Corannulene‐Derivative‐Interfaced Inverted Perovskite Solar Cells with a Fill Factor above 0.87

Abstract The power conversion efficiency (PCE) and long‐term stability of perovskite solar cells (PSCs) are largely governed by the morphological, chemical, and optoelectronic properties of the hole transport layers (HTLs). Nickel oxide (NiO x ) is currently regarded as the most efficient HTL for state‐of‐the‐art PSCs. However, the strong chemical reactivity between high‐valence Ni species and perovskite components causes interfacial defects, inefficient hole transport, and chemical instability, particularly in NiO x /perovskite planar heterojunctions. To mitigate these issues, two amino‐terminated corannulene derivatives are successfully synthesized for the first time and employed them to modify the NiO x /Cs 0.05 (FA 0.95 MA 0.05 ) 0.95 Pb(I 0.95 Br 0.05 ) 3 (FA: formamidine, MA: methylamine) interface in inverted PSCs. Compared with pristine NiO x HTLs, the corannulene ammonium compounds notably enhance hole transport dynamics and reduce interfacial energy loss, yielding a PCE exceeding 25.8% along with improved long‐term operational stability. Notably, the optimized device achieves a fill factor of 0.87, among the highest reported for PSCs with NiO x ‐based HTLs. Overall, this study highlights the effectiveness and substantial potential of corannulene‐based interfacial materials for achieving highly efficient and stable PSCs.