ELECTROCHROMIC CHARACTERIZATION OF CO(OH)(2) THIN-FILM PREPARED BY SOL-GEL PROCESS

Electrochemical, spectroscopic and structural measurements were used t o characterize the electrochromic behavior and stability of sol-gel de posited 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 cob alt hydroxide film show reversible electrochromic response in 1 M LiCl O4/propylene carbonate solution beyond 500 cycles. The structural and chemical properties of the films were investigated by X-ray diffractio n, X-ray photoelectron spectroscopy and scanning electron microscopy. Spectral transmittance change was T-p = 29.9-60.2% for cobalt hydroxid e films. It is argued that reversible lithium insertion capacity, good cyclic reversibility of Co(OH)(2) films make them suitable as counter electrode layers in the electrochromic devices. (C) 1998 Elsevier Scie nce B.V. All rights reserved.