N,S co-doping of VO2 films with enhancing luminous transmittance and investigation of phase transition

Vanadium dioxide (VO2), known for its phase transition properties, is a promising candidate for thermochromic applications. However, its high phase transition temperature and low visible light transmittance restrict its applicability. To overcome these challenges, we propose a co-doping strategy in this study. Using a simple annealing technique, we synthesize N,S co-doped VO2 films that exhibit phase transition at ambient temperature. Optical evaluations reveal a substantial improvement, with a 24.3 % increase in luminous transmittance for the co-doped films compared to undoped VO2 films. Furthermore, we conducted first-principles calculations to investigate the effects of S and N dopants on the electronic structure of VO2, offering valuable insights into how these dopants influence the phase transition process. These results offer an alternative approach to enhance the optical properties of VO2 and contribute to a deeper understanding of its phase transition mechanisms.