Thermal aging effect of vanadyl acetylacetonate precursor for deposition of VO2 thin films with thermochromic properties

• 7 day aged VO(acac)2 sol shows enhanced adhesivity on the SiO2 compared with non-aged sol.
• The aging process has significantly affected the morphologies of VO2 films.
• From the FT-IR spectra, thermal aging process provides the deformation of precursor.
• The metal insulator transition (MIT) efficiency (ΔTat2000 nm) reached a maximum value of 51% at 7 day aging.
• Thermal aging process could shorten the aging time of sol solution.

Thermochromic properties of vanadium dioxide (VO2) have been studied extensively due to their IR reflection applications in energy smart windows. In this paper, we studied the optical switching property of VO2 thin film, depending on the thermal aging time of the vanadyl acetylacetonate (VO(acac)2) precursor. We found the alteration of the IR spectra of the precursor by tuning the aging time as well as heat treatments of the precursor. An aging effect of vanadium precursor directly affects the morphologies, optical switching property and crystallinity of VO2 films. The optimum condition was achieved at the 7 day aging time with metal insulator transition (MIT) efficiency of 50%.

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