Influence of molecular weight of PEO on performance of quasi-solid-state dye-sensitized solar cells

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 (J _sc) 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 (V _oc) is observed, which is explained by the decrease in dark current arising from the reduction of triiodide (I₃ ⁻) by conduction band electrons.