Characteristics of ionic adsorption on silica nanoparticles and its impact on the long term stability of dye-sensitized solar cells

Quasi-solid electrolytes based on silica nanopowder are well known in literature and these electrolytes are able to match in performance with that of liquid electrolytes. However, contrasting results are observed in literature regarding stability of dye-sensitized solar cells (DSSCs) with most of the reported articles projecting silica-loaded quasi-solid electrolyte-based cells as a stable alternative to liquid electrolyte-based cells, while a few others contradicting the same. The present study demonstrates the effect of ageing under heat (60°C) and illumination on the performance of liquid electrolyte and silica-loaded electrolyte-based DSSCs. It has been observed that DSSC based on silica-loaded electrolyte are less stable than DSSC based on liquid electrolyte even though independent study on both electrolytes by thermal analysis shows silica-loaded electrolyte to be more stable than liquid electrolyte. Segregation of silica in electrolyte has been confirmed through cryo-field emission gun-scanning electron microscopy. Zeta potential measurements show that ions are desorbed from the surface of silica on ageing under heat and illumination.