Facile sol–gel fabrication of MoS2 bulk, flake and quantum dot for electrochromic device and their enhanced performance with WO3

Abstract

Low–temperature fabrication of electrochromic device (ECD) is an attractive characteristic, supporting their use in smart windows and flexible devices. In this study, different MoS2 morphologies (bulk, flake and quantum dots) are fabricated onto indium tin oxide using the sol–gel method. The ECD performance of the fabricated MoS2 devices is optimized, and then the MoS2 bulk, flake and quantum dots are used as electrochromic anodic layers, with WO3 as cathodic layer to prepare MoS2/WO3–based ECDs. The fabricated MoS2/WO3 ECDs are found to exhibit high optical contrasts (59–75%) at 1.5–0 V and 700 nm. In addition, the stability, switching time and coloration efficiency of the MoS2 devices are found to be improved by the WO3 layer. When MoS2 quantum dot film is used as an electrochromic layer, it shows better ECD performance with WO3 than films prepared with either bulk or flake MoS2. It could be expected that the MoS2 quantum dot morphology allows more Li+ ions to penetrate the crystal lattice, promoting a greater charge transfer, which is crucial for the enhanced electrochromic property. This work provides an encouraging support for the application of cost effective, solution–processed MoS2/WO3–based ECDs, working at low temperature and low voltage, to the processing of flexible and optical devices.