In recent years,flexible perovskite solar cells have received extensive attention and rapid development due to their advantages of lightweight,portability,wearability and applications in near-space.However,due to the limitations of their preparation process and other factors,high-efficiency and large-area flexi-ble perovskite solar cells still have a lot of room for development.In our work,a flexible perovskite solar cell(PEN/ITO/SnO2/KCl/Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3/spiro/Au)was prepared using a low tem-perature(no higher than 100℃)solution process,and the device with the highest efficiency of 16.16％ was obtained by adjusting the concentration of the KCl modified layer.Meanwhile,the efficiency of the large area(1 cm2)flexible solar cell was higher than 13％.At the same time,the passivation of the KCl interface modification layer inhibits the formation of the defect states,which reduced the surface recom-bination of the perovskite and improved the carrier transport performance,and the hysteresis effect of the device was also reduced accordingly.