Morphology-Dependent Near-Infrared Electrochromic Properties of Tungsten Oxide

Vertically aligned WO3 nano-architectures on the transparent conducting substrate are produced via a hydrothermal method. The results revealed that different WO3 nano-architectures, including “nanoblocks”, “nanosheet” and “nanobelt” structures, can be obtained by adjusting the composition of the precursor solution, that shows that solvent composition plays an important role in the adjustment of the prepared material morphology. The nanostructured array films with thicknesses of about 600 nm show remarkable enhancement of the electrochromic properties in the infrared region. The obtained WO3 films have good electrochromic properties in the near-infrared range. In particular, significant optical modulation of the WO3 nanosheets (72% at 1200 nm), fast switching speed (6.5 s for colored and 8.7 s for bleached), and excellent cycling stability (maintained 90.2% of the initial optical modulation after 1000 cycles). The improved electrochromic performance is mainly due to the vertically arranged structure, which makes it easier for ions to diffuse in the nanoarray, and also provides a larger surface area for charge transfer reaction. The research results provide a certain reference value for the research of electrochromic near-infrared performance