Electrical transport properties of [(1 - )succinonitrile:poly(ethylene oxide)]-LiCFSO-Co[tris-(2,2'-bipyridine)](TFSI)-Co[tris-(2,2'-bipyridine)](TFSI) solid redox mediators.

A solid redox mediator (solid electrolyte) with an electrical conductivity () greater than 10 S cm is an essential requirement for a dye-sensitized solar cell in the harsh weather of Gulf countries. This paper reports the electrical properties of solid redox mediators prepared using highly dissociable ionic salts: Cotris-(2,2'-bipyridine), Cotris-(2,2'-bipyridine), and LiCFSO as a source of Co, Co, and Li ions, respectively, in a solid matrix: [(1 - )succinonitrile:poly(ethylene oxide)], where = 0, 0.5, and 1 in weight fraction. In the presence of large size of cations (Co and Co) and large-sized and weakly-coordinated anions (TFSI and CFSO), only the succinonitrile-poly(ethylene oxide) blend ( = 0.5) resulted in highly conductive amorphous regions with of 4.7 × 10 S cm for EO/Li = 108.4 and 3.1 × 10 S cm for EO/Li = 216.8. These values are slightly lower than 1.5 × 10 S cm for = 0 and higher than 6.3 × 10 S cm for = 1. Only blend-based electrolytes exhibited a downward curve in the log - plot, a low value of pseudo-activation energy (0.06 eV), a high degree of transparency, and high thermal stability, making it useful for device applications.