Spatial Conformation\nEngineering of Aromatic Ketones\nfor Highly Efficient and Stable Perovskite Solar Cells

Carbonyl-containing\nmaterials employed in state-of-the-art\nhybrid\nlead halide perovskite solar cells (PSCs) exhibit a strong structure-dependent\nelectron donor effect that predominates in defect passivation. However,\nthe impact of the molecular spatial conformation on the efficacy of\ncarbonyl-containing passivators remains ambiguous, hindering the advancement\nof molecular design for passivating materials. Herein, we show that\naltering the spatial torsion angle of aromatic ketones from twisted\nto planar configurations, as seen in benzophenone (BP, 27.2°),\nanthrone (AR, 15.3°), and 9-fluorenone (FO, 0°), leads to\na notable increment of the electron cloud density around the carbonyl\ngroup, thus improving the passivation ability for lead-based defects.\nConsequently, the PSC performance also relies on the torsion angle\nof the aromatic ketones, with the coplanar FO-based PSC achieving\na highest power conversion efficiency (PCE) of 25.13% and retaining\n92% of its initial efficiency after 1000 h of operation at the maximum\npower point under continuous 1-sun illumination (ISOS-L-1I). Moreover,\na perovskite mini-module (14.0 cm<sup>2</sup>) containing FO exhibits\na PCE of 20.19%. Our findings highlight the influence of molecular\nconformation on the passivation effect of the carbonyl group, offering\ndeeper insight into the design and development of aromatic ketones\nas passivators for highly efficient and stable PSCs.