Self‐Assembled Monolayer‐Mediated Crystallization Improvement and Energy Level Optimization in Inverted Perovskite Solar Cells

Abstract The improved crystallization and precise energy level alignment achieved through self‐assembled monolayers (SAMs) implementation constitute a critical technological advancement, facilitating inverted perovskite solar cells (PSCs) with simultaneously enhanced power conversion efficiency (PCE) and operational stability. Here, a benzocarbazole‐derived SAM, BCPPA, is designed and synthesized as a hole‐transporting layer (HTL) by fusing an additional benzene ring in one side of the carbazole core. In comparison to the commonly used carbazole‐derived SAM of MeO‐2PACz, BCPPA exhibits a larger molecular dipole moment, a deeper HOMO energy level, and a more hydrophobic character. These factors contribute to a favorable buried interface between the SAM and the perovskite, thereby leading to an optimal crystallization of perovskite films and an improved energy level alignment. Additionally, the BCPPA‐based interface significantly reduces trap state density and suppresses nonradiative recombination. As a result, the BCPPA‐based PSC achieves a champion PCE of 25.28% (certified at 25.01%), surpassing the MeO‐2PACz‐based device with a PCE of 24.44%. The unencapsulated BCPPA‐based devices maintain 72% and 84% of their initial PCEs after aging at 85 °C for 600 h and tracking at maximum power point (MPP) for 512 h, respectively. The asymmetric SAM molecule is promising for fabricating highly efficient and stable inverted PSCs.