Electrodeposited Vanadium Dioxide Films with Unique Optical Property

This study represents a facile but effective electrodeposition method to fabricate vanadium dioxide (VO₂) thin films on fluorine doped tin oxide (FTO) glass at room temperature. The film microstructure (thickness, surface structure, particle size and composition) and relevant optical properties were investigated by several advanced techniques. The pertinent variables that can affect the thin film formation and structure, such as deposition potential, time and post-treatment annealing temperature were also studied. It was found that the film thickness could be tuned from 35 to 130 nm by adjusting the potential from −1.22 to −1.35 V, and consequently leading to optical transmittance decreasing from ∼60% to ∼38% in the wavelength of 500–1000 nm, further confirmed by computational simulations using three-dimension (3D) finite-difference time-domain method. The hysteresis loop of the generated VO₂ film on FTO glass shows that the phase transition temperature from monoclinic to rutile is around 73 °C, a little higher than pure monoclinic VO₂ (∼68 °C) in this study. This proposed electrodeposition method is possible to extend into obtaining metal oxide films with tuneable surface properties for thermochromic smart devices.