Thermochromic VO2 films for energy-efficient windows

Abstract VO 2 films were produced by reactive e-beam evaporation followed by annealing post-treatment. Electrical measurements demonstrated a semiconductor-metal transition at τ c ∼ 60° C . Spectrophotometry showed that the near-infrared solar transmittance was reduced when τ c was exceeded while the luminous transmittance remained relatively unchanged. This thermochromism may be utilized for regulating the energy throughput of windows. Practical application hinges on improved transmittance and on τ c - depression . These goals can be accomplished to some extent by dielectric overlayers, as verified by measurements on SiO 2 -coated VO 2 films.