Remarkable near-infrared electrochromism of ITO@WO3 with long-term stability prepared by a facile method

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, H 2 WO 4 ·H 2 O and WO 3 nanosheets were controllably synthesized by a facile wet chemistry method. The porous ITO@WO 3 composite films are characterized by reduced impedance, enhanced charge transport, significant NIR modulation, and excellent cycling stability. When 15 wt% ITO is introduced into WO 3 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 WO 3 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 cm 2  C −1 at 633 nm and 204.73 cm 2  C −1 at 1600 nm) were achieved, showing a good application prospect in smart windows.