We report on the effects of surface-modified TiO2 on the performance of dye-sensitized solar cells (DSSCs). TiO2 surface was modified with Na2CO3 via a simple dip coating process and the modified TiO2 was applied to photoelectrodes of DSSCs. By dipping of TiO2 layer into aqueous Na2CO3 solution, the DSSC showed a power conversion efficiency of 9.98%, compared to that (7.75%) of the reference device without surface treatment. The UV-vis absorption spectra, the impedance spectra and the dark current studies revealed that the increase of all parameters was attributed to the enhanced dye adsorption, the prolonged electron lifetime and the reduced interfacial resistance. (C) 2012 Elsevier Ltd. All rights reserved.