Large-grained perovskite films via FA x MA 1−x Pb(I x Br 1−x ) 3 single crystal precursor for efficient solar cells

Organometal trihalide perovskite solar cells (PSCs) based on multiple-site alloyed perovskite currently attract a surge of research interests owing to their extreme high solar-to-electric power conversion efficiency (PCE). Additionally, perovskite single crystals, proven to possess lower defect density, are highly anticipated to realize the full potential of perovskite materials. Herein, we for the first time proposes a facile and operable cooling-induced crystallization method to fabricate dual-site alloyed FAxMA1−xPb(IxBr1−x)3 single microcrystals with tunable bandgaps, which will later be employed as encouraging precursors to form high quality perovskite films with extended grain sizes and less grain boundaries. The corresponding solar cells showcase advanced charge transport and retarded recombination, leading to satisfying photovoltaic performance and heartening device stability (a champion PCE of 18.3% and a satisfying maintenance of ~83% initial PCE after 2000 h aging without encapsulation), indicating a promising protocol of fabricating miscellaneous single microcrystal perovskite precursors for highly efficient PSCs.