Control of the Nucleation and Growth of the Lead Acetate Solution Derived CH₃NH₃PbI₃ Films Leads to Enhanced Power Conversion Efficiency

Control of the nucleation and growth of the CH₃NH₃PbI₃ (MAPbI₃) phase is one of the important issues in the development of the high-performance MAPbI₃ perovskite solar cells. In this work, we demonstrated a novel and easy nucleation-controlling process to fabricate high-performance MAPbI₃ solar cells using lead acetate as a precursor. The morphology and crystallinity of the final annealed perovskite film is greatly influenced by the intermediate phase in the precursor film. Efficient removal of the solvent and reactants by the use of long-time spin coating process makes the MAPbI₃ nucleate at room temperature and grain coarsening during the anneal, resulting in the annealed films with smooth surface and high compactness. Precise control of the spin coating time made the average power conversion efficiency of the MAPbI₃ solar cells increase from 12-13% to 15-16%.