The potential of eutectic mixtures as environmentally friendly, solvent-free electrolytes for dye-sensitized solar cells

A new kind of solvent-free eutectic melt electrolytes for dye-sensitized solar cells (DSCs) has been designed, which are composed of imidazolium salts (i.e. 1-methyl-3-acetylimidazolium iodide (MAII), 1-ethyl-3-methylimidazolium iodide (EMII)) and plastic crystal succinonitrile (SN). Differential scanning calorimetric measurement reveals that the eutectic melt mixture EMII/SN can exhibit stable liquid state in the whole temperature domain from −80 to 80 °C. Besides, the conductivities of the eutectic melt electrolytes are higher than conventional imidazolium-based ionic liquid, 1-propyl-3-methylimidazolium iodide (PMII). Up to 7.46% of light-to-electricity conversion efficiency has been achieved by using the SN-based eutectic melt electrolyte, higher than PMII-based DSCs. Besides, the devices based on eutectic melt electrolytes exhibit good thermal stability. These results show that succinonitrile-based eutectic melts as environmentally friendly electrolytes, possess great potential for large-scale outdoor application of DSCs.