Improving solar modulation ability and luminous transmittance by embedding Mo nanoparticles between VO2/VO2/VO2 layers

Abstract

For decades, the improvement of the solar modulation ability (ΔTsol) without weakening the luminous transmittance (Tlum) has always been a contradiction for VO2-based smart windows. In this research, VO2/Mo/VO2/Mo/VO2 composite films were fabricated by embedding Mo nanoparticles (NPs) into VO2/VO2/VO2 tri-layer films by pulsed laser deposition. SEM characterization results suggested that Mo NPs tended to nucleate at the junctions of grain boundaries of VO2, and thus affected the morphology of the top VO2 layer. The transmission spectra of the nanoporous sample (Mo180) showed an obvious phenomenon of localized surface plasmon resonance (LSPR). As a result, the ΔTsol and Tlum of Mo180 were significantly increased to 11.6% and 55.9%, respectively. In addition, the Finite-Different Time-Domain simulation proved that the LSPR comes from the top VO2 layer of the obtained composite films rather than the Mo NPs. The particle size and spacing of VO2 grains could particularly influence the electrical field distribution of the top layer and then regulate the absorption in near-infrared region. Our present work demonstrated that non-noble Mo NPs can be used as heterogeneous nucleation sites to control the surface morphology of VO2 films, thereby achieving the purpose of controlling the thermochromic properties.