Enhanced electrochromic properties of donor–acceptor polymers via TiO2 composite

Abstract Titanium dioxide (TiO 2 ) nano-rod thin film was successfully synthesized via hydrothermal method on fluorine doped tinoxide (FTO) coated transparent conductive glass substrate. Then, three donor-acceptor polymers based on 2, 1, 3-benzothiadiazole or perylenediimide have been electropolymerized on TiO 2 nano-film to form organic-inorganic hybrid films. XRD, FTIR and SEM characterizations confirm the coupling of polymer and TiO 2 nano-film, and the hybrid films present loose and porous morphology. After investigating the electrochromic properties of these hybrid films, the results indicate that the composite films display similar optical absorption with the pure polymer films, while improved switching response and stability of these hybrid films have been achieved. These improved electrochromic properties can be attributed to the formation of the donor-acceptor system, and loose, porous morphology of the nanocomposite, which will induce fast ion diffusion and provide large surface area for charge–transfer reactions.