Novel Nano-Structured Silica-Based Electrolytes Containing Quaternary Ammonium Iodide Moieties

A series of new hybrid organic-inorganic molecules were prepared either by grafting of aminopropyltriethoxysilane (APTS) on silica nanoparticles followed by quaternarization of the nitrogen with ethyl, heptyl and isopropyl iodides or by grafting of N,N,N-triethyl-3-(triethoxysilyl)propan-1-aminium iodide and N,N,N-tridodecyl-3-(triethoxysilyl)propan-1-aminium iodide onto the silica nanoparticles. These new materials were used as iodide sources in the preparation of electrolyte solutions for dye-sensitized solar cells (DSSCs). The performance of DSSCs was studied as a function of the nature of the solvent, the nature of the dye, the concentration of the modified silica in the electrolyte system and the silica content introduced during the hybrid synthesis. An efficiency of 8.5 % was obtained for solar cells containing the triethyl ammonium iodide salt at a concentration of 1 M in either acetonitrile (AN) or 3-methoxypropionitrile (MPN) under an illumination of 10 mW cm-2, the equivalent of 0.1 Sun at AM 1.5G. At 1 Sun (100 mW cm-2, efficiencies of 6.6 % and 5.1 % were recorded for the AN and MPN-based electrolytes, respectively.