Facile Preparation of Zn<sub>2</sub>V<sub>2</sub>O<sub>7</sub>–VO<sub>2</sub> Composite Films with Enhanced Thermochromic Properties for Smart Windows
Yongqiang Zhang, Bin Li, Zhe Wang, Shouqin Tian, Baoshun Liu, Xiujian Zhao, Neng Li, Gopinathan Sankar, Shifeng Wang
Abstract
Usually, VO2 films prepared by a magnetron sputtering method exhibit good durability and excellent solar modulation efficiency (ΔTsol). However, its undesirable low-temperature luminous transmittance (Tlum) limits its application in smart windows since the dense film composed of VO2 nanocrystals with narrow band gaps can absorb more visible light. In this work, a Zn2V2O7–VO2 composite film was deposited on quartz glass by a facile magnetron sputtering method followed by postannealing at 450 °C, in which transparent Zn2V2O7 aimed to improve the optical performance. The composite film showed an enhanced thermochromic performance with a ΔTsol of 11.5%, a Tlum of 49.0%, and a phase transition temperature (Tc) of 43.8 °C compared with a pure VO2 film (Tlum = 34.1%, ΔTsol = 10.9%, Tc = 49.2 °C). This was probably attributed to the formation and uniform distribution of Zn2V2O7 in the composite film, which could widen the optical band gap, leading to the improvement in the optical properties. The interface between Zn2V2O7 and VO2 could produce interfacial stress to reduce the phase transition temperature. Therefore, this work can provide a facile way to improve the thermochromic performance of VO2-based films and promote their application in the field of energy-saving glass.