Electrochromic properties of nanocrystalline MoO3 thin films

Electrochromic MoO3 thin films were prepared by a sol-gel spin-coating technique. The spin-coated films were initially amorphous; they were calcined, producing nanocrystalline MoO3 thin films. The effects of annealing temperatures ranging from 100 degrees C to 500 degrees C were investigated. The electrochemical and electrochromic properties of the films were measured by cyclic voltammetry and by in-situ optical transmittance techniques in 1 M LiClO4/propylene carbonate electrolyte. Experimental results showed that the transmittance of MoO3 thin films heat-treated at 350 degrees C varied from 80% to 35% at lambda = 550 nm (Delta T = similar to 45%) and from 86% to 21% at lambda >= 700 nm (Delta T = similar to 65%) after coloration. Films heat-treated at 350 degrees C exhibited the best electrochromic properties in the present study. (C) 2007 Elsevier B.V. All rights reserved.