Dual Modulation of the Buried Interface in Inverted Perovskite Solar Cells With Heteroatom‐Conjugated Asymmetric Self‐Assembled Molecules

ABSTRACT Self‐assembled molecules (SAMs) have shown considerable promise as hole‐selective layers (HSLs) in high‐efficiency NiOx‐based inverted perovskite solar cells (i‐PSCs). However, inhomogeneous HSL formation caused by SAM detachment and intractable buried defects within the perovskite layer exacerbate interfacial energy losses, which limits further improvement in device efficiency and operational stability. Here, we propose a heteroatom‐conjugated asymmetric SAM‐additive (HASA) strategy that employs two novel SAMs, designated O‐AS and S‐AS, to address the issues of buried interface synergistically. These asymmetric expanded molecules are deposited on the NiOx surface and introduced into the perovskite precursor to achieve uniform molecular coverage and enhance perovskite crystallinity simultaneously. The dual modulation of the buried interface effectively optimizes the HSL uniformity, improves hole extraction/transfer, mitigates buried defects, and enhances the NiOx stability. Due to minimized interfacial energy loss, iPSCs treated by S‐AS achieve a champion power conversion efficiency (PCE) of 26.49% (25.70% for steady‐state output) and retain 97.3% of their initial PCE over 1100 h of maximum power point tracking under ISOS‐L‐2 testing protocol. This study presents an effective molecular synergetic approach to address SAM and buried‐interface problems in iPSCs through molecular engineering.