Novel warm/cool-tone switchable VO2-based smart window composite films with excellent optical performance

Vanadium dioxide (VO2) is a key material for thermochromic smart windows that can respond to environmental temperature to regulate near-infrared transmittance automatically. To date, VO2-based smart windows have made great progress, but practical applications still remain restricted by two tough challenges, i.e., low solar regulation ability and unpopular color. In view of the above two challenges, in this paper, novel warm/cool-tone switchable VO2-based composite films were designed and prepared. The novel composite films demonstrate outstanding optical properties: ΔTsol = 18.92% and Tlum,l = 48.70%. The high solar modulation efficiency is attributed to the modulation of the thermochromic microcapsules in visible light waveband and VO2 in near-infrared region. Meanwhile changes in color of the composite films at different temperatures were also studied in order to develop high-performance warm/cool-tone switchable thermochromic smart windows. These promising results will benefit to promote the popularization and application of smart windows.