Hydrothermal synthesis of WO3 nanoflowers on etched ITO and their electrochromic properties

Abstract Herein, we present, for a first time, an electrochromic film of WO 3 fabricated on an ITO by wet etching process using hydrochloric acid (HCl). A low-cost, facile and template-free hydrothermal method adopted with a simplified architecture where etching process supports WO 3 to form an adhesive layer. The X-ray photoelectron spectroscopy was used to study the surface composition of the films. Electrochemical impedance spectroscopy (EIS) was employed to reveal the charge transfer process at the interface with the help of Randles circuit model. Compared to before etched WO 3 configuration, the etched WO 3 configuration exhibited a strong enhancement in terms of roughness, porosity, open-tunnel structure, current density, coloration efficiency (about 178.7 cm 2  C −1 ) and faster response time. Moreover, electro-optical characterization illustrates high transmittance modulation (about 49% at 630 nm) with excellent stability, making it attractive for a practical application.