Tuning thermochromic performance of VOx-based multilayer films by controlling annealing pressure

Abstract In this work, the nominal SiNx/NiCr/NiCrOx/VOx/NiCrOx/NiCr/SiNx multilayer films deposited on glass were obtained by magnetron sputtering and subsequent rapid thermal annealing (RTA) in N2 at 0.5–2000Pa pressure. Annealing pressure influenced the radiation thermal resistance, which can directly determine the crystallization and thermochromic performance of the VOx-based multilayer films. The VO2 (M) film is very difficult to form under low annealing pressure because of insufficient oxygen and low-valence metal oxides in NiCrOx film. Therefore, the thermochromic performance is seriously deteriorated by the drastic diffusion between NiCrOx and VOx. Based on the phase transition temperature (Tc) and good crystallization, the wider process window of 80 Pa–300 Pa has been obtained successfully. Additionally, the films exhibit the optimal thermochromic performance with the solar regulation (ΔTsol) of 18.4% and the luminous transmittance (Tlum) of 40.5%. Moreover, the Tc can be reduced to 54 °C by regulating annealing pressure without element doping. The results provide guidance for commercial production and quality consistency of VOx-based smart glass in building energy conservation.