Rational Solvent Annealing for Perovskite Film Formation in Air Condition (July 2017)

The past few years have witnessed a rapid growth in research and development activities for the emerging hybrid perovskite solar cells (PSCs), whose power conversion efficiencies have approached that of the commercialized silicon solar cells. In this regard, we try to develop a rational and accurately controllable solvent annealing method in air condition to maintain cost effective solar energy for PSCs. We have tailored the perovskite crystal growth process by optimizing dimethyl sulfoxide (DMSO) vapor annealing parameters, including the vapor concentration, the annealing time duration, and time point. The result shows that film-through large grains and sharply reduced surface defects can be obtained for perovskite film when the DMSO vapor annealing treatment is set at the initial stage of crystal growth, followed with mere thermal annealing for at least 20 min to reconstruct the perovskite crystal. Our results have supplied strong evidences for the scenario of perovskite film surface dissolution in DMSO vapor and the key role of atmosphere at the initial stage of crystal growth process for the final perovskite film morphology.