Enhanced Electrochromic Properties of Ir-Ta Oxide Grown Using a Cosputtering System

The authors deposited iridium tantalum oxide thin films using the reactive cosputtering system. The prepared IrTaOx thin films were characterized using X-ray photoelectron spectroscopy, transmission electron microscopy, chronocoloumetry, in situ transmittance measurements, and electrochemical impedance spectroscopy. The oxidized iridium in IrTaOx was increased by increasing the composition of tantalum. Most of IrTaOx thin films have high transmittance modulation, which is attributed by the proton conductivity of tantalum. As a result, the Ir33Ta67 oxide thin film shows a performance of 1.4 s of response time, 5 x 10(-9) cm(2)/s of ion diffusion coefficient, and 20 cm(2)/C of coloration coefficient. The enhanced IrTaOx thin films are expected to be candidate of electrochromic materials for fast response time. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3425616] All rights reserved.