Energy exchange potentials and superior reversibility of modulated tungsten oxide hydrate photochromic thin films and nano inks with the assistance of LSPR and non-LSPR agents

Abstract

The photochromic materials that change their color with exposure to UV light are effective tools for the determination of radiation safety limits. The photochromic behavior depends on the electronic band structure and the charge transfer processes. These factors can be influenced by the physical and chemical properties of photochromic materials. Inspired by this, current work demonstrates the introduction of plasmonic (Cu & Al) and non-plasmonic (Zn & Sm) ions to modulate tungsten oxide hydrated (WO3.0.33H2O) nanostructures to intensify their energy-saving potential and reversible photochromic ability. To elaborate their practical applications, the thin films and the nano inks of the WO3.0.33H2O hybrid nanostructures were successfully prepared. The results demonstrated that the Cu ions assisted WO3.0.33H2O thin films changed their color completely in 30 s and printed nano inks took just 5 s to change their color while self-bleaching occurred in 3 and 1 h, respectively. The increased optical density and photochromic performance of the WO3.0.33H2O nanostructures with introduced ions are as follows: plasmonic (Cu & Al) > non-plasmonic (Zn & Sm) > pure WO3.0.33H2O. The improvement of WO3.0.33H2O nanostructures was credited with formed microstrains, active sites, transformed morphology, and different surface area by loaded plasmonic ions which offered high optical modulation through quick electron transfer by increasing their light absorption capacity. Aside from this, strong interactions between the W and plasmonic ions made it easier for protons to be inserted or extracted from the WO3.0.33H2O nanostructure which was helpful in higher photosensitivity. Overall, these hybrid nanostructures claim their potential candidature to be employed for smart windows, UV-sensitive switches, rewritable memory devices, etc.