Preparation of efficient and stable FA0.75MA0.25SnI3 perovskite solar cells using passivation materials with multiple F hydrophobic group

Although Sn-based perovskite solar cells (PSC) have impressive conversion efficiency, their stability needs to be improved. Herein, 3,4,5-trifluorophenol (C₆H₃F₃O) containing –F and –OH groups was introduced to improve the film stability and quality of FA_0.75MA_0.25SnI₃. –F groups with low surface energy cause C₆H₃F₃O to spontaneously migrate to the air-solution interface and attract the SnI₆⁴⁻ octahedron to the solution-air surface through hydrogen bond interactions between –OH and I. This leads to preferential nucleation of dense, high-quality perovskite films at the solution-air surface and orderly growth from top to bottom. Additionally, C₆H₃F₃O is bonded to the surface of the film, and the outward-facing hydrophobic –F groups effectively shield FA_0.75MA_0.25SnI₃ from water infiltration. The C₆H₃F₃O-doped PSC exhibited a champion efficiency of 10.47 % and long-term stability of over 1000 h, retaining 80 % of its initial efficiency (in N₂).