Visualization of ultraviolet irradiation using WO3-cellulose derivatives composite film

Abstract Tungsten oxide (WO3) based photochromic films consisting of methyl cellulose (MC), hydroxyethyl cellulose, carboxymethyl cellulose (CMC) or cellulose nanofiber (CNF) are fabricated for monitoring ultraviolet (UV) light. The opaque WO3/MC film becomes transparent by adding ethylene glycol (EG) whereas the WO3/CMC and WO3/CNF are transparent without EG. The WO3/EG/MC film possesses much higher sensitivity to the UV light than the WO3/CNF film. Visually, the blue color of the WO3/CNF film after UV irradiation for 8 h is almost equivalent to that of the WO3/EG/MC film after irradiation for 1 min. The color change of the WO3/CNF and the WO3/EG/MC film can be used to monitor UV from the sun light. We also demonstrated that the WO3/EG/MC film can be used to measure the UV intensity quantitatively up to 6 mW cm−2.