Facile Synthesis of Island-like ZrO-VO Composite Films with Enhanced Thermochromic Performance for Smart Windows.

VO-based film, as a very promising thermochromic material for smart windows, has attracted extensive attention but has not been widely applied because it is difficult to simultaneously improve in terms of both solar-modulation efficiency (Δ) and visible transmittance () when made using the magnetron-sputtering method, and it has poor durability when made using the wet chemical method. Herein, island-like ZrO-VO composite films with improved thermochromic performance (Δ: 12.6%, : 45.0%) were created using a simple approach combining a dual magnetron-sputtering and acid-solution procedure. The film's Δ and values were increased initially and subsequently declined as the sputtering power of the ZrO target was raised from 30 W to 120 W. Δ achieved its maximum of 12.6% at 60 W, and reached its maximum of 51.1% at 90 W. This is likely the result of the interaction of two opposing effects: Some VO nanocrystals in the composite film were isolated by a few ZrO grains, and some pores could utilize their surface-plasmon-resonance effect at high temperature to absorb some near-infrared light for an enhanced Δ and . More ZrO grains means fewer VO grains in the composite film and increased film thickness, which also results in a decrease in Δ and . As a result, this work may offer a facile strategy to prepare VO-based films with high thermochromic performance and promote their application in smart windows.