High performance dye-sensitized solar cells containing 1-methyl-3-propyl imidazolinium iodide-effect of additives and solvents

In this work, the influences of redox electrolyte, additives and solvents on the photovoltaic performance of dye-sensitized solar cells (DSSCs) containing 1-methyl-3-propyl-imidazolinium iodide (MPII) as the electrolyte were investigated. An optimum conductivity of 20.31 mS cm^-1 for 0.6 M MPII in acetonitrile (AN) was found out from the conductivity measurement. Diffusion coefficient of I₃^- and photocurrent density (J_SC) of the DSSC varied with concentration of I₂. Among the different inorganic and organic iodides as additives, the DSSC showed high performance with lithium iodide (LiI) and tetrabutylammonium iodide (TBAI), respectively. The performance of the DSSCs with different solvents was studied. From the EIS studies, it was inferred that the poor conversion efficiencies of the DSSCs were associated with high charge transfer resistance, noted along the TiO₂/solvent interface. A high conversion efficiency of 6.7% (J_SC of 14.8 mA cm^-2, V_OC of 0.74 V, fill factor (FF) 0.62 under one sun (AM 1.5)) was obtained for the DSSC containing the electrolyte composition of 0.6 M of MPII/0.2 M of LiI/0.06 M of I₂/0.5 M of TBP in AN along with the incorporation of light scattering particles (TiO₂ of 300 nm).