Tin　oxide　(SnO2)　has　recently　emerged　as　a　promising　electron　transport　layer　(ETL)　for　all-inorganic　perovskite　solar　cells　(PVSCs)　owing　to　its　excellent　optical　and　electrical　properties.　However,　the　defects　of　the　perovskite　film　and　the　mismatch　of　the　energy　levels　between　the　SnO2　ETL　and　the　perovskite　film　result　in　an　increased　energy　loss　(Eloss)　which　therefore　leads　to　PVSCs　with　reduced　open-circuit　voltages　(VOCs)　and　efficiencies.　Herein,　we　demonstrate　the　use　of　KF-doped　SnO2　as　an　ETL　for　high　efficiency　all-inorganic　CsPbI2Br　PVSCs.　Through　KF　doping,　the　conduction　band　of　the　SnO2　film　can　be　regulated　to　better　match　that　of　the　perovskite　film　thereby　enhancing　the　electron　mobility　and　the　VOC　of　the　corresponding　PVSCs.　In　addition,　fluorine　ions　from　the　ETL　can　migrate　to　the　bottom　of　the　perovskite　layer　and　passivate　the　interface　between　the　ETL　and　the　perovskite　layer.　As　a　result,　the　VOC　of　PVSCs　increases　from　1.18　V　to　1.31　V　and　the　power　conversion　efficiency　(PCE)　of　the　resulting　PVSCs　increases　from　13.40%　to　15.39%.　This　facile　defect　passivation　strategy　on　the　ETL　should　be　valuable　for　fabricating　PVSCs　with　enhanced　performance.　This　journal　is　©　The　Royal　Society　of　Chemistry.