Tunable thermochromism in V2O5films deposited by cathodic vacuum arc method by tailoring the oxygen deficiency

Abstract

Theromochromism and electrochromic coatings have promising applications in smart windows, IR sensors, and bio-medical devices. In this paper, we report the growth of vanadium oxide films using cathodic vacuum arc method for thermochromic application. Successive annealing of the as grown film shows the formation of yellow color V2O5 films. The color of the as grown films suggest the growth of highly disordered black VxOy film which after annealing gets converted into yellow V2O5 as confirmed by the X-ray diffraction and Raman spectroscopy. The scanning electron microscopy equipped with energy dispersive X-ray analysis was used to investigate the morphology and chemical composition of V2O5 phase. Although, the films gets completely converted into the stable phase after annealing but heating cycling of temperature significantly changes the color of the films in a reversible manner that confirms the thermochromic behavior. We propose a breathing of oxygen (tailoring of Oxygen within the films) responsible for such reversible change in the color. These studies open new pathways for investigating these films to electrochromic properties by locally heating the materials through electric current (through Joule heating) and change the optical properties.