Cooperative Assembly Drives Buried Interface Engineering for Efficient Inverted Perovskite Solar Cells

Self-assembled monolayers (SAMs) containing carbazole and phosphonic acid groups have emerged as effective hole-transport layers (HTLs) for high-performance inverted perovskite solar cells (PSCs). However, the intrinsic aggregation tendency of SAM molecules often compromises interfacial uniformity, inducing non-radiative recombination and limiting device efficiency and stability. Here, we report a synergistically assembled chemically heterogeneous (SACH) interfacial layer constructed by integrating [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz) with carbazole-9-ethanol (CE). In this strategy, CE promotes favorable heteromolecular π-associated and dispersion interactions with Me-4PACz, thereby moderating excessive Me-4PACz self-association, improving interfacial uniformity, and enhancing charge extraction. Meanwhile, the hydroxyl group of CE supports an O─H···I^- interaction with perovskite, contributing to interfacial defect passivation and suppressed buried-interface recombination. As a result, devices employing the SACH layer achieve a PCE of 27.06% (certified 26.86%). Under maximum power point tracking in ambient air at 65°C, encapsulated SACH-based devices retained 88.6% of their initial efficiency after 500 h. Large-area perovskite modules (30 × 30 cm²) further demonstrate promising performance with an efficiency of 21.90%, highlighting the broad applicability of this cooperative interfacial design for scalable perovskite photovoltaics.