In this study, nitrogen doped CQDs (N-CQDs), as a novel additive, were successfully synthesized and characterized by XPS, TEM and UV–Vis spectrometry techniques. Importantly, we introduced N-CQDs in CH3NH3PbI3 solar cells. The results indicated that nonradiative charge back recombination decreased and the trap states in the absorber layer were passivated when N-CQDs was used an additive in CH3NH3PbI3 solution. Additionally, the morphological characterization results indicated that the crystallization problems and defects on perovskite surfaces can be easily resolved by N-CQDs additive in perovskite solution. A significant improvement in power conversion efficiency at a yield of 14% is achieved by doping of 3 vol% of N-CQDs, thanks to enhancement of charge transport properties due to the morphological and electrical changes. Herein, we propose an effective and novel additive for the fabrication of high efficiency perovskite solar cell, which can be seen that this method is simple.