Assembling Tungsten Oxide Hydrate Nanocrystal Colloids Formed by Laser Ablation in Liquid into Fast-Response Electrochromic Films

High-performance electrochromic films based on tungsten oxide hydrate ([WO2(O-2)H2O]center dot 1.66H(2)O) colloidal nanocrystals with fast switching speed were fabricated by laser ablation in a mixture of water and hydrogen peroxide followed by electrophoretic methods. Through electrophoretic deposition, the nanoparticles in the colloids synthesized by laser ablation aggregated onto the FTO coated glass substrate forming a lager cell with a uniform size of around 2OO nm, which subsequently self -assembled into a porous tungsten oxide hydrate film. By optimizing the electrophoretic time (800 s) and voltage (-0.5 V), the mesh -like porous tungsten oxide hydrate film achieved a wide optical modulation of 32% at 632 nm, fast coloration and bleaching response speed of 7.8 s and 1.7 s respectively due to the synergetic effect of the unique atomic structure of [WO2(O-2)H2O]center dot 1.66H(2)O and porous structure with large surface area that facilitates the ion insertion/extraction. Thus the tungsten oxide hydrate can be a promising electrochromic material for practical applications. (C) 2016 Elsevier Inc. All rights reserved.