Doped TiO2 semiconductor powders were synthesized using Al and W as photovoltaic property-enhancing impurities. Al-doped TiO2 electrodes increased open-circuit voltage (V-OC), but reduced short-circuit current (I-SC). In contrast, W-doped TiO2 had an opposite effect. However, dye-sensitized solar cell efficiency fabricated with doped TiO2 was remarkably better than that of undoped TiO2. It seems that these phenomena were related to electrical surface-state modifications induced by metal-ion dopants. These modifications led to significant changes in powder aggregation, charge transfer kinetics, and dye adsorption characteristics. The highest efficiency was found by using (Al + W)-doped TiO2 nanopowders. (C) 2004 Elsevier Inc. All rights reserved.