Cs_xWO₃ nanoparticles were dispersed in prepolymerized methyl methacrylate (PMMA) and filled in nanopores of delignified wood to prepare transparent wood. The wood-based composite showed excellent near-infrared (NIR, ranging from 780 to 2500 nm) shielding ability and high visible light transparency. The Cs_xWO₃/transparent wood also showed excellent mechanical properties with a fracture strength up to 59.8 MPa and modulus up to 2.72 GPa. Cs_xWO₃/transparent wood is expected to serve as a potential material for smart-window applications.

F-doped VO₂ (M1) nanoparticles were prepared via one-pot hydrothermal synthesis. The F-doping can minimise the size of the VO₂ (M1) nanoparticles, induce a homogeneous size distribution and effectively decrease the phase transition temperature to 35 °C at 2.93% F in VO₂. VO₂ smart glass foils obtained by casting these nanoparticles exhibit excellent thermochromism in the near-infrared region, which suggests that these foils can be used for energy-efficient glass. Compared to a pure VO₂ foil, the 2.93% F-doped VO₂ foil exhibits an increased solar-heat shielding ability (35.1%) and a modified comfortable colour, while still retaining an excellent solar modulation ability (10.7%) and an appropriate visible transmittance (48.7%). The F-doped VO₂ foils are the first to simultaneously meet the requirements of a reduced phase transition temperature, diluted colour and excellent thermochromic properties, and these properties make the further improved F-doped VO₂ foils suitable for commercial applications in energy efficient glass.

The Mott phase transition compound vanadium dioxide (VO₂) shows promise as a thermochromic smart material for the improvement of energy efficiency and comfort in a number of applications. However, the use of VO₂ has been restricted by its low visible transmittance (T_vis) and limited solar modulation ability (ΔT_sol). Many efforts have been made to improve both of these limitations, but progress towards the optimization of one aspect has always come at the expense of the other. This paper reports that Ti doping results in the improvement of both the T_vis and ΔT_sol of VO₂-nanoparticle-derived flexible foils to the best levels yet reported. Compared with an undoped VO₂ foil, a 15% increase (from 46.1% to 53%) in T_vis and a 28% increase (from 13.4% to 17.2%) in ΔT_sol are achieved at a Ti doping level of 1.1%, representing the best performance reported for similar foils or films prepared using various methods. Only a defined doping level of less than 3% is beneficial for simultaneous improvement in T_vis and ΔT_sol. First principle calculations suggest that an increase in the intrinsic band gap of VO₂ (M) and the reduced electron density at Fermi level of VO₂ (R) cooperate to result in the improvement of ΔT_sol and that an enhancement in the optical band gap of VO₂ (M) leads to the increase of T_vis.