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 °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 °C) processed Pvsk-Br film via the SAG method, which presents the highest reported efficiency for inorganic CsPbIBr₂ solar cells thus far.