High productivity and purity alkyl cyclic sulfonium iodides were prepared by using autoclave and water/ethyl acetate system. Autoclave synthesis took shorter time (about 1/3 of traditional method) guaranteeing against productivity decline, and the extraction with water/ethyl acetate system took shorter purifying time as well as avoiding the use of poisoned organic solvents. These alkyl cyclic sulfonium iodides were used as iodide source to prepare electrolytes for dye-sensitized solar cell (DSC). The efficiency of corresponding DSC based on these sulfonium iodides was near to that based on imidazole iodide. The result of electrochemical impedance spectra showed that the sulfonium cation could inhibit the back reaction within DSC and be benefit for electron exchange reaction on counter electrode compared with imidazole cation, resulting in higher open voltage and better fill factor.

Key words: dye-sensitized solar cell, sulfonium iodide, autoclave, synthesis