The improvement of bilayer VO2/TaOx thermochromic properties for smart window

In this paper, the bilayer VO2/TaOx structure was investigated to control the solar spectra with the potential application as smart windows in built environments. The VO2 film was prepared by rapid thermal annealing of the sputtered vanadium thin film on the plain glass substrate. Then the TaOx as the antireflection layer was deposited by reactive magnetron sputtering on the top of the VO2 thin film. The films were characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy and UV-VIS-NIR spectrophotometry. The VO2 thin film was well-crystallized and the TaOx layer did not change the preferred growth orientation of VO2. The deposition of the TaOx film formed a denser morphology, resulting in reduced surface roughness. The VO2/TaOx bilayer could markedly boost the solar regulation efficiency (Delta T-sol) from 6.27 to 12.12% and possesses excellent luminous transmittance (T-lum = 46.12%). The phase transition temperature for the VO2 thin film and the bilayer VO2/TaOx were 58 degrees C and 56 degrees C, respectively, far below 68 degrees C of bulky VO2. The study results provide inspiration for the application of VO2 in the field of smart windows.

Automated summary

This paper investigates the bilayer VO2/TaOx structure for controlling solar spectra in the potential application of smart windows. The study finds that the VO2 thin film and TaOx layer exhibit excellent crystallinity and surface properties, and the bilayer structure significantly enhances solar regulation efficiency while maintaining good luminous transmittance.