Studies on the Electrochromic Behavior of Lithium and Proton Based Solid State Devices

Abstract

In the present investigation, two types of DC magnetron sputtered tungsten oxide (WO3) solid state electrochromic devices: one with lithium and the other using protons as intercalating ions have been prepared and analyzed. The lithium based device consisting of lithium aluminum fluoride (electrolyte ~ 500nm) and vanadium oxide (storage layer ~100 nm) has color/bleach cycle of about 10s and the transmittance variation of 40%. The proton device consisting of: Ta2O5 (electrolyte ~300nm) and NiOx (storage layer ~100nm) has a coloration time of few milliseconds and the transmittance variation is about 60%; the top electrode for these devices is semitransparent gold of thickness 10nm. The stability of the proton device has been found to be quite satisfactory for thermal cycling and X-ray dosage of 11.7R. The change in contact potential difference of WO3 during coloration has been measured using Kelvin probe technique for the first time to understand the electrochromic behavior.