Remarkable improved solar transmission of VO2 smart windows by partial controlled oxygen plasma bombarding

The vanadium dioxide (VO2) based smart windows are developed to reduce energy consumption and improve thermal and visual comfort by controlling the solar flux entering into a building. In this paper, the solo oxygen plasma bombarding is adopted at low temperature (30 degrees C) for the solar transmission improvement in VO2 smart windows, which helps to overcome the constraints of destruction in toughened VO2 windows by annealing. Various oxygen flow rates were used to assist the plasma to identify the influence and mechanism in thermochromic VO2 films for the first time. The oxygen plasma treatment leads to an effective composition modulation and microstructure reconstruction in the VO2 films to create new functionalities. The conversion between VO2 and V2O5 can be controlled and maintained stable during the O-2 flow range of 120-160 sccm (called stable zone). Favorable results are achieved in the stable zone compared with the untreated VO2 films, the relative improvement of luminous transmission T-lum (380-780 nm) is 44%, meanwhile, the increase of T-sol (380-2500 nm) is 30% with a negligible decrease of 1.5% in Delta T-sol. Additionally, the solar transmission of VO2 films can be emphatically improved with preserved phase transition behaviors. It reveals that the proposed technique is simple, efficient and performed with ease in working tolerance, and can be applied widely in the VO2 smart window field. (C) 2019 Elsevier B.V. All rights reserved.