Band bending reversal and enhanced electron mobility at the film surface achieved through a selective polishing strategy in tin–lead perovskite solar cells

Pyrophosphoric acid (PP) in isopropanol selectively dissolve the Sn component but not the Pb component at tin–lead (Sn–Pb) perovskite surface, which enables a low-defect film and a highest efficiency of 23.85% for Sn–Pb perovskite solar cells.