Organic-inorganic hybrid perovskite materials have recently attracted extensive attentions because of their intriguing optoelectronic properties for photovoltaics [1-3].The power conversion efficiency (PCE) of perovskite solar cells (PSCs) experienced an incredible rise from 3.8% to 25.5% within a decade, which can be attributed to new materials and thin-film technologies [4,5].Among varied thin-film technologies, vacuum-based thin-film technologies are qualified candidates.Until the year 2013, high-performance methylammonium lead iodide (MAPbI3) perovskite films were first formed by using a vapor-solid reaction method (VRM) [6].Then, formamidinium (FA)-based perovskite films with formulas of FAPb(BryI1-y)3 or CsxFA1-xPb(BryI1-y)3 were also formed through VRM [7-12].However, performances for VRM-processed perovskite films are not comparable with solutionprocessed perovskite films in a long time [13].The major reason is that both methylammonium iodide (MAI) and formamidinium iodide (FAI) vapor suffer from low reaction activity to PbI2 film.In a typical solution process, ions exchange in perovskite materials complete within seconds, however, up to 120-150 min are needed in a typical VRM [8,12].