WO 3 -based electrochromic enhancement via porous ZnO:Ga nanorods prepared by a two-step hydrothermal process

Abstract This study demonstrates the enhancement on electrochromic properties of the WO 3 /ZnO through the use of Ga 3+ -doped ZnO nanorods synthesized via a two-step hydrothermal process. The granular-surfaced WO 3 /ZnO:Ga nanorods provided a larger effective surface area for redox reactions, leading to improved light extraction that increases with Ga 3+ concentration. Compared with the WO 3 /ZnO nanorods, the WO 3 /ZnO:Ga nanorods exhibited faster coloration and bleaching responses, with switching times reduced from 7.0 s to 5.8 s and from 2.7 s to 1.9 s, respectively. In addition, a coloration efficiency of 34.58 cm 2 C −1 was achieved at a wavelength of 650 nm. The electrochromic stability was also significantly improved, with anodic and cathodic current retentions enhanced by 91.7% and 15.8%, respectively, indicating higher charge preservation over repeated redox cycles.