Undercoordinated　lead　cations　and　halide　anions　on　the　surface　of　perovskite　layer　can　form　surface　trap　states　and　cause　electronic　disorders　which　reduce　the　performance　of　perovskite　solar　cells.　Nitrogen-doped　carbon　dots　(NCDs)　that　have　rich　nitrogen-　and　oxygen-containing　functional　groups　can　effectively　interact　with　the　unsaturated　metal　sites　and　halide　anions　on　the　surface　and　boundaries　of　perovskite　grains.　Herein,　low-cost　NCDs　are　utilized　as　efficient　additives　to　passivate　the　surface　of　a　solution-processed　CH3NH3PbI3　perovskite　film,　which　remarkably　reduce　charge　carrier　recombination,　as　evidenced　by　the　results　of　time-resolved　photoluminescence　and　electrochemical　impedance　spectrum　measurements.　FTIR　spectra　indicate　the　formation　of　hydrogen　bonds　between　the　undercoordinated　iodine　ions　on　perovskite　grains　and　hydroxyl　as　well　as　nitrogenous　groups　of　NCDs.　In　addition,　NCDs　additives　also　help　increase　interfacial　charge　transfer　from　perovskite　to　electron-transporting　layer,　leading　to　an　improvement　in　power　conversion　efficiency　for　the　solar　cell　device　from　12.12 ± 0.28%　(standard　cell　fabricated　in　same　conditions)　to　15.93 ± 0.15%.　©　2018,　Springer　Science+Business　Media,　LLC,　part　of　Springer　Nature.