Effect of aging of V2O5 sol on properties of nanoscale films

• Nanoscale V2O5 films synthesized by spin coating progressively aged sol.
• Structural and morphological changes were observed in the films.
• Loss of water of hydration resulted in decrease in interlayer spacing.
• Strain in the film decreased and conductivity increased with aging.
• Increase in transmittance and decrease in optical band gap with aging observed.

Nanoscale films having thicknesses in the range of 92 nm–137 nm were obtained by spin coating V2O5 sol at different stages of aging. The observed structural and morphological changes with time can be attributed to the reactions occurring in the sol. The film morphology changed from an indistinctive featureless film to a homogenous film having ribbon-like nanostructures with aging of sols. TGA and FTIR analysis confirmed loss in the amount of intercalated water content with aging giving rise to structural changes (decrease in interlayer spacing) which were observed using XRD. Variations in mechanical, electrical, and optical properties of the thin films were observed with aging of the sol. Strain in the films were found to decrease with aging. The electrical conductivity increased with aging and this can be correlated to the improved crystallinity of the films with aging. The optical bandgap (calculated from UV–Vis data) decreased and the transmittance increased with aging.