Controlled growth of organic–inorganic hybrid CH3NH3PbI3 perovskite thin films from phase-controlled crystalline powders

Abstract

High-quality CH₃NH₃PbI₃ (MAPbI₃) crystalline powders were synthesized from a dispersion of MAPbI₃ solution (solvent: N,N-dimethylformamide (DMF)) in the antisolvent dichloromethane. They were used as starting chemicals for precursor solutions. The PbI₂–DMF-, perovskite-, and PbI₂–MAI (methylammonium iodide)–DMF-dominant phases were preferentially formed under conditions of excess PbI₂, moderate, and high-excess MAI input ratios, respectively. The input ratio of powders in fabricating the thin MAPbI₃ films strongly affected not only the morphology and structure of the films, but also the photovoltaic performance of the devices using them. The devices were constructed as follows: Au/hole-transporting material/MAPbI₃/mesoporous TiO₂ layer/TiO₂ blocking layer/F-doped SnO₂. The best device performance was obtained from the powder with a specific ratio of PbI₂ : MAI = 1 : 1.6; the device exhibited a power conversion efficiency of ∼16% at 1.5G standard conditions. Our proposed method could provide a simple and versatile solution-based approach for a low-cost perovskite solar cell fabrication technology.