Compact TiO2 is well-known electron transport material in sensitized solar cells and perovskite solar cell. However, because of the unsuitable energy level and slow electron extraction of TiO2, the planar TiO2 perovskite solar cell showed low power conversion efficiency with high hysteresis. Here, the planar TiO2 electron transport layer is modified with p-type CuI for perovskite solar cells. It is found that the polarity of the CuI-modified TiO2 surface pull electrons to the surface of the TiO2, which improves electron extraction and makes barrier-free energy level. Furthermore, the radiative recombination is also reduced by high extraction. The final device shows a 19.0% high efficiency with reduced hysteresis by removal of trap s<span style="font-size:10.8333px">tate</span>.