Numerous　trap　states　and　low　conductivity　of　compact　TiO2　layers　are　major　obstacles　for　achieving　high　power　conversion　efficiency　and　high-stability　perovskite　solar　cells.　Here　we　report　an　effective　Na2S-doped　TiO2　layer,　which　can　improve　the　conductivity　of　TiO2　layers,　the　contact　of　the　TiO2/perovskite　interface,　and　the　crystallinity　of　perovskite　layers.　Comprehensive　investigations　demonstrate　that　Na　cations　increase　the　conductivity　of　TiO2　layers　while　S　anions　change　the　wettability　of　TiO2　layers,　thus　improving　the　crystallinity　of　perovskite　layers　and　passivate　defects　at　the　TiO2/PVK　interface.　The　synergetic　effects　of　dopants　lead　to　a　champion　efficiency　as　high　as　21.25%　in　unencapsulated　perovskite　solar　cells　(PSCs),　with　much-improved　stability.　Our　work　provides　new　insights　on　anion　dopants　in　TiO2　layers,　which　is　usually　neglected　in　previous　reports,　and　also　proposes　a　simple　approach　to　produce　low-cost　and　high-performance　electron　transport　layers　for　high-performance　PSCs.