Electrochromic properties of cobalt-doped titanium dioxide films

Titanium dioxide (TiO 2 ) has been widely studied as an inexpensive and efficient electrochromic material. However, slow response speed and poor cycling performance still constrain the further application of TiO 2 electrochromic materials. In this work, a series of cobalt-doped TiO 2 electrochromic films were fabricated via hydrothermal method combined with a spin-coated approach. The effects of doped cobalt ions on the electrochemical and electrochromic performance of TiO 2 were explored. The cobalt-doping concentrations on the morphology and electrochromic performance of the samples were investigated by means of XRD, XPS, FESEM, HR-TEM, and electrochemical techniques. It is found that the ionic diffusion coefficient of the 0.5% Co-TiO 2 composite film is 6.44 × 10 −10 cm 2 /s, the coloring efficiency is 34.11 cm 2 /C, and the coloring and bleaching switching time are 1.92 s and 10.71 s, respectively. Moreover, the 0.5% and 1% Co-TiO 2 composite films showed superior cyclic performance than pristine TiO 2 . This indicates that the appropriate amount of Co doping can significantly enhance the electrochromic properties of titanium dioxide films.