Influence of aminotriazole additives in electrolytic solution on dye-sensitized solar cell performance

The influence of aminotriazole additives in acetonitrile solution of an I-/I-3(-) redox electrolyte on the performance of a bis(tetrabutylammonium)cis-bis(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 10 different aminotriazole compounds. The aminotriazole additives tested had varying effects on the solar cell performance. Most of the additives enhanced the open-circuit photovoltage (V-oc), fill factor (ff) and the solar energy conversion efficiency (eta), but reduced the short circuit photocurrent density (J(sc)) of the solar cell. The highest eta of 7.6% was obtained by adding 3-amino-1H-1,2,4-triazole and eta was comparable to that of 4-t-butylpyridine (TBP). Both the physical and chemical properties of the aminotriazoles were computationally calculated in order to determine the reasons why the additive affects the solar cell performance. The greater the calculated partial charge of the nitrogen atoms in the molecule, the larger the V-oc value. The V-oc of the solar cell also increased as the size of the aminotriazole molecules decreased. The J(sc) value increased with increasing the absolute difference in the dipole moments between the calculated aminotriazoles and acetonitrile. These results suggest that the electron donicity of the aminotriazole additives influenced the interaction with the TiO2 photoelectrode and the solvent, which altered the dye-sensitized solar cell performance. (C) 2004 Elsevier B.V. All rights reserved.