Electrochromic MoO3 thin film fabricated by using volatile MoO3(OH)2

Abstract

MoO3, one of the transition metal oxides has an attention in the industrial application fields of photochromic, electrochromic, sensor and catalyst. Among them, MoO3 thin films have been extensively investigated in the electrochromic (EC) device field due to its superior optical properties. Recently, many deposition techniques to deposit Mo oxide thin films have been developed including chemical vapor deposition (CVD), evaporation, sol-gel coating, RF magnetron sputtering, and pulsed laser deposition (PLD). In this study, homogeneous MoO2 thin films was successfully deposited by the chemical vapor transport (CVT) of MoO3(OH)2 during the reduction of MoO3 powder in H2 and MoO3 thin film was subsequently obtained by thermal annealing. As annealing commenced, the optical transmittance of the films increased due to enhancement of the crystallinity resulted from oxygen vacancy reduction and increase of the relative density from reduction of porosity. Also, the annealed MoO3 thin film was intercalated by ions in the electrolyte as LiClO4 dissolved in propylene carbonate (PC) and electrochromic property of the film was analyzed.