The influence of aminothiazole additives in acetonitrile solution of an I-/I-3(-) redox electrolyte on the performance of a bis(tetrabutylammonium)cis-is(thiocyanato) bis(2,2'- bipyridine-4-carboxylic acid, 4-carboxylate)ruthenium(II) (N719) dye-sensitized TiO2, solar cell was studied. The current-voltage characteristics were investigated under AM 1.5 (100 mW/cm(2)) for nine different aminothiazole compounds. The aminothiazole additives tested had varying influences on the solar cell performance. Most of the additives enhanced the open-circuit photovoltage (V-oc), but reduced the short circuit photocurrent density (J(sc)) of the solar cell. Both the physical and chemical properties of the aminothiazoles were computationally calculated in order to determine the reasons that the additive influenced solar cell performance. The larger the calculated partial charge of the nitrogen atom in the thiazole, the higher the V, value. The V., value increased as the dipole moment of aminothiazoles in acetonitrile increased. Moreover, the Voc of the solar cell also increased as the size of the aminothiazole molecules decreased. These results suggest that the electron donicity of the aminothiazole additives influenced the interaction with the TiO2 photoelec-trode, which altered the dye-sensitized solar cell performance. (C) 2004 Elsevier B.V. All rights reserved.