Photo-switching and conductive properties of polymeric deep eutectic solvent-based tungsten oxide–zinc oxide nanocomposites

The photo-switching of inorganic functional materials is receiving serious attention as smart materials for many applications. Herein, a mixture of tungsten oxide/zinc oxide nanocomposites was facilely prepared using a polymeric deep eutectic solvent comprising of polyethylene glycol and thiourea in the presence of different organic acids: glacial acetic acid (GA), itaconic acid (ITA) and lactic acid (LA). The morphological characteristics of the nanocomposites revealed spherical and ovoidal-shaped particles with slight agglomeration. Further, the photo-switching response of the nanocomposites revealed a blue colouration after exposure to UV light for at least 90 s, with visible-light-induced electronic absorptions at 777, 772 and 628 nm for the GA-, ITA- and LA-based nanocomposites, respectively. Based on electrochemical impedance spectroscopy studies, the ITA-based nanocomposites demonstrated a wide broadband which depicts good conductivity of the material. The observed fast photo-switching and conductivity properties show prospects for preparing materials for application in photochromic smart glasses/windows, optical display and semiconducting devices.