Fabrication of Tungsten Oxide/Graphene Quantum Dot (WO<sub>3</sub>@GQD) Thin Films on Indium Tin Oxide-Based Glass and Flexible Substrates for the Construction of Electrochromic Devices for Smart Window Applications
Khursheed Ahmad, Gihwan Song, Haekyoung Kim
Abstract
In the present study, we have prepared tungsten trioxide (WO3)/graphene quantum dot (GQD) thin films (WO3@GQD) on indium tin oxide (ITO)-based glass and flexible (polyethylene terephthalate, PET) substrates for smart window applications. Furthermore, electrochromic devices (ECDs) were fabricated using WO3 and WO3@GQD thin films as electrochromic layers on ITO-based glass and flexible PET substrates. The WO3-based ECDs on ITO glass substrates exhibited a coloration efficiency (C.E.) of 56 cm2/C, while an improved C.E. of 78 cm2/C was obtained for WO3@GQD (5 min)-based ECDs on ITO glass substrates. The improvement in C.E. may be attributed to the presence of the conductive GQD. The WO3@GQD (5 min)-based ECDs also showed good stability for up to 10000 cycles. After checking the effect of GQD in WO3@GQD (5 min)/ITO glass through comparison with WO3/ITO glass with a liquid electrolyte, WO3@GQD (5 min) was applied for flexible ECDs. The developed flexible ECDs exhibited that WO3@GQD (5 min) can be used as a potential electrochromic layer in developing flexible smart windows.