Controlled dissolution of polystyrene nanobeads: Transition from liquid electrolyte to gel electrolyte

The widespread commercialization of dye-sensitized solar cells (DSSCs) remains limited because of the use of highly volatile liquid electrolytes. Recently, gel-type quasi-solid electrolytes containing a polymer additive or inorganic nanomaterial have shown promising results in terms of the cell efficiency. However, most gel electrolytes have serious obstacles for pore-filling because of their high viscosity. Herein, we report the first observation of the transition from a liquid to a gel electrolyte after filling the cell with the liquid electrolyte using the controlled dissolution of polystyrene nanobeads on the counter electrode, suggesting that the pore-filling problem can be diminished in quasi-solid state DSSCs. The time-resolved solidification allows for the preparation of the gel electrolyte without interfering with the cell performance. The optimal DSSC composed of the gel electrolyte exhibits almost the same power conversion efficiency as the liquid electrolyte based DSSC when measured using an AM1.5G solar simulator at 100 mW/cm ² light illumination. Moreover, the long-term stability of the DSSC was greatly improved.