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

High-quality CH 3 NH 3 PbI 3 (MAPbI 3 ) crystalline powders were synthesized from a dispersion of MAPbI 3 solution (solvent: N , N -dimethylformamide (DMF)) in the antisolvent dichloromethane. They were used as starting chemicals for precursor solutions. The PbI 2 -DMF-, perovskite-, and PbI 2 -MAI (methylammonium iodide)-DMF-dominant phases were preferentially formed under conditions of excess PbI 2 , moderate, and high-excess MAI input ratios, respectively. The input ratio of powders in fabricating the thin MAPbI 3 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/MAPbI 3 /mesoporous TiO 2 layer/TiO 2 blocking layer/F-doped SnO 2 . The best device performance was obtained from the powder with a specific ratio of PbI 2 : 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. High-performance MAPbI 3 perovskite solar cells with 16% efficiency are fabricated from phase-controlled crystalline powders.