Electrochromic thin films of tungsten oxide have been prepared on a flexibl
e substrate by the sol-gel method. A solution of WOCl4/(PrOH)-Pr-i was used
as precursor. Films were synthesized by dip-coating on commercially availa
ble PET (polyethylene terephtalate)/ITO (indium tin oxide) substrates. Owin
g to the ITO sensitivity to acid attack, no pure WO3 coating could have bee
n obtained. Some ITO grains separate during the dip-coating process leading
to a mixture of WO3 and ITO. Coatings surface and morphology was studied b
y scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy.
Composition in depth was investigated by SEM pictures of cross-section and
by secondary ions mass spectroscopy. The electrochromic properties of these
films (area = 25 cm(2)) were analyzed in a three-electrodes cell with a 1
M LiClO4/propylene carbonate electrolyte. Though the structure is not yet f
ully understood, these coatings exhibit good electrochromic properties. (C)
2001 Elsevier Science Ltd. All rights reserved.