Nanoporous Thermochromic VO2 Films with Low Optical Constants, Enhanced Luminous Transmittance and Thermochropnic Properties

摘要

Nanoporous thermochromic VO2 films with low optical constants and tunable thicknesses have been prepared by polymer-assisted deposition. The film porosity and thickness change the interference relationship of light reflected from the film-substrate and the air-film interfaces, strongly influencing the optical properties of these VO2 films. Our optimized single-layered VO2 films exhibit high integrated luminous transmittance (T_(lum,1) - 43.3%, T_(lum,h) -39.9%) and solar modulation (△T_(sol) = 14.1%, from T_(sol,1) = 42.9% to T_(sol,h) = 28.8%), which are comparable to those of five-layered TiO2/VO2/TiO2/VO2/TiO2 films (T_(lum,1) = 45%, T_(lum,h) = 42% and △T_(sol) = 12%, from T_(sol,1) = 52% to T_(sol,h) = 40%, from Phys. Status Solidi A 2009, 206, 2155-2160.). Optical calculations suggest that the performance could be further improved by increasing the porosity.