Effect of hydrogenation on the optical properties and internal electrochromism in vanadium pentoxide xerogel films

The paper describes the effect of hydrogenation of vanadium pentoxide thin films by plasma-immersion ion implantation on their composition, optical properties, and the internal electrochromic (IEC) effect. Variations in the composition and structure caused by the hydrogen insertion, as well as those caused by the electrochromic effect, are studied by nuclear magnetic resonance, thermogravimetry, Raman spectroscopy, and X-ray structural analysis. It is shown that, during electrochromic coloration, if the cathode is located on the non-hydrogenated region of the film, and the anode is on the hydrogenated region, the IEC effect is more pronounced. This is due to the fact that the migration of protons from the region enriched with hydrogen is considerably greater than that from the pristine non-hydrogenated region. Thus, the ion implantation-induced hydrogenation can substantially enhance the manifestation and performance of the IEC effect in V2O5 xerogel films. Particularly, the rate of coloration increases by 2-3 times after ion-implantation-assisted hydrogenation as compared to that in the as-prepared non-hydrogenated films.