Periodic micro-patterned VO2 thermochromic films by mesh printing

Abstract

VO2 has garnered much attention in recent years as a promising candidate for thermochromic window applications due to rising awareness about energy conservation. However, the trade-off between improving the luminous transmittance (Tlum) and solar modulation ability (ΔTsol) limits the commercialization of VO2-based smart windows. Four major nanostructuring approaches were implemented to enhance both Tlum and ΔTsol, namely nanocomposites, nanoporous films, biomimetic moth-eye structures and anti-reflection coating (ARC) multilayers. This work demonstrates a novel approach that fabricates periodic, micro-patterned structures of VO2 using a facile screen printing method. The micro-patterned structure is able to favorably transmit visible light without sacrificing high near-infrared modulation, and the patterned film shows improved Tlum (67% vs. 60%) and ΔTsol (8.8% vs. 6.9%) compared with continuous films. By varying the thickness, periodicity and solid concentration, this approach can give a ΔTsol of 14.9% combined with a Tlum of 43.3%, which is comparable, if not superior to, some of the best reported results found using other approaches.