Electrochromic property of the viologen-anchored mesoporous TiO2 films

The electrochromic properties of the viologen-anchored mesoporous TiO₂ (Meso-TiO₂) films were investigated in this work. The Meso-TiO₂ films, synthesized by evaporation-induced self-assembly (EISA) process, deposited on ITO electrodes were a worm-like structure with an average pore diameter of 7.0 nm. The electrochromic devices (ECDs) fabricated from the Meso-TiO₂ demonstrated 3 times of coloration efficiency and considerably faster switching response, compared with those from the nanocrystalline films made of the 7 nm-sized TiO₂ nanoparticles. The advantage of the Meso-TiO₂ would originate from the well-organized mesopore structures, offering an efficient electrolyte transport as well as the fast electron transfer from the ITO electrode to the anchored viologen.