Near-infrared-activated VO2 based nanothermochromic smart windows by incorporation of photothermal W18O49 nanorods

Abstract

VO2-based thermochromic smart windows have attracted much attention due to their promising energy-saving effects. However, the high phase transition temperature (Tc, 68 °C), low luminous transmittance (Tlum, <40%) and solar energy modulation efficiency (ΔTsol, <10%) hindered their practical application. In order to improve these deficiencies simultaneously, the photothermal W18O49 nanorods were introduced into VO2 based nanothermochromic films in this work. The obtained film exhibited enhanced thermochromic performance (Tlum = 82.5%, ΔTsol = 10%) due to the incorporation of W18O49 nanorods. And Tlum of 63.3% and ΔTsol of 18.6% were presented for the bilayer film, which is one of the best reported performances for VO2 films to date. In particular, the bilayer film exhibited an obvious energy saving effect with a reduction of 21.1 °C in indoor temperature compared with normal glass due to its excellent thermochromic properties. In addition, the thermochromic characteristics of VO2-W18O49-polyvinylpyrrolidone (PVP) composite films could be trigged at lower temperature than that of VO2 film due to the additional thermal energy generated by the absorption of near-infrared light by W18O49 nanorods. Therefore, the outstanding performance and the easily scaled solution-based synthesis route would facilitate the practical application of VO2-based smart windows.