_x surface, enabling more uniform and ordered anchoring of SAMs as well as improved wettability for perovskite deposition. This leads to optimized surface morphology and enhanced interface contact. Additionally, the amino groups in PLF passivate the defects at the buried perovskite interface, suppressing non‐radiative recombination during charge transport. The champion PSC fabricated using this co‐adsorbed strategy achieves a high fill factor of 84.92%, a power conversion efficiency of 24.04%, and excellent long‐term stability under ISOS‐D‐1I and ISOS‐T‐1I protocols, maintaining over 85% of the initial efficiency after >1000 h under thermal cycling conditions.