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 (T_lum) and solar modulation ability (ΔT_sol) limits the commercialization of VO₂-based smart windows. Four major nanostructuring approaches were implemented to enhance both T_lum and ΔT_sol, 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 T_lum (67% vs. 60%) and ΔT_sol (8.8% vs. 6.9%) compared with continuous films. By varying the thickness, periodicity and solid concentration, this approach can give a ΔT_sol of 14.9% combined with a T_lum of 43.3%, which is comparable, if not superior to, some of the best reported results found using other approaches.