Geometrical implication of ion transporters employing an ellipsoidal hollow structure in pseudo-solid electrolytes†
We demonstrate facilitated ion transport in oligomer electrolytes by introducing TiO2 hollow particles of ellipsoidal and spherical shapes. It was found that the TiO2 hollow particles of ellipsoidal shape are much more effective in constructing ionic diffusion paths for the Grotthuss mechanism, resulting in highly enhanced diffusion coefficients of ions such as I− and I3− in oligomer electrolytes. Compared to the hollow spheres of the TiO2 component, the ellipsoidal hollow particles of the TiO2 component provide 11% larger ionic diffusion coefficients, because of their geometry with a relatively small diffusion resistance. Since the facilitated ion transport can render fast redox reactions at both photo and counter electrodes, the solid state dye-sensitized solar cells employing oligomer electrolytes based on the TiO2 hollow ellipsoids exhibit highly improved photovoltaic performances including highly improved energy-conversion efficiency without destabilizing the cell.