Secondary lateral growth of MAPbI₃ grains for the fabrication of efficient perovskite solar cells

The morphology and optoelectronic properties of perovskite films are the key to high-performance perovskite solar cells (PSCs). Here, a facile non-destructive interface ethanol/chlorobenzene (EtOH/CB) post treatment was established for the lateral grain growth of MAPbI₃ perovskite films and fabrication of efficient solar cells. The alcoholic treatment leads to perovskite grain coarsening and a secondary growth in the average grain size from 38.88 μm to 89.59 μm. The enlargement of the perovskite crystals induced a notable defect passivation and attenuated charge recombination centers as confirmed by photoluminescence, electrochemical impedance spectroscopy, and photocharge extraction by a linearly-increasing voltage. Accordingly, inverted planar PSC devices showed an 18% enhancement in the overall power conversion efficiency using this alcoholic post-treatment under ambient fabrication conditions. Our results demonstrate a versatile strategy for the lateral growth of perovskite photovoltaics and beyond.