Latent gel electrolyte precursors for quasi-solid dye sensitized solar cells: The comparison of nano-particle cross-linkers with polymer cross-linkers

New latent gel electrolyte precursors (Precursor 1) consisting of ionic liquids and latent gelators are reported. The gelators are composed of poly(vinylpyridine) (PVP) and di-carboxylic acids. Gelation is caused by the reaction between PVP and di-carboxylic acid. Precursor 1 is liquid and is injected into cells and porous TiO2 electrodes. Because of the latent properties, the viscosity of Precursor 1 does not increase at room temperature. After the Precursor 1 is injected into cells and into porous TiO2 layers, the cell is heated at 90 °C. Solidification occurs swiftly. The latent mechanism is discussed. The trend of photo-voltaic performance for the cell filled with Precursor 1 before and after gelation was compared with that for the cell filled with previously reported latent gel electrolyte Precursor 2 composed of nano-particles and di-carobxylic acids. Photo-voltaic performance for the former decreased after quasi-solidification, but the latter did not. This is explained by insufficient phase-separations of gelator backbone from ionic liquid electrolytes after solidification.