Remarkable Near-Infrared Electrochromism of Ito@Wo3 with Long-Term Stability Prepared by a Facile Method

Abstract

Near-infrared (NIR) electrochromism are one of the most attractive candidates for solar heat regulation, photodynamic therapy, optical telecommunications, and military camouflage. However, complex preparation process, non-ohmic contact within electrochromic nanomaterials or with substrates, and inferior electrochromic performance limit the massive application of electrochromic devices (ECD). Herein, ITO nanocrystals, H2WO4·H2O and WO3 nanosheets were controllable synthesized by a facile wet chemistry method. Porous ITO@WO3 composite films feature reduced impedance, improved charge transport, remarkable NIR modulation and high cycling stability. When 15 wt.% ITO is introduced into WO3 nanosheet, the composite film possesses the optimal ΔT (62% at 1600 nm) at a low voltage of +0.3 V to -0.3 V, the bleaching time (25.4 s) is greatly improved than that of pure WO3 film (38.1 s), and the optical modulation retains 93% of the original values after 5000 cycles. Moreover, an impressive dual-band ECD with high optical modulation (53.4% at 633 nm and 49.3% at 1600 nm) and high coloration efficiencies (125.27 cm2 C-1 at 633 nm and 204.73 cm2 C-1 at 1600 nm) was achieved, showing a good application prospect in smart windows.

Keywords: Electrochromism, Near-infrared light, WO3 nanosheet, ITO nanocrystal, Composite film