Crystallized TiO2 (A)–VO2 (M/R) nanocomposite films with electrochromism–thermochromism dual-response properties

Abstract

Thermochromic (TC) and electrochromic (EC) smart windows are the mostly studied categories of smart window, but they usually work in different wavebands, and each have their own advantages. This work offers a method to combine the advantages of TC and EC smart windows by synthesizing TC–EC dual-response TiO₂–VO₂ nanocomposite films. These films were prepared by dispersing VO₂ nanoparticles (NPs) in TiO₂ sols and then underwent annealing. The optimized film showed a luminous transmittance (T_lum) of 66.1% at 20 °C, 59.3% at 90 °C and a ΔT_sol of 11.2%. By applying a voltage of −5 V, the film showed an EC transmittance modulation (ΔT) of 19.1% at 630 nm, a combined performance of T_lum = 44.7% and ΔT_sol = 17.1% (increased by 52%). The color of the films could also be modified from a yellowish brown to a light blue, which is meaningful for practical usage. The current TiO₂–VO₂ nanocomposite film combines TC and EC performance, which may be an important breakthrough in energy saving smart windows.