Seed-Assisted Growth for Low-Temperature-Processed All-Inorganic CsPbIBr2 Solar Cells with Efficiency over 10%

All-inorganic CsPbIBr2 perovskite has recently received growing attention due to its balanced band gap and excellent environmental stability. However, the requirement of high-temperature processing limits its application in flexible devices. Herein, a low-temperature seed-assisted growth (SAG) method for high-quality CsPbIBr2 perovskite films through reducing the crystallization temperature by introducing methylammonium halides (MAX, X = I, Br, Cl) is demonstrated. The mechanism is attributed to MA cation based perovskite seeds, which act as nuclei lowering the formation energy of CsPbIBr2 during the annealing treatment. It is found that methylammonium bromide treated perovskite (Pvsk-Br) film fabricated at low temperature (150 degrees C) shows micrometer-sized grains and superior charge dynamic properties, delivering a device with an efficiency of 10.47%. Furthermore, an efficiency of 11.1% is achieved for a device based on high-temperature (250 degrees C) processed Pvsk-Br film via the SAG method, which presents the highest reported efficiency for inorganic CsPbIBr2 solar cells thus far.