Perfluoro anion based binary and ternary ionic liquids as electrolytes for dye-sensitized solar cells

In this work, eight new ionic liquids (ILs) based on triethylammonium (TEA) or n-methylpiperidinium (NMP) cations and perfluoro carboxylate (PFC) anions having different carbon chain lengths are synthesized and their physico-chemical properties such as density, decomposition temperature, viscosity and conductivity are determined. Photovoltaic characteristics of dye-sensitized solar cells (DSSCs) with binary ionic liquids electrolytes, containing the mixture of the synthesized ILs and 1-methyl-3-propyl imidazolium iodide (PMII) (v/v = 35/65), are evaluated. Among the different ILs, solar cells containing NMP based ILs show higher VOC than that of TEA, whereas, higher JSC is noted for the DSSCs incorporated with the latter when compared to the former. Further, the photo-current of the DSSCs decreases with the increase of the carbon chain length of perfluoro carboxylate anionic group of ILs. The cell performance of the DSSC containing ternary ionic liquids-based electrolytes compose of NMP-2C/TEA-2C/PMII (v/v/v = 28/7/65) exhibits a JSC of 12.99 mA cm−2, a VOC of 639.0 mV, a FF of 0.72, and a cell efficiency of 6.01%. The extraordinary durability of the DSSC containing the above combination of electrolytes stored in dark at 50 °C is proved to be unfailing up to 1200 h. [Display omitted] •Eight triethylammonium and n-methylpiperidinium cations based ILs are synthesized.•The ILs have different carbon chain lengths of perfluoro carboxylate anions (PFC).•The cell efficiency decreases with the increase of the carbon chain length of PFC.•DSSC with ternary IL as electrolyte shows an efficiency of 6.01%.•It shows an unfailing long-term stability up to 1200 h stored in dark at 50 °C.