Mixed Carbazole Self-Assembled Monolayers Enable Scalable Large-Area (>5 cm2) Efficient Wide Bandgap Perovskite Solar Cells

Scalability and operational stability remain critical challenges for wide-bandgap perovskite solar cells (PSCs). Here, we report a mixed self-assembled monolayer (SAM) based on a carbazole moiety as a hole transport layer (HTL) to enable large active area (>5 cm2) PSC fabrication. Buried-interface reveals a compact grain size, reduced pinholes, and enhanced large-area film homogeneity of perovskite films prepared on mixed SAM. Top photoluminescence (PL) study show a recombination exponent (k) of 1.175 for the mixed-SAM HTL/perovskite films, indicating suppressed non-radiative losses. Optimized small-area devices (1.2 cm2) achieve a power conversion efficiency (PCE) of 20.30%, with an open-circuit voltage (VOC) of 1.204 V and fill factor (FF) of 81.32%, alongside enhanced damp-heat stability (T75 > 680 h). Voltage and FF losses are analyzed via transient PL based analytical model and empirical FF model, respectively. Upon scaling to 5.2 cm2, a PCE of 18.88% was maintained with only ∼7% relative efficiency loss majorly associated with reduced FF due to increased series resistance with increased area by almost 433% of the transparent conducting oxide substrate. These results establish mixed-SAM engineering with optimal chemical and electronic properties as an effective route toward scalable, efficient, and stable wide-bandgap PSCs.