In the present work, the effect and the mechanism of the interaction between 1-methylbenzimidazole (MBI) with Li+ and TiO2 on the performance of dye-sensitized solar cells were explored. A negative shift of the TiO2 Fermi level of the nanostructured TiO2 electrode could attribute to the interaction of MBI with Li+ and TiO2, which shown that MBI affects the surface state of the TiO2 film by decreasing the amount of the adsorbed Li+ ions. When MBI was added in the electrolyte, the interfacial exchange current density (j(0)) reduced and the cathodic Tafel slope (beta(c)) increased in dye-sensitized solar cells due to the reduction of the surface adsorption of Li+ and I-3(-) ions from the electrolyte. The photovoltaic performance of the dye-sensitized solar cells under UV illumination suggests that the addition of MBI in the electrolyte could improve the efficient and stability of dye-sensitized solar cells. (C) 2008 Elsevier Ltd. All rights reserved.