摘要： Perovskite solar cell has made a steadily research progress with superior photovoltaic power conversion efficiency (PCE) over 25%. The quality of perovskite film is a key factor affecting device efficiency. Lewis bases such as urea, DMSO and thiourea etc. have been applied in perovskite precursor solutions for one-step processing to effectively control film morphology. Herein, we report urea treatment in a two-step processing for obtaining high quality methylammonium lead triiodide perovskite (CH3NH3PbI3) film. This is accomplished by immersing the PbI2 film into the mixture solution of urea/methylammonium iodide (MAI). The optimized urea concentration in the MAI solution is 0.4 mg/mL, attributing to larger-sized and better crystalline perovskite grains than that without urea additive. The main function of the urea additive is the formation of the adduct MAI·PbI2·O=C(NH2)2, retarding the crystallization process of the perovskite film. The steady-state and time-resolved photoluminescence measurements revealed that perovskite CH3NH3PbI3 grown using the optimized concentration of urea prolonged carrier lifetime and reduced carrier recombination. Finally, the carbon-based perovskite solar cells fabricated from the optimal urea concentration of 0.4 mg/mL achieved the enhanced photovoltaic performance with the highest PCE of 13.10% and an average value of 11.34%, in comparison to devices without urea treatment exhibiting an average PCE of only 8.67%.