Influence of 1-methyl-3-propylimidazolium iodide on I3−/I− redox behavior and photovoltaic performance of dye-sensitized solar cells

In this paper, we investigated redox behavior of I− and I3− in 3-methoxypropionitrile (MePN) with different concentrations of 1-methyl-3-propylimidazolium iodide (MPII) and iodine by cyclic voltammetry and electrochemical impedance spectroscopy. It was found that the apparent diffusion coefficient (D) values of triiodide and iodide ions, the serial resistance (Rs) and the charge-transfer resistance (Rct) decreased slightly with increase of the concentration of I3− in MePN containing 1.4 M MPII. Moreover, the Rct and D values of triiodide and iodide ions affection on dye-sensitized solar cells (DSCs) should be considered as a whole. The DSCs with the electrolyte (1.4 M MPII, 0.1 M LiI, 0.1 M I2, 0.5 M TBP, in MePN) gave short circuit photocurrent density (Jsc) of 14.44 mA/cm2, open circuit voltage (Voc) of 0.72 V, and fill factor (FF) of 0.69, corresponding to the photoelectric conversion efficiency (η) of 7.17% under one Sun (AM1.5).