Preparation and characterization of VO2–BaSO4 composite films with enhanced optical properties in thermochromic field

Abstract The application of VO 2 for smart windows relies on the enhancement in both luminous transmittance ( T lum ) and solar modulating ability (Δ T sol ). Achieving a sufficiently high T lum with satisfactory Δ T sol remains to be a challenge. In this article, VO 2 –BaSO 4 composites were prepared by a one-step hydrothermal process and the coated films using these powders showed increased T lum (from 30.4% to 43.5%) and Δ T sol (from 11.2% to 12.4%). The optimized optical properties could match with those of the five-layered TiO 2 /VO 2 /TiO 2 /VO 2 /TiO 2 films ( T lum,l =45%, T lum,h =42% and Δ T sol =12%, from Phys. Status Solidi A 2009, 206, 2155–2160). The BaSO 4 could also reduce the degradation of the optical performance for the W-doped VO 2 composite film. After doping 1.0 at% W, the Δ T sol value of the pure VO 2 film deteriorated to 4.9% with T lum,h =28.2%, while the VO 2 –BaSO 4 composite film could retain a relatively high Δ T sol of 6.5% and an obviously increased T lum of 47.4%. The BaSO 4 nanoparticles could improve the T lum and Δ T sol of the VO 2 films simultaneously.

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