Nanobrick-like WO3 thin films: Hydrothermal synthesis and electrochromic application

• Nanobricks WO3 thin films synthesized by hydrothermal method.
• WO3 thin films exhibit good optical modulation and fast switching kinetics.
• Provides maximum 39.24 cm2/C coloration efficiency for nanobricks.
• Color luminance is analyzed by CIE 1931 chromaticity diagram.

Nanobrick-like WO3 thin films have been synthesized via facile hydrothermal route. Nanostructured WO3 thin films were characterized using X-ray diffraction (XRD), UV–Vis–NIR spectrophotometer, scanning electron microscopy (SEM), atomic force microscopy (AFM) to investigate the intentional properties such as phase structure, optical properties and surface morphology. Moreover electrochromic (EC) performance of WO3 thin film was investigated in 0.5 M LiClO4/PC by means of cyclic voltammetry (CV), chronocoulometry (CC) and chronoamperometry (CA). The value of diffusion coefficient (D) was determined from anodic peak current and was found to be 1.51 × 10−9 cm2/s. The response time of 6.9 s for bleaching (tb) and 9.7 s for coloration (tc) was observed with excellent reversibility 76%. The coloration efficiency for nanobricks WO3 is 39.24 cm2/C. CIE 1931 L∗ab values for colored and bleached films were estimated at 2° observer using D-65 illumination. The electrochromic studies show highly reversible and the stable nature of WO3 thin film which provides a versatile and promising application towards the fabrication of smart windows.

Schematic formation of WO3 thin film and Optical transmittance spectra in colored and bleached state.Figure optionsDownload as PowerPoint slide