Preparation And Performance Study Of TaO_x/VO₂（Ta） Composite Films For Smart Windows

In recent years,the issue of energy consumption in buildings related to economic development and the natural environment has attracted a great deal of attention.Smart windows with VO₂ film as the functional layer can dynamically control the transmittance of the near-infrared band according to the ambient temperature to reduce energy consumption and make the room have a comfortable environment of“warm in winter and cool in summer”,which has become an intelligent window with much attention.However,the large-scale application of VO₂-based smart windows still faces many challenges,mainly in:（1）luminous transmittance and solar regulation efficiency are inefficient and mutually sacrificial.（2）The transition temperature is much higher than the critical temperature for human thermal sensing.（3）VO₂ is easily oxidized and loses its modulation ability.（4）The preparation process is complicated and unsuitable for large-scale industrial production.Based on the above bottlenecks,this paper optimizes and investigates the thermochromic performance of the VO₂ functional layer,which is mainly as follows:（1）This paper first discusses the multi-dimensional effects of TaO_x films on the optical properties of VO₂.TaO_x films can be used not only as a reflection layer to increase the luminous transmittance by 30.06%and obtain nearly double the solar regulation efficiency but also as a smoothing layer to reduce the inherent roughness of VO₂ surface.It is also used as a protective layer to prevent VO₂ from losing its regulation efficiency due to oxidation in the air.（2）In order to reduce the transition temperature down to the critical temperature for human thermal sensing,Ta is used in this paper to achieve uniform doping of VO₂ films.In a certain range with the increase of Ta doping content,the crystalline quality of VO₂ films slightly decreases and the grain size of the surface decreases.The absorption edge of samples is obviously blue-shifted and the optical band gap is widened,resulting in a slight increase in luminous transmittance.When the doping concentration is up to 4.38 wt%,the transition temperature of VO₂（Ta）film decreases to 29.87℃ and there is almost no thermal hysteresis.（3）Subsequently,the synergic effect of the antireflection layer and element doping on the thermochromic performance of VO₂ was investigated.TaO_x/VO₂（Ta）composite films were prepared to obtain a smart window with high luminous transmission rate,appropriate transformation temperature and excellent response consistency.In summary,the TaO_x/VO₂（Ta）composite film prepared and researched in this paper provides a convenient process method and an effective research idea for the development of green energy-saving thermochromic smart windows and has certain application prospects.