Optical and electrical properties of thermochromic VO2 thin film combined with Au or Zr-containing compounds nanoparticles

Abstract

In this study, we investigate the influence of metal-based nanoparticles (NPs), namely Au and ZrN, on the optical and electrical characteristics of thermochromic vanadium dioxide (VO2) thin films. Au NPs are prepared by wet chemistry-based methods and are chemically bonded to the VO2 surface via organic linkers, while ZrN NPs are synthesized by gas aggregation technique and deposited on the VO2 layer, eventually leading to the formation of additional Zr-containing compounds (e.g., nitrides, oxides and/or oxynitrides). Two configurations were then investigated: i) NPs deposited on the VO2 surface and ii) NPs embedded inside the VO2 layer. The combination of Au or ZrN NPs with the VO2 surface results in enhanced infrared light modulation, attributed to anti-reflection effects induced by the presence of the NPs layer on the VO2 surface. On the other hand, the average metal-toinsulator transition temperature is significantly reduced down to 35.5 ◦C when Au NPs are embedded in the VO2 layer. This is attributed to electron-doping effects and confirmed by the resistivity and optical measurements. Finally, analysis of optical performance parameters such as solar energy modulation, infrared transmittance and luminous transmittance in the visible range provides insights into the overall capabilities of these materials for smart window applications. Furthermore, stability assessments show consistent results over temperature cycles, highlighting the reliability of these nanocomposite platforms. This study introduces a dualconfiguration approach to modulate the thermochromic response of VO2 using metal-based nanoparticles, revealing a clear structure–property relationship depending on NP placement and composition.