Nanosized multilayer films with concurrent photochromism and electrochromism based on Dawson-type polyoxometalate

An inorganic–organic composite multilayer film constructed of poly(vinyl alcohol) (PVA) with Dawson-type phosphotungstate anion [P2W18O62]6− (P2W18) and poly(allylamine hydrochloride) (PAH) were fabricated on quartz, ITO, silicon and CaF2 substrates by a layer-by-layer self-assembly method. The film was provided with concurrent photochromism and electrochromism. IR spectra showed that the structure of the PVA was fully maintained in the multilayer film. And their photochromic and electrochromic properties were investigated by UV–vis spectra, cyclic voltammetry (CV), chronoamperometry (CA) measurement and X-ray photoelectron spectra (XPS). Atomic force microscopy (AFM) was used to investigate the surface topography. This study provides a new route to explore the possibility of application to polyoxometalate-based hybrid inorganic–organic materials.