Hysteresis-free, stable and efficient perovskite solar cells achieved by vacuum-treated thermal annealing of CH3NH3PbI3

摘要

The lead halide-based perovskite solar cells have emerged as a promising candidate in photovoltaic applications. However, the precise control over the morphologiy of the perovskite films (minimizing pore formation) and enhanced stability and reproducibility of the devices remain challenging, even though both will be necessary for further advancements. Here we introduce vacuum-assisted thermal annealing as a means of controlling the composition and morphology of the CH_3NH_3PbI_3 films formed from PbCl_2 and CH_3NH_3I as precursors. We identify the critical role that the CH_3NH_3Cl generated as a byproduct during the pervoskite synthesis plays for the photovoltaic performance of the perovskite film. Removing this byproduct through vacuum-assisted thermal annealing we succeeded in producing pure, pore-free planar CH_3NH_3PbI_3 films showing high conversion efficiency (PCE) reaching 14.5%). Removal of CH_3NH_3Cl strongly attenuate the photocurrent hysteresis.