Fabrication of Photochromic Tungsten Oxide Based Composite Film Using Peroxoisopolytungstic Acid

Abstract Tungsten-based photochromic composite films were fabricated using peroxoisopolytungstic acid aqueous solution and transparent urethane resin. UV–visible irradiation of the resulting composite films showed photochromic properties, indicating broad absorption with peaks at 650 and 900 nm. The coloring time was about 40 min. The colored composite films were transformed to clear film in a dark room in 90 h.