Enhancing visible-light transmittance while reducing phase transition temperature of VO2 by Hf–W co-doping

Abstract

In order to enhance the visible-light transmittance while reducing the insulator–metal transition (IMT) temperature, Hf–W co-doping is designed for modification of VO2. We grow high-quality HfxWyV1−x−yO2 (HfWVO2) alloy films on c-plane sapphire substrates by pulsed laser deposition, and test structural, electrical, and optical properties of the films by various techniques. The Hf–W co-doped VO2 films exhibit outstanding thermochromic performances with a high luminous transmittance up to 41.1%, a fairly good near-infrared modulation capacity of 13.1%, and a low phase transition temperature of 38.9 °C. The enhanced luminous transmittance along with reduced IMT temperature in HfWVO2 is attributed to the co-doping synergetic effect of Hf and W, which effectively improves the optical bandgap and donates extra electrons into the system, respectively, while largely retaining the near-infrared modulation capacity of VO2. Our work provides an effective strategy in tailoring VO2 toward practical smart-coating applications by Hf–W co-doping.