Crystallization-activated moisture barrier for high-tolerance manufacturing of perovskite solar cells

Moisture promotes perovskite crystallization during annealing but only within a narrow humidity range, hindering the stable mass production of perovskite solar cells, especially for formamidinium lead iodide. To overcome this, we integrated a "crystallization-activated moisture barrier" into the perovskite film, which can exist in a liquid state/crystallization phase during the initial annealing to allow moisture to enter and promote crystallization, then migrate upward, and form a dense hydrophobic layer on the film surface to protect the perovskite from high humidity-caused damage. Such a "moisture barrier" enables the manufacturing of perovskite films to be insensitive to a wide range of relative humidity from 20% to over 90%. The barrier also regulates bulk crystallization and passivates surface defects. The crystallization-activated moisture barrier effectively reduces the sensitivity of perovskite films to humidity during annealing, which paves the way for high-tolerance manufacturing of perovskite photovoltaic devices.