Modulation of the metal-insulator transition in VO2 nanoparticles with nRu+W (n=1–4) codoping: Implications for energy-saving smart windows

Abstract

Vanadium dioxide (VO2), a remarkably popular thermochromic material, has attracted considerable attention due to its unique reversible metal-insulator phase transition characteristic, which can be used in practical applications such as energy-saving smart windows. However, the advance on enhancing the visible light transmittance while obtaining a useable phase transition temperature remains unresolved issue. Herein, the atomic structures and electronic-optical properties of nRu+W-codoped (n =1–4) VO2 were investigated by the first-principles calculations. The results show that the nRu + W-codoped VO2 is thermally and mechanically stable. The desirable nRu + W co-doped VO2 can be easily prepared under V-rich conditions, and that some V atoms were replaced by Ru and W atoms in the codoping structures, with the [RuO6] and [WO6] octahedra cosharing an edge or oxygen atoms. Furthermore, a lower phase transition temperature and the near-infrared modulation capacity of VO2 could be obtained in theoretical calculations due to the synergistic effect of nRu+W codoping. That is, the introduction of Ru atoms could widen the optical band gap of VO2, increasing the luminous transmittance; Simultaneously, the Fermi levels for nRu+W configurations gradually entered one of the narrow bands, decreasing the electronic band gap and further reducing the phase transition temperature due to the incorporation of the W dopant, which donates extra electrons to the codoping systems due to its higher ion valence. The current work provides an approach for improving the thermochromic performance of VO2 films in energy-saving smart windows, thereby providing new insights into the relationship between overall performance improvement and structural variations induced by elements codoping.