Recent advances in VO2-based thermochromic composites for smart windows

Vanadium dioxide (VO2) is a well-known thermochromic material since it exhibits a notable optical variation in the near-infrared region from transmitting to reflecting upon the semiconductor-to-metal phase transition (SMT). This distinctive character makes it attractive in thermochromic smart window applications. However, the development of VO2 in energy-efficient windows is hindered by high transition temperature (T-c), low luminous transmittance (T-lum), small solar modulation efficiency (T-sol), the uncertainty of durability, and the lack of color change. To solve the above problems, researchers have made great efforts in VO2-based composites and found that using composite materials with different fabrication methods revealed the most satisfactory performance. This review focuses on the use of composite structures (core-shell nanostructure, hybridization, multilayer structure, etc.), and we discuss preparation methods, material structures, and prospects of VO2-based thermochromic composites for smart windows.