Enhanced electrochromic performance of 2D grid-structured WO3 thin films

Controlling the microstructure of Tungsten trioxide (WO3) film is believed to be an efficient strategy to enhance its electrochromic (EC) performance in recent years. Here, WO3 thin films with two-dimensional (2D) grid structure are fabricated through electrodeposition using polystyrene (PS) nanofibers as sacrificial templates. The surface of WO3 thin films has grooves formed by the removal of PS nanofibers and thus the films are divided into grid structure. Due to the larger specific surface area and lower diffusion impedance induced by the grid structure, these WO3 films demonstrate an obvious enhancement of EC performance compared with the plane WO3 thin films obtained using the same electrodeposition parameters in the absent of PS nanofibers templates. The transmittance modulation rate (Delta T) of the grid-structured WO3 thin films is over 50% larger than that of the plane WO3 films at the wavelength of 550 nm. Consequently, the grid-structured WO3 films have a higher coloration efficiency (71.8 cm(2)/C) compared with the plane WO3 films (58.8 cm(2)/C). Furthermore, the coloration/bleaching time of grid-structured WO3 films are 1.27/0.93 s, which is much shorter than the plane WO3 films (2.34/2.18 s). The grid-structured WO3 films in this work show potential applications in the construction of highly performance and rapidly responsive EC devices.