Influence of incorporated particles on the optical performance of VO2 nanoparticle-based thermochromic films

Vanadium dioxide (VO₂) nanoparticle-based thermochromic films are widely used in smart windows because of their favorable thermochromic and optical properties. The introduction of additional particles into VO₂ NP-based films enables the integration of their properties with those of the original films. This combination serves to modulate the optical performance of the films further. However, the impact of the incorporated particles on the optical performance of VO₂ NP-based thermochromic films has not been elucidated. In this study, the influence of particles with varying refractive indices, volume fractions, and sizes, when incorporated into VO₂ NP-based films, was calculated using the finite-difference time-domain (FDTD) method. The results indicate that an increase in the refractive index or the size of the incorporated particles led to an enhanced solar modulation ability (ΔT_sol), albeit at the cost of reducing the luminous transmittance (T_lum). Conversely, increasing the volume fraction of the particles did not significantly enhance the ΔT_sol. Additionally, the introduction of additional particles into the film further reduces the total energy consumption by a maximum of 2.6 MJ/m² compared to VO₂ NP-based films, according to EnergyPlus software analysis. Our findings offer new perspectives and recommendations for the development and practical implementation of thermochromic smart windows.