Facile Preparation of Zn2V2O7-VO2 Composite Films with Enhanced Thermochromic Properties for Smart Windows

Usually, VO2 films prepared by a magnetron sputtering method exhibit good durability and excellent solar modulation efficiency (Delta T-sol). However, its undesirable low-temperature luminous transmittance (T-lum) 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 degrees C, in which transparent Zn2V2O7 aimed to improve the optical performance. The composite film showed an enhanced thermochromic performance with a Delta T-sol of 11.5%, a T-lum of 49.0%, and a phase transition temperature (T-c) of 43.8 degrees C compared with a pure VO2 film (T-lum = 34.1%, Delta T-sol = 10.9%, T-c = 49.2 degrees 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.

Automated summary

In this research, a Zn2V2O7-VO2 composite film was deposited on quartz glass to improve the optical performance, showing enhanced thermochromic performance compared to a pure VO2 film. The composite film exhibited higher T-lum and Delta T-sol due to the formation and uniform distribution of Zn2V2O7, which widened the optical band gap and improved the optical properties.