Electrochromic multilayer films with enhanced stability based on polyoxometalate and TiO2

Electrochromic multilayer films consisting of polyoxometalate (POM) cluster K6[P2W18]·14H2O (P2W18), TiO2 and polyallylamine hydrochloride (PAH) were fabricated on quartz, silicon wafer and ITO substrates by the layer-by-layer self-assembly method. The multilayer films were characterized by UV–vis spectrum, scanning electron microscopy (SEM), cyclic voltammetry (CV) and chronoamperometric (CA) and in situ spectral electrochemical measurements. The interesting feature is that the electrochromic films can increase stability due to the presence of TiO2. The multilayer films exhibit high optical contrast, suitable response time and low operation potential. TiO2 is employed to enhance stability of the electrochromic multilayer films based on POMs by the layer-by-layer method, which gives valuable information for exploring new stable electrochromic materials.