Multi-functional buried interface passivation for high-performance perovskite solar cells via 4-chloro-2,2,2-trifluoroacetophenone modification

The buried SnO 2 /perovskite interface with abundant multi-species defects is a critical obstacle to further boosting the performance of perovskite solar cells. In this study,a 4-chloro-2,2,2-trifluoroacetophenone (4-CTA) bridging molecule is developed to realize simultaneous bilateral passivation of this interface, where the carbonyl group, trifluoromethyl and chlorine atoms synergistically eliminate trap states on both sides. After modification, the oxygen vacancy ratio of SnO 2 decreases from 44.94% to 35.58%, accompanied by enlarged perovskite grains and accelerated electron extraction. A champion PCE of 24.29% is obtained for the optimized device. Even without encapsulation, 87.3% of the initial efficiency is retained after 30 days of dark ambient storage (25 °C, 40–60% RH, without illumination or load), demonstrating improved storage stability over the control. A facile synergistic interfacial methodology is developed herein for highly efficient perovskite solar cells.