A simplified multi-drop coating method that improves the grain size and film quality is introduced to construct and stabilize a pure a-phase formamidinium (FA) lead iodide ((NH2)(2)CHPbI3, FAPbI(3)) perovskite layer. The developed method is then extended to fabricate an FA and methylammonium (MA) (FA/MA) mixed cation perovskite film under ambient conditions. The acquired FAPbI3 film contains micronsized large grains with preferred [111] orientation, which dramatically reduced the grain boundary area and the associated charge recombination to provide high short-circuit current densities and power conversion efficiencies (PCE) of up to 23.86 mA cm(-2) and 17.66%, respectively. The open-circuit voltage of the device and the efficiency are further improved after extending this method to the FA/MA mixed perovskite film. Finally, the highest PCE reached 19.3%. (C) 2017 Elsevier B.V. All rights reserved.