Large-grain CH3NH3PbI3 film by incorporation of urea in one-step solution process

Abstract

The Lewis acid–base adduct is a comprehensive approach to modify crystallinity and surface morphology of perovskite, nevertheless, the key role of adduct in nucleation and growth mechanism is ambiguous. In our study, it was revealed that the size of perovskite colloidal clusters considerably increase when urea adds to the solution and this phenomenon controls the nucleation. In addition, the intermediate structures formed by urea govern the final perovskite morphology through retarding the perovskite crystal growth. Thus, large-grain CH3NH3PbI3 (MAPbI3) film with almost full surface coverage achieves by the incorporation of urea especially when antisolvent technique is applied during the spin coating. Finally, extremely large grains, larger than 100 micrometers, form via simultaneous use of dimethyl sulfoxide (DMSO) and urea in perovskite solution.