Novel laser texturing of W-doped VO2 thin film for the improvement of luminous transmittance in smart windows application

Abstract

Vanadium dioxide is a promising material for application in smart windows, which undergoes a metal-to-insulator transition, MIT, at 68 °C accompanied by a structural phase transformation, SPT, from VO2(M1) to VO2(R). In this study, two VO2 thin films, one W6+-doped and another one undoped, have been prepared. Both were synthesized via polymer-assisted sol–gel route. The effect of doping on thermochromic parameters was evaluated, giving rise to a reduction of the phase transition temperature by 21 °C with an IR modulation capability of 20 % in the doped sample. Additionally, doping effect on the thermochromic parameters and nanomechanical properties has been analyzed by Spectrophotometry and Atomic Force Microscopy. With the aim of recovering the luminous transmittance that decreased because of doping, the sample has been subjected to an innovative laser texturing process. This laser treatment is able to increase the luminous transmittance by almost 40 % without negatively affecting the other thermochromic parameters. Results show that the combination of both strategies, doping and laser texturing, leads to the production of VO2 thin films with low critical temperature, high solar and IR modulation capacity and enhanced luminous transmittance, with values close to those required for their real application in smart windows.