Designed growth of WO3/PEDOT core/shell hybrid nanorod arrays with modulated electrochromic properties

Designed growth of tungsten oxide (WO3)/poly(3,4-ethylenedioxythiophene) (PEDOT) core/shell hybrid nanorod arrays has been obtained by combining solvothermal and in situ electropolymerization techniques. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and Raman characterization results indicate that the hybrid nanorods are composed of single crystalline WO3 nanocores wrapped by thin amorphous PEDOT nanoshells. The hybrid nanorods exhibit promising electrochromic performance of much shorter response time (3.8 s for coloring and 3.6 s for bleaching) than the bare WO3 nanorods (12.4 s for coloring and 7.6 s for bleaching), while the optical contrast of the hybrid nanorods increases from 26% of PEDOT to 72% in 633 nm. And the coloring efficiency and stability of the core/shell hybrid nanorods are also enhanced compared to the individual components. Dynamic analysis suggests a synergistic effect between the WO3 nanocore and the PEDOT nanoshell. In addition, color depth and optical contrast of the hybrid nanorods can be modulated by adjusting the applied voltage and the deposition of the PEDOT nanoshell. The hybrid nanorod films obtained by the cost-effective wet chemical methods may find promising applications in energy-saving windows, smart displays as well as other energy efficient technologies.