Electrochemical properties of dye-sensitized solar cells fabricated with PVDF-type polymeric solid electrolytes

We have already proposed a poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP)-based polymeric solid electrolyte (PSE) film for dye-sensitized solar cells (DSSCs). The employment of the PSE film, however, almost always accompanies with decrease in short-circuit current density (J _sc). We then studied electrochemical properties on the PSE-based and liquid electrolyte-based DSSCs to clarify the reason why the conversion efficiency is lower in the former than in the latter. The diffusion coefficient of I₃ ^- and the cell gap of DSSCs were found out to play a key role to increase J _sc. In particular, the stronger cell-gap dependence was observed in the PSE-based DSSC than in the liquid electrolyte-based DSSC. This indicates that the design of DSSC structure is quite important to achieve the higher conversion efficiency in the PSE-based DSSC. We confirmed that the J _sc of a PSE-based DSSC with a 20 μm cell gap is turned out to be about 97% of the J _sc of a liquid electrolyte-based DSSC.