Thermochromic performance enhancement by geometric structure optimization of VO2 nanoarrays for smart window application

Abstract

The localized surface plasmon resonance (LSPR) exhibited by vanadium dioxide (VO2) has expanded its utility in thermochromic smart windows. Here, guided by the absorption characteristics of a single VO2 nanoparticle (NP) with a radius between 10 to 60 nm on a glass substrate, we numerically conducted an extensive analysis of the optical properties of VO2 nano-cylinder arrays. We achieved a significant enhancement in the performance of thermochromic smart windows by optimizing the geometric structure of the VO2 arrays. Such a performance enhancement relies on the on-off switch properties of LSPR in VO2 nano-cylinder arrays. Smaller (r≤ 60) ones with high aspect ratios (> 0.75) shows a higher absorption contribution in their extinction effect and a more energetic LSPR peak located in the near-infrared spectra. Those characteristics significantly improve the thermochromic performance of smart windows via enhancing the transmission contrast between the high-temperature rutile state and the low-temperature monoclinic state of VO2. At a transmittance luminous (Tlum) efficacy of 60.03%, an excellent 20.03% in solar spectrum modulation ability (ΔTsol) can be attained. Compared to flat films with an identical Tlum, ΔTsol of the periodically cylindrical-structured film is raised by 234%.