In perovskite solar cells(PeSCs), TiO₂ is used as an electron transporting layer due to its high electron affinity and high electron mobility. However, the back reaction between the photoinjected electrons and hole transporting materials could cause a loss of the performance of the solar cells. In this study, TiO₂ surface was modified with conjugated base via a simple dip coating process, and the resulting films were applied to electron transfer layers of PeSC. The PeSC with surfacemodified TiO₂ layer showed a power conversion efficiency of 11.0% in comparison to that (9.18%) of the reference device without surface modification, due to an enhancement in both the short-circuit current and open-circuit voltage.