Novel cyclotetrasiloxane tetraimidazolium salts as high performance quasi-solid state electrolyte for dye-sensitized solar cells

A new type of quasi-state ionics based on cyclosiloxane imidazolium iodides was synthesized and used as electrolytes in dye-sensitized solar cells (DSSCs). The cyclosiloxane electrolyte formed a distinctive cavity in the center of the molecule, and the cyclic Si-O linkages were surrounded with bulky tetraimidazolium salts on the outside. The resulting electrolytes were characterized by 1 H nuclear magnetic resonance (NMR) spectroscopy and thermogravimetric analysis (TGA). The electrolytes exhibited dark brown quasi-solid state, high viscosity, and excellent long term stability. The cell efficiency tended to depend on the chain length of the electrolyte, and was slightly higher in the propylimidazolium electrolyte (η max =8.2%) than in the methylimidazolium one. The superior long-term stability of the fabricated, cyclosiloxane electrolyte-based DSSCs demonstrated that they hold great promise in overcoming the current issues affecting on cell performance.