Hybrid　organic-inorganic　perovskites　have　attracted　tremendous　attention　for　solar　cell　application　due　to　their　outstanding　properties.　However,　further　studies　are　still　needed　to　fully　address　the　carrier　recombination　issue　at　grain　boundaries　which　lowers　the　device　performance,　and　its　environmental　stability　issues.　Fluoride　additive　engineering　is　found　to　be　a　good　method　to　successfully　passivate　defects　in　perovskite　films.　Here,　we　developed　a　simple　method　to　improve　the　device　power　conversion　efficiency　as　well　as　its　environmental　stability,　by　introducing　the　polytetrafluoroethylene　(PTFE)　additive　within　the　perovskite　organic　precursor　in　a　two-step　deposition　method.　The　built-in　electric　field　effect　induced　by　PTFE　induces　the　migration　of　photo-generated　carriers,　suppressing　the　electron-hole　recombination,　thus　improving　the　short　circuit　current　and　then　the　photovoltaic　performance.　We　obtained　a　maximum　efficiency　of　20.48%　for　PTFE　5%-based　PSCs　compared　to　the　pristine　one　which　was　only　14.27%.　Furthermore,　it　is　also　demonstrated　that　the　PTFE-based　PSC　device　exhibits　strong　environmental　stability.　The　device　presented　only　5%　PCE　loss　over　42　days　of　storage　in　an　ambient　environment.