Enhanced electrochromic performance of highly ordered, macroporous WO3 arrays electrodeposited using polystyrene colloidal crystals as template

• Macroporous bowl-like WO3 array film is prepared by electrodeposition using PS spheres template.
• High coloration efficiency of 68 cm2 C−1 are obtained for the bowl-like WO3 array film.
• The bowl-like WO3 array film exhibits fast switching speed of 3.6 s (coloration) and 1.0 s (bleaching).

Periodical bowl-like macroporous WO3 array film was electrodeposited on ITO glasses using self-assembled monolayer polystyrene (PS) spheres as template. The film showed a connected network of close-packed hemisphere pores (microbowl arrays) with average size of 600 nm after the template was removed. The structure of the film revealed by XRD and TEM was that nanocrystals embedded into an amorphous matrix. The electrochromic property of the WO3 microbowl array film was examined in 0.5 M H2SO4 solution. Compared with dense film prepared without PS template, the WO3 microbowl array film showed superior electrochromic property with coloration efficiency of 68 cm2 C−1, response times of 3.6 s (coloration) and 1.0 s (bleaching), and without significant change in cyclic stability.