Influence of electrolytes on the photovoltaic performance of organic dye-sensitized nanocrystalline TiO2 solar cells

We have studied the influence of electrolytes on the photovoltaic performance of mercurochrome-sensitized nanocrystalline TiO2 solar cells using LiI, LiBr, and tetraalkylammonium iodides as the electrolyte. Short-circuit photocurrent density (J(sc)) and open-circuit photovoltage (V-oc) depended strongly on the electrolyte. J(sc) of 3.42 mA cm(-2) and V-ov of 0.52 V were obtained for the LiI electrolyte and J(sc) of 2.10 mA cm(-2) and V-oc of 0.86 V were obtained for the Pr4NI electrolyte. This difference in photovoltaic performance was due to the change in the conduction band level of the TiO2 electrode. Large V-oc of 0.99V was obtained for the LiBr electrolyte due to the large energy gap between the conduction band level of TiO2 and the Br/Br-2 redox potential. Solar cell performance also depended strongly on organic solvent, suggesting that the physical properties of solvents such as Li ion conductivity and donor number affect photovoltaic performance. (C) 2001 Elsevier Science B.V. All rights reserved.