Synthesis and characterization of PVP-modified vanadium dioxide thin films for Smart Windows

Vanadium dioxide (VO₂) is a promising material for smart window applications due to its thermochromic behavior, which involves a reversible semiconductor-to-metal phase transition near 68 °C. However, the high transition temperature limits its practical use in building-integrated energy-saving technologies. In this study, VO₂ thin films were synthesized via the sol-gel method using vanadyl acetylacetonate as the precursor. To modify and reduce the phase transition temperature, different concentrations of polyvinylpyrrolidone (PVP) were introduced into the precursor solution. The films were deposited onto glass substrates using spin coating under varying conditions, including spin speed and annealing temperature, to optimize film uniformity and optical quality. The resulting films were characterized using Optical Microscopy, Ellipsometry, Scanning Electron Microscopy(SEM), X-ray Diffraction(XRD), and infrared (IR) spectroscopy to evaluate morphological, structural, and optical properties. The results indicate that the incorporation of PVP significantly influences the microstructure. These findings highlight the potential of PVP-modified VO₂ thin films as tunable thermochromic materials suitable for smart window applications.