Long-term investigation of unsealed DSSCs with glycerol-based electrolytes of different compositions

Long-term stability belongs to the main problems of dye-sensitized solar cells (DSSCs), impeding their practical application. Especially the usually fluid electrolyte tends to evaporation, thus drying the cells if they are not perfectly sealed. While gelling the electrolyte with different polymers often reduces the efficiency, using a glycerol-based electrolyte was already shown to result in similar or even improved efficiency. At the same time, drying of the cells was significantly reduced. Here we report on improving glycerol-based electrolytes further by varying the iodine-triiodide ratio and the overall concentration in the electrolyte. Long-term tests with unsealed glass-based DSSCs were performed over more than 1 year, showing that most of the cells increased efficiency during this time, opposite to cells with a commercial solvent-based iodine-triiodide electrolyte which completely dried after 2–3 months.