Cylindrical model of electrochromic colouration of hydrated vanadium pentoxide thin films with point contacts

Abstract

This article analyses experiments on the kinetics of the internal electrochromism of thin (micron) films of hydrated vanadium pentoxide xerogel with point contacts. It describes a cylindrical model of electrochromic colouration, which was used to evaluate the concentration of the colour centres in the initial film and after additional hydrogenation of this film by plasmaimmersion ion implantation.When we compared the calculated values of the concentration of colour centres with the equilibrium concentration of protons in the xerogel, we saw that the mobility of the protons migrating from the depth of the film to the cathode region, which are involved in the electrochemical reaction, was not a determinant of the electrochromism kinetics.The rate of electrochromic colouration could be increased by the formation of layered film structures based on hydrated vanadium pentoxide, which have increased overall electron conductivity and, as a consequence, low faradaic resistance of the electrochromic cathodic reaction.