ELECTROCHROMISM OF SOL-GEL DERIVED NIOBIUM OXIDE-FILMS

Niobium oxide films are promising cathodic electrochromics that in man y aspects can compete with the more frequently studied WO3 films. The films reported herein were prepared using the sol-gel route from a NbC l5 precursor. The electrochromic properties were pronounced for crysta lline films that are heat-treated at 500 degrees C and exhibited trans mittance changes between coloured and bleached states of 60 % in the U V and 80 % in the VIS-NIR regions. Improved bleaching and more reversi ble electrochromism of thick niobium oxide films (d > 250 nm) were obt ained by lithiation.