Asymmetric Dimethyl‐Indenocarbazole Phosphonic Acid Molecules with Expanded π‐Conjugation for Inverted Perovskite Solar Cells

Abstract As successfully used in perovskite solar cells (PSCs), most carbazole core designs of self‐assembly monolayer molecules are still confined in symmetrical configurations, limiting the progress of their based p‐i‐n PSCs. Here, a π‐conjugation extended carbazole of 7,7‐dimethyl‐5,7‐dihydroindeno[2,1‐b]carbazole (DMICPA) is designed and synthesized to effectively modulate its dipole and energy level alignment, and herein enhancing the charge transport at the interface. Meanwhile, two methyl groups on the asymmetric indene structure can suppress the molecular aggregation to uniform the space distribution of DMICPA at the surface of ITO. As a result, the DMICPA based PSC achieves a power conversion efficiency (PCE) of 26.27% (certified at 25.74%), which can maintain 93% of the initial efficiency after 1000 h maximum‐power‐point tracking aging test following ISOS‐L‐2I protocol. Additionally, when DMICPA is utilized as p ‐dopants in PSCs without pre‐depositing hole transport layers (HTLs), the champion device also obtains a PCE of 25.40%. Both application scenarios in PSCs overwhelm the counterparts of 4PACz. This work paves a new way to design SAM molecules for efficient PSCs.