Influence of moisture on the preparation, crystal structure, and photophysical properties of organohalide perovskites

The effect of preparing lead-based organohalide perovskites under inert conditions has been investigated. We find that when prepared under anhydrous conditions, only poorly crystalline powders were obtained. On exposure to small amounts of moisture a rapid crystallization into the expected cubic unit cell for CH3NH3PbBr3 and tetragonal cell for CH3NH3PbI3 is observed. While the as-prepared iodide phase is non-emissive, the lifetime of the emission for the bromide is found to be much longer when prepared under atmospheric conditions.