Substitutional Growth of Methylammonium Lead Iodide Perovskites in Alcohols

Methylammonium lead iodide (MAPbI3) perovskites are organic–inorganic semiconductors with long carrier diffusion lengths serving as the light‐harvesting component in optoelectronics. Through a substitutional growth of MAPbI3 catalyzed by polar protic alcohols, evidence is shown for their substrate‐ and annealing‐free production and use of toxic solvents and high temperature is prevented. The resulting variable‐sized crystals (≈100 nm–10 µm) are found to be tetragonally single‐phased in alcohols and precipitated as powders that are metallic‐lead‐free. A comparatively low MAPbI3 yield in toluene supports the role of alcohol polarity and the type of solvent (protic vs aprotic). The theoretical calculations suggest that overall Gibbs free energy in alcohols is lowered due to their catalytic impact. Based on this alcohol‐catalyzed approach, MAPbI3 is obtained, which is chemically stable in air up to ≈1.5 months and thermally stable (≤300 °C). This method is amendable to large‐scale manufacturing and ultimately can lead to energy‐efficient, low‐cost, and stable devices.