Simulation of smart windows in the ZnO/VO2/ZnS sandwiched structure with improved thermochromic properties

We modeled a sandwiched structure ZnO/VO2/ZnS potentially as a VO2-based smart window with a goal to increase both luminous transmittance (Tlum) and solar modulation ability (ΔTsol). Compared to the previously used single-layer antireflection coating, the new sandwiched structure broadens the reflectance minimum in the visible light range and enlarges the transmission gap in the near-infrared (NIR) region, when switching between the semiconducting and the metallic states and when utilizing an intermediate index ZnS layer imbedded between the VO2 film and substrate. The 3/4-1/4-3/4 wavelength-thickness model exhibited a high solar modulation ability (ΔTsol = 13.01%), and maintained a high Tlum at 63.24% and 57.39% both in semiconducting and metallic phases, respectively.