Adhesively Bridging Co‐Self‐Assembled Monolayer and Perovskite Via In Situ Polymerization for Enhanced Stability of Inverted Perovskite Solar Cells

Abstract

The strategic utilization of self-assembled monolayers (SAMs) significantly advances the interfacial contact and power conversion efficiency (PCE) of inverted perovskite solar cells (IPSCs). However, inadequate adhesion between the SAM and perovskite layer remains a critical challenge, limiting further performance enhancement. Herein, a synergistic interface engineering strategy is introduced that combines a co-assembly approach with in situ polymerization to optimize the buried interface of perovskite film. Specifically, 11-Mercaptoundecylphosphoric acid (MPA) is incorporated into a SAM to form co-SAMs, improving homogeneity and mitigating defects at the NiO_x surface. Simultaneously, the ionic liquid (IL) monomer 1-Allyl-3-vinylimidazolium bis((trifluoromethyl)sulfonyl) imide (AVMTF₂) is incorporated into the perovskite precursor. The aggregation of ILs cation at the bottom interface facilitates in situ polymerization via sulfhydryl end groups, forming the POL-AVM polymer at the perovskite/SAM interface. This polymer enhances interfacial adhesion, regulates perovskite crystallization, and reinforces structural integrity by strongly anchoring organic cations through multiple hydrogen bonds. As a result, this synergistic strategy achieves a champion PCE of 26.25% (certified 26.04%), along with excellent long-term stability, retaining 95.6% of its initial efficiency after 1000 h of continuous operation under the ISOS-L-2I protocol.