Synthesis of high-performance electrochromic thin films by a low-cost method

Abstract Metal-doping is an effective method to adjust the physical and chemical properties of semiconductor metal oxides. This work adopts a simple solvothermal method to synthesize Mo-doped tungsten oxide nanoparticles. The high-performance electrochromic films can be homogenously formed on ITO glass without post-annealing. Compared with pure WO3 films, the optimized Mo-doped WO3 films show improved electrochromic properties with significant optical contrast (68.3% at 633 nm), the short response time (6.3 s and 3.9 s for coloring and bleaching, respectively), and excellent coloration efficiency (107.2 cm2 C-1). The improved electrochromic behavior is mainly due to the increasing diffusion rate of Li+ in Mo-doped WO3 films (increased 20% than that of pure WO3 films). The porous surface of Mo-doped WO3 film shortens the diffusion path of Li+. Besides, Mo doping reduces the resistance and improves conductivity. Furthermore, 2at% Mo-doped WO3 films indicate satisfactory energy-storage properties (the specific capacitance is 73.8 F g-1), resulting from the enhanced electrochemical activity and fast electrical conductivity. This work presents a practical and economical way of developing high-performance active materials for bifunctional electrochromic devices.