Optimizing phase transition temperature and visible transmittance of VO₂ films driven by synergistic effect of La-Mo co-doping

Optimizing the metal–insulator transition temperature (θ_MIT) and optical switching behavior of vanadium dioxide (VO₂) is desirable for boosting thermochromic applications. Ions co-doping engineering has been proved a powerful method in improving the comprehensive performance of VO₂. Here, the La-Mo co-doped VO₂ films are fabricated on c-cut sapphire substrate by a hydrothermal method. In the case of constant Mo concentration (1.5 at.%), it is found that the increased La dopants contribute to synchronously achieve the reduction of θ_MIT from 60 °C @ 0 at.% La to 38 °C @ 1 at.% La and the improvement of visible light transmittance. The reduced θ_MIT along with enhanced luminous transmittance is attributed to the La-Mo co-doping synergetic effect, which effectively reduces the band gap between the V 3d_|| and π* band and broadens the band gap between the O 2p and π* band.