Effects of TiO2 Interlayers on the Optical Switching of VO2 Thin Films Grown by Sol-Gel Process

Thermochromic VO2 and VxW1-xO2 films were deposited on TiO2/mica substrates. The TiO2/mica substrates were fabricated via Sol-Gel process, and the hydrophilicity of the TiO2/mica substrate was improved under UV light irradiated. The V2O5 sol was deposited on the TiO2/mica substrate by the spin coating method, and then it was annealed. SEM and XRD analysis were applied to analyze the morphology, phases and microstructure of the films. FTIR was used to study the thermochromic properties. The results suggest that VO2/TiO2 grow preferentially along single orientation. VxW1-xO2/TiO2 composite film is impossible to fabricate single orientation films. TiO2 interlayers are favorable to compact the VO2 thin films and reduce the transition temperature. It will make the hysteresis width of VxW1-xO2/TiO2 composite film reduce to about 4℃ particularly.