In this paper, redox behavior of I^－ and I₃^－ in 3-methoxypropionitrile (MePN) with different concentrations of 3-hexyl-1-methylimidazolium iodide (HMII) and iodine was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The photovoltaic performance of dye-sensitized solar cells (DSC) was compared for electrolytes containing different concentrations of HMII and iodine. The DSC with the electrolyte (1.0 mol•L^－1 HMII, 0.10 mol•L^－1 LiI, 0.12 mol•L^－1 I₂ and 0.50 mol•L^－1 4-tert-butylpyridine in MePN) gave short circuit photocurrent density J_sc of 14.06 mA•cm^－2, open circuit voltage V_oc of 0.71 V, and fill factor FF of 0.69, corresponding with the photoelectric conversion efficiency η of 6.81% under one Sun (Xenon lamp, AM1.5, 100 mW/cm²).

Key words: 3-hexyl-1-methylimidazolium iodide, redox, dye-sensitized, solar cell