Fabrication of tungsten oxide-based hybrid photochromic blends by scalable method

In this paper we have synthesized tungsten oxide-based organic/inorganic hybrid materials composed of tungsten hexachloride (WCl₆) and polyvinylpyrrolidone (PVP) micro- and nanosized fibers. The films are deposited on substrates such as paper, glass, metal, and fabric using techniques including electrospinning, spin coating, fiber drawing, casting, and inkjet printing methods. The films exhibit photochromic properties at room temperature. Distinct from pure WO₃-based coatings, photochromism of the hybrid films is reversible at ambient conditions without heating or applying an electric field. Photochromic performance of the hybrid films has been studied. From optical properties studies we demonstrate about UV illumination-induced band gap engineering. Mechanism of the photochromic effect in the hybrid films is suggested to be related to defects. We suggest also that illumination with the UV light undergoes by structural point defect formation.