Hafnium oxide interface stabilization for efficient, photothermally stable perovskite solar cells

layer (p denotes positive fixed-charge polarity) anchored 3-fluorophenylethylammonium iodide (3F-PEAI) through Hf⋯F interactions that also acted as a diffusion barrier against halide- and silver-ion migration. Devices achieved a power conversion efficiency of 27.1% (26.6% certified) and retained more than 90% of their initial efficiency for ~5000 hours under 1-sun equivalent illumination at 85°C in ambient air.