New ionic liquids based on siloxane diimidazolium iodides (SiDII1, SiDII2, SiDII3) were synthesized and used as electrolytes in dye-sensitized solar cells. Modification with siloxane materials has been considered as the most effective method to improve the excellent optical transparency and thermal stability after a great many efforts. The synthesized siloxane diimidazolium iodides are viscous liquid with different color. These electrolytes have different chain length with siloxane moieties. Thermogravimetric analysis showed good thermal stability. Among the three SiDII based electrolytes, SiDII1 showed a maximum photo-conversion efficiency of 6.2%. In addition, the performance of the DSSCs showed relatively reasonable compared with other conventional liquid type electrolytes. (C) 2013 Elsevier Ltd. All rights reserved.