Niobium oxide films are promising cathodic electrochromics that in many aspects can compete with the more frequently studied WO3 films. The films reported herein were prepared using the sol-gel route from a NbCl5 precursor. The electrochromic properties were pronounced for crystalline films that are heat-treated at 500oC and exhibited transmittance changes between coloured and bleached states of 60 % in the UV and 80 % in the VIS-NIR regions. Improved bleaching and more reversible electrochromism of thick niobium oxide films (d > 250 nm) were obtained by lithiation.

Niobium oxide films are promising cathodic electrochromics that in many aspects can compete with the more frequently studied WO3 films. The films reported herein were prepared using the sol-gel route from a NbCl5 precursor. The electrochromic properties were pronounced for crystalline films that are heat-treated at 500oC and exhibited transmittance changes between coloured and bleached states of 60 % in the UV and 80 % in the VIS-NIR regions. Improved bleaching and more reversible electrochromism of thick niobium oxide films (d > 250 nm) were obtained by lithiation.