Small molecule-driven directional movement enabling pin-hole free perovskite film via fast solution engineering

Organolead trihalide perovskite materials have been widely used as light absorbers in efficient photovoltaic cells. Solution engineering is a fast and effective method to fabricate perovskite films. Here, we report a fast precipitation of a pin-hole free perovskite film by small molecule-driven directed diffusion engineering. Solvent molecules diffuse easily and quickly by colliding with small molecules, e.g. helium. Fully compact perovskite films and highly efficient perovskite solar cells are achieved, and the devices show remarkable stability of ca. 90% original efficiency after more than 1000 hours of testing. The small molecule driving directed diffusion offers a promising fast precipitation of a perovskite film and highly efficient, stable perovskite solar cells.