Effect of lanthanum doping on modulating the thermochromic properties of VO2 thin films
Lanthanum (La) doped vanadium dioxide (VO2) thin films were fabricated through a facile sol–gel technique. The La doping was found to be effective for reducing the phase transition temperature (τc) of VO2 below the 4 at% doping level, with a reducing rate of −1.1 °C per at%. In addition, below the 3 at% La doping level, the band gap (Eg) decreased steadily with the increasing addition of La dopants. 5 at% La doping can enhance both the integrated visible transmission (Tlum) and the solar modulating ability (ΔTsol) simultaneously. The combination of Tlum = 50.1% and ΔTsol = 10.3% represents the best values for VO2 continuous thin films.