VO2/Si-Al gel nanocomposite thermochromic smart foils: Largely enhanced luminous transmittance and solar modulation

Abstract VO 2 nanoparticles with a dimension of approximately 20 nm were obtained by simple mechanical bead-milling method, which were well dispersed in transparent silica–alumina (Si–Al) gel matrix to form nanocomposites. The VO 2 /Si–Al gel thermochromic nanocomposite foils were fabricated with various VO 2 solid contents and foil thickness. With 10% VO 2 loading and 3 μm foil thickness, high luminous transmittance ( T lum(20°C)  = 63.7% and T lum(90°C)  = 54.4%), and large solar modulation ability (Δ T sol  = 12%) can be obtained which surpasses the best reported results (nanoporous films: T lum(20°C)  = 43.3%, T lum(90°C)  = 39.9% and Δ T sol  = 14.1%). This current approach provided a simple and scalable preparation method with the best combined thermochromic performance.