Electrochromic characterization of Co(OH)(2) thin film prepared by sol-gel process

Abstract

Electrochemical, spectroscopic and structural measurements were used to characterize the electrochromic behavior and stability of sol-gel deposited Co(OH)(2) thin films. These films were prepared from polymeric solutions containing cobalt methoxyethoxide precursor by spin coating technique. The as-deposited films are amorphous and show crystalline structure after heat treatment at 450 degrees C. Sol-gel-deposited cobalt hydroxide film show reversible electrochromic response in 1 M LiClO4/propylene carbonate solution beyond 500 cycles. The structural and chemical properties of the films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. Spectral transmittance change was T-p = 29.9-60.2% for cobalt hydroxide films. It is argued that reversible lithium insertion capacity, good cyclic reversibility of Co(OH)(2) films make them suitable as counterelectrode layers in the electrochromic devices. (C) 1998 Elsevier Science B.V. All rights reserved.