Robust Adsorption of Self‐Assembled Monolayer on NiOx via Multiple Hydrogen Bonds for Stable Inverted Perovskite Solar Cells

Abstract

ABSTRACT In inverted perovskite solar cells, self‐assembled molecules (SAMs) employed as hole‐transport layers can significantly improve device performance, with power conversion efficiencies currently exceeding 27%. However, the non‐uniform and weak adsorption of SAMs on metal oxide substrates leads to severe non‐radiative recombination at the buried interface, which remains a critical bottleneck for long‐term operational and thermal stability. In this study, heptafluorobutyramide (HA) or heptafluorobutylimidamide (HM) is introduced into MeO‑4PACz to tailor its adsorption on the NiO x surface. Leveraging multiple hydrogen‑bonding interactions between HM and MeO‑4PACz, the resulting SAMs adopt an inclined orientation of approximately 60° relative to the NiO x surface. This configuration increases the proportion of Ni 3 + on the substrate and raises the surface coverage from 0.912 to 1.236. It also effectively passivates undercoordinated Pb defects at the buried interface, enhances interfacial uniformity, and suppresses non‑radiative recombination. Using a vacuum‑flash processing method, HM‑optimized devices achieve a champion efficiency of 26.99% (certified steady‑state efficiency 26.62%) and reach 20.36% on a large‑area module with an active area of 809.69 cm 2 . Moreover, small‐area devices retained 92% and 87% of their initial efficiency after 1500 h of maximum power point tracking at 25°C and 60°C, respectively.