Ether-Functionalized Pyrazolium Ionic Liquids as Electrolytes for Dye Sensitized Solar Cells

Two ether-functionalized ionic liquids (ILs) based on pyrazolium cations and bis(trifluoromethylsulfonyl)imide anions (TFSI-) as solvent and pyrazolium iodide as iodide source were first time fabricated for dye sensitized solar cells (DSSCs). The I-V characteristic curves, electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) demonstrated the performance of functionalized ILs as well as the performance of dye sensitized solar cells with the change of the concentration of iodide and iodine. It was confirmed by EIS that mass-transport limitation becoming less of a problem in the 1-(2-Methoxyethyl)-2-ethylpyrazolium (OEPZ)-based and 1-(2-Methoxyethyl)-2-methylpyrazolium (OMPZ)-based electrolytes. A maximum of 1.7% efficiency was obtained with the observed photo-voltage of 0.557V and photocurrent density of 6.3mA/cm(2) using the electrolyte concentration of 0.1M I-2 and 1M OEPZ-iodide in OEPZ-TFSI for fabrication of the solar cell without additives at 100mW/cm(2). The DSSC based on OMPZ electrolyte exhibited lower efficiency due to large resistances.