Electrochromic properties of tungsten oxide (WO3) thin films on lexan (polycarbonate) substrates prepared with neon as sputter gas

Abstract

Electrochromic materials change color reversibly by applying an external DC voltage. One among the many emerging application of electrochromics is the smart windows. Tungsten oxide (WO3) is well studied and the most versatile electrochromic material. In the present communication, the tungsten oxide thin films have been prepared (at 300K) on lexan (poly carbonate) substrates by reactive DC magnetron sputtering technique using neon as sputter gas for the first time. The electrochromic performance of the WO3 thin films (in the thickness range 190 nm to 712 nm) have been studied with two aqueous electrolytes: 1M HCl and 1M Li2SO4 in a three electrode electrochemical cell. The highest coloration efficiency (at 860 nm) of the neon sputtered WO3 achieved is 273 cm2 C−1 by lithium intercalation. The inference of the present investigation is that: sputtering with neon on lexan yields tungsten oxide thin films which have high coloration efficiency, high contrast, fast coloration and are highly stable.