The light weight, good bending resistance and low production cost make flexible perovskite solar cells (PSCs) good candidates in wearable electronics, portable charger, remote power, and flying objects. High power conversion efficiency (PCE) plays a crucial role on obtaining the high mass specific power of flex-ible devices. However, the performance for flexible PSCs is still having a large room to be improved. Here, we added the 2-amino-5-cyanopyridine (ACP) molecule with a polar electron density distribution in the perovskite precursor solution to improve the performance of flexible PSCs. The cyano groups with electron-withdrawing ability are expected to passivate positively charged point defects, while amines with electron donating ability are expected to passivate negatively charged point defects in perovskite films. Thanks to the effective passivation of defects at the grain boundary and surface of perovskite films, the PCE of flexible PSCs is obviously increased from 16.9% to 18.0%. These results provide a universal approach to improve performance of flexible PSCs by healing the defects in perovskite films through electrostatic interactions.