Dye-sensitized solar cells (DSSCs) have attracted much attention since the first report written by O' Regan and Grätzel [1] in 1991 due to their simple preparation procedure, low-cost, environmental compatibility and good performance under diffuse light conditions. To date, the highest solar cell efficiency has reached 13 % [2-3] using liquid electrolytes. However, liquid electolytes possess challenges for practical applications such as leakage and volatilization, packaging problem and toxicity [3-4].