Room temperature molten salt 1-methyl-3-（trimethylsilyl）methyl-imidazolium iodide （MSII） was used for io-dide sources in dye-sensitized solar cells with an organic sensitizer 2-cyano-3-[5-[4-[3-[4-（4-（N,N-bis（4-methoxy-phenyl）amino）phenyl）phenyl]-2,5-di-n-butyl-pyrrolo[3,4-c]pyrrole-1,4-dione]phenyl] furan-2-yl] acrylic acid （DPP-I） as light harvester. With an optimized electrolyte （MSII ： I2 ： BI ： GuNCS=24 ： 2 ： 2 ： 0.4, BI and GuCNS are short for benzimidazole and guanidine thiocyanate, respectively）, photovoltaic parameters （Jsc, Voc, and ff） of device are 8.97 mA·cm^-2, 600 mV and 0.61, respectively, yielding a maximum overall photo-to-energy con-version efficiency （17） of 3.23%. And then the charge-transfer mechanism of devices was deeply analyzed with elec- trochemical impedance spectroscopy （EIS） in the dark.
