Tailoring nanometric vanadium dioxide morphology to tune thermochromic optical properties

• VO 2 films and nanoparticles fabricated by fs-laser deposition and post-annealing. • Post-deposition annealing induces dewetting, forming porous films and nanoparticles. • Film morphology governs transition temperature, hysteresis symmetry, and transmittance. • Hysteresis asymmetry is linked to porosity and particle size distribution. • VO 2 nanoparticles exhibit size-dependent plasmon resonance in the NIR region. Vanadium dioxide (VO 2 ) is well known for its relatively low metal-to-insulator transition temperature, taking place at only 68 °C. Previous studies have shown that the dynamics of the phase transition are sensitive to the VO 2 morphology and nanoscale confinement, offering a promising route for tunability. This paper reports the fabrication of VO 2 thin films and nanoparticles via femtosecond pulsed-laser deposition and post-deposition rapid thermal annealing. We demonstrate the ability of this fabrication method to tune VO 2 morphology (continuous film, porous film, or individual nanoparticles). We show that these morphological changes have a significant impact on both the metal-to-insulator transition dynamics (including the transition temperature and thermal hysteresis symmetry) and the optical properties of the VO 2 as observed via visible and near-infrared transmission spectroscopy. We primarily focused on VO 2 nanoparticles revealing a correlation between their size and optical behavior. Notably, we observed that metallic VO 2 nanoparticles exhibit localized surface plasmon resonances that are sensitive to their mean diameter, with larger sizes resulting in more red-shifted peaks. By controlling the VO 2 morphology, we demonstrate the capability to tune the characteristics of the phase transition, as well as the optical and plasmonic properties, thereby broadening its applicability in nanophotonics and the development of advanced optical materials.