Quasi-solid-state dye-sensitized solar cells （DSCs） were prepared using gel electrolyte gelated by poly（ethylene-oxide） （PEO） with different molecular weight. With the increase in PEO molecular weight, the short circuit current densities （Jsc） increase significantly, which is related to the increase in I - diffusion due to the increase in free volume of gel electrolyte. However, only a slight increase in open voltage （Voc） is observed, which is explained by the decrease in dark current arising from the reduction of triiodide （I3^-） by conduction band electrons.
