Multi-component eutectic salts to enhance the conductivity of solvent-free ionic liquid electrolytes for dye-sensitized solar cells

Abstract

Ionic liquids (ILs) possess intrinsic nonvolatility, low flammability, high ionic conductivity, high thermal and chemical stability, rendering themselves as excellent candidates for next generation dye-sensitized solar cells (DSSCs). Further improving the ionic conductivity of ionic liquid electrolytes is critical to the performance enhancement of DSSCs. Here, multi-component eutectic salts by mixing four ILs are proposed to achieve higher ionic conductivity compared to the individual one. In addition, the effect of mixing strategy on the eutectic salts was systematically investigated by diverse structural, thermal, electrochemical and photovoltaic characterization in detailed. It revealed that mixing strategy could not only tune the solid-state property of individual ILs to liquid-state eutectic salts, but also greatly improve the ionic conductivity of final multi-component eutectic salts. Thus, based on the multi-component eutectic salt, a power conversion efficiency (PCE) of 4.81% could be obtained by the resultant device. Moreover, the DSSCs with multi-component eutectic salt also display better stability than the referenced device with volatile organic solvent. The mixing eutectic salts offer us a feasible strategy to design high ionic conductive electrolytes for high performance dye-sensitized solar cells.