Harmonious Layer Design in Wide‐Bandgap p‐i‐n Perovskite Solar Cells Using Carbazole and Triazatruxene‐Based Molecules

Abstract Recent advancements in self‐assembled monolayer (SAM) molecules have enhanced device efficiency and stability in wide‐band gap perovskite solar cells (PSCs). Although numerous mixed SAM strategies enhance hole extraction, comprehending the morphology of surfaces with two or more different deposited SAMs remains challenging. Contact angle analysis is employed to understand the SAM ratio and correlate it with device efficiency. A harmonious layer for the perovskite bottom interface is designed by integrating tripodal 3PATAT‐C3 and monopodal Me‐4PACz, thereby improving wettability and hole extraction. This layer promotes π–π stacking, enhancing perovskite crystallization quality and reducing strain. Consequently, PSCs with a harmonious layer retain 91% of their initial performance after 2000 h, with an open‐circuit voltage of 1.22 V and a fill factor of 84.1%. The study presents a novel approach for optimizing SAMs to achieve effective hole transport and reduced nonradiative recombination while ensuring a high‐quality deposited interface.