LAUSR

Abstract In order to enhance the thermal stability and thermochromic properties, three kinds of VO x -based thin films with different structures (single-layer, triple-layer and multi-layer, respectively) were designed in this study. All of them were prepared by room-temperature reactive magnetron sputtering and subsequently rapid thermal annealing (RTA) in nitrogen atmosphere. The optical properties and microstructure of VO x -based thin films were investigated. The results reveal that all samples are ascribed to pure VO 2 (M), and the VO x -based thin films exhibit superior thermochromic properties with the solar modulation (Δ T sol ) up to 12.75%, 15.65% and 18.02%, respectively. The phase transition temperature ( T c ) is as low as 54 °C for multi-layer thin films without doping, which indicates that the film design could effectively enhance optical switching and depress the T c . After thermal treatment in the air, the phase of V 2 O 5 appeared at 325 °C, 275 °C and 375 °C for single-layer, triple-layer and multi-layer thin films, respectively, which indicates the multi-layer thin films show the best thermal stability. According to the degradation mechanism in this paper, the unbalance of interfacial stress and oxygen vacancies in VO x thin film accelerated the oxidation process, which results in the disappearance of thermochromic properties. Furthermore, the multi-layer thin films still show superior Δ T sol of 16.56% and T c of 56 °C, when it was taken out at 400 °C and cooled quickly in air. Meanwhile, the annealing period could be reduced by 75% in comparison to cooling in vacuum chamber. Our research set forth a new avenue in enhancing the thermal stability and production efficiency, which can promote the practical applications of VO x -based thin films.