Ru4+-assisted phase transition in VO2 nanoparticles: Electronic structures and optical properties

Abstract

VO2 is a promising thermochromic material for smart windows. The major challenge for its practical application is to strike a balance between a comfortable phase transition temperature (Tc) close to room temperature and high transmittance (T) in the visible light range. Herein, we investigated the phase transition behavior of Ru-doped VO2 using first-principles calculations. The results showed that Ru-doped VO2 can be more easily realized under O-rich conditions than under V-rich conditions. Tc is sensitive to the Ru-dopant concentration and dopant symmetry, which are related to changes in the atomic and electronic structures. Furthermore, the optical band gap for RuxV1-xO2(M) first increases and then decreases with increasing Ru content. Moreover, the switching between insulating and metallic states in RuxV1-xO2(M) can be modulated by controlling the Ru-dopant concentration, and the band gap is reduced from 0.69 eV to 0 eV with increasing Ru-dopant concentration. Additionally, Ru doping can enhance the visible and infrared light transmission (T) of VO2 materials within their very narrow energy ranges. These results provide another way to promote the thermochromic properties of VO2 for application in smart windows.