Halides‐Enhanced Buried Interfaces for Stable and Extremely Low‐Voltage‐Deficit Perovskite Solar Cells

defects and perovskite cations, leading to retarded perovskite crystallization and high-quality perovskite films with reduced residual stress. These improved properties enable champion efficiencies of 24.2% (the control: 20.5%) and 22.1% (the control: 18.7%) in rigid and flexible devices with extremely low voltage deficit down to 386 mV, all of which are among the highest reported values for PSCs with a similar device architecture. In addition, the resulting devices exhibit marked improvements in the device longevity under various stressors of humidity (>5000 h), light (1000 h), heat (180 h), and bending test (10 000 times). This method provides an effective way to improve the quality of buried interfaces toward high-performance PSCs.