Electrochromic behavior of CVD molybdenum oxide and Mo-W mixed-oxide thin films

Abstract

Thin films of molybdenum oxide, tungsten oxide, and mixed Mo-W oxide were prepared by atmospheric-pressure chemical vapor deposition. For all films, the technological conditions were kept constant. Mixed oxides are expected to exhibit superior electrochromic properties compared to the pure components, because of more intensive electron transfers between W and Mo states of different valence, or between one and the same metal state but with different structural disordering. The electrochromic characteristics were studied with the help of the cyclic-voltammetric technique. All films showed stabilized current–voltage (C–V) responses and good durability. The electrolyte used was LiClO₄+propylene carbonate. All films showed an electrochromic effect. Coloration as a result of Li intercalation was observed. For the as-deposited as well as the annealed mixed-oxide films, the current density was considerably larger than for pure metal oxide films. The electrochromic behavior was studied as a function of the annealing temperature.