摘要： Formamidinium (FA) based perovskite solar cells (PSC) shows enhanced stability comparing to their methylammonium (MA) based counterpart. However, its stability needs to be further enhanced for the potential commercial applications. We demonstrate here that the high-quality thin film can be obtained for FA-based perovskite with remarkably enhanced moisture stability using a confined-pressure annealing (CPA) processing and controlling the amount of Cs introduced into the FAPbI3 perovskite precursor solution. Without additional 2D cation additives, surface passivation or encapsulation, no phase degradation was observed for the Cs0.1FA0.9PbI3 perovskite under a humidity of 70 RH% over 500 hours. The unencapsulated device maintained over 70% performances for 500 hours comparing to <80 h of the conventional processed devices, which is the comparable to the outstanding moisture stability of the 2D/3D perovskites. The FA-based perovskite grain size was promoted to over 1 micrometer with a high static water contact angle up to 112°. The surface cations composition was varied with the concentrated FA cation species at surface while homogenized Cs/FA distribution inside the film. The trapped state density and carrier recombination rate were also reduced with a high fill factor of 82% and the efficiency over 20.23%. This work suggests the intrinsic stability of the 3D perovskite could be further enhanced with adjusting of the surface compositions during the crystallization process.