Performance of dye-sensitized solar cells based on ionic liquids: Effect of temperature and iodine concentration

The performance of dye-sensitized solar cells, based on pure and binary ionic liquid electrolyte with different iodine concentrations, have been evaluated under 1 sun illumination and different cells temperature between 5 and 55 degrees C. At lower temperatures a short-circuit current (J(SC)) may be c decreases limited by the diffusion of tri-iodide. In this situation J(SC) increases with increasing temperature, while at higher temperatures the J(SC) due to more pronounced recombinations. We find a maximum for J(SC) at intermediate temperatures. This maximum shifts to lower temperatures by increasing iodine concentration. At a certain temperature different iodine concentration is optimal for different ionic liquids employed in the electrolyte. The open circuit voltage monotonically decreases with temperature while the conversion efficiency is basically dominated by temperature dependence of J(SC). (c) 2007 Elsevier B.V. All rights reserved.