Dual‐Site Defect Passivation and δ ‐Phase Engineering for High‐Efficiency and Stable Perovskite Solar Cells
Organic–inorganic perovskite solar cells are limited by surface defects and instability. Conventional ammonium‐salt passivation often forms insulating 2D phases that hinder charge transport. Here, we report ethylammonium trifluoroacetate (EATFA) as a bifunctional surface treatment for FAPbI 3 films. EA + and TF...