Efficient and Stable Inverted Perovskite Solar Cells Via a Multi‐Arm Donor–Acceptor Dipole Molecular Bridge

Abstract

ABSTRACT The rapid advancement of self‐assembled monolayer (SAM) engineering has substantially improved the photovoltaic performance of p‐i‐n perovskite solar cells (PSCs). However, interfacial defects, inefficient charge transport, and residual lattice strain at the SAM/perovskite interface still limit device efficiency and operational stability. Herein, we propose a multi‐arm donor–acceptor (D–A) dipole molecular bridge strategy for buried‐interface regulation. Two D–A type dipole molecules, N4IA and T4IA, were designed and synthesized to clarify the role of molecular‐arm engineering. Compared with N4IA, T4IA features a multi‐arm D–A framework with a larger molecular dipole, abundant triphenylamine‐based hole‐transport units, and multiple C═N/methoxy coordination sites. These structural features enable T4IA to optimize energy‐level alignment, build efficient hole‐transport pathways, accelerate charge extraction, and suppress interfacial nonradiative recombination. Meanwhile, the C═N and methoxy groups strongly interact with undercoordinated Pb 2+ defects, reducing trap states, alleviating residual lattice strain, and improving interfacial stability. The optimized p‐i‐n PSCs based on T4IA interfacial regulation achieve a champion PCE of 26.79% with enhanced long‐term operational and thermal cycling stability. This work provides a feasible molecular interface strategy for developing efficient and stable perovskite photovoltaic devices.