The effect of lithiation on the electrochromism of sol-gel derived niobium oxide films

Niobium oxide films are promising cathodic electrochromic materials that in certain aspects can compete with the more frequently studied WO3 films. The films reported here were prepared using the sol-gel route from a NbCl5 precursor. The electrochromic properties were pronounced for crystalline films heat-treated at 500 degrees C exhibiting transmittance changes between the colored and bleached states of 60% in the ultraviolet (UV) and 80% in the visible and near-infrared spectral regions. The reversibility of electrochromic changes of thick niobium oxide films (d > 250 nm) was enhanced by lithiation.