Abstract
All-inorganic halide perovskites hold promise for emerging thin-film photovoltaics due to their excellent thermal stability. Unfortunately, it has been challenging to achieve high-quality films over large areas using scalable methods under realistic ambient conditions. Herein, we investigated the coupling between the fluid dynamics and the structural evolution during controlled film formation for ambient scalable fabrication of CsPbI2Br perovskite films using blade coating. We simultaneously overcame the negative influences of moisture attack and the Bénard-Marangoni instability in the drying ink and achieved an ideal sequential crystallization with changing halide composition during the film formation. As a result, we produced highly crystalline, uniform, and pinhole-free CsPbI2Br films with superior photophysical and transport properties. High-performance solar cells are fabricated to achieve power conversion efficiencies (PCEs) of 14.7% for small-aperture-area (0.03 cm2) devices and 12.5% for the large-aperture-area (1.0 cm2) ones, the highest PCE reported to date for large-area all-inorganic perovskite solar cells.
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•Fluid dynamics and phase transition act as a key for scalable coated CsPbI2Br film•Controlling drying dynamics can overcome the fluid instability and moisture attack•The ideal sequential crystallization with changing halide composition was observed•High photovoltaic performance was obtained for blade-coated CsPbI2Br PSCs
All-inorganic halide perovskites hold promise for improving the thermal stability of perovskite solar cells (PSCs), but their moisture sensitivity significantly limits scalable fabrication of high-quality thin films over large areas under ambient conditions. Upscaling of uniform and pinhole-free coatings is further complicated by the fluid dynamics of the ink and its solidification mechanisms. For the first time, we demonstrate the control of film formation during ambient-air scalable fabrication of CsPbI2Br perovskite films using blade coating and investigate the coupling between the fluid dynamics and the structural evolution during film formation. As a result, we achieve power conversion efficiencies of 14.7% (aperture, 0.03 cm2) and 12.5% (aperture, 1.0 cm2), which is the highest performance for 1.0 cm2 all-inorganic PSCs. These results present important lessons on controlling the solidification of inks for the practical fabrication of perovskite photovoltaics.
All-inorganic halide perovskites hold promise for emerging thin-film photovoltaics due to their excellent thermal stability. Unfortunately, it has been challenging to achieve high-quality thin films over large areas using scalable methods under realistic ambient conditions. Here, we provide important lessons on controlling the solidification and crystallization of CsPbI2Br perovskite inks during ambient scalable fabrication, with results of superior thin-film quality and device performance compared to lab-scale processes.