Metamaterial Hybrid Smart Window Based on Nanoporous VO₂ Microparticles in Liquid Crystal for Heat Blocking and Visibility Control

With the growing concerns over energy consumption and climate change, the development of smart windows has become an area of intense research. In this paper, we report on the fabrication and testing of a hybrid smart window based on vanadium dioxide (VO₂) nanoporous microparticles (NMPs) embedded in a liquid crystal (LC). The metamaterial composite is scattering normally due to the formation of domains near each particle with a different refractive index than that of the surrounding LC molecules and becomes transparent as voltage is applied. Since the VO₂ particles are on the microscale, their absorption in the infrared is high partially due to the multiple reflections and scattering events. As a result, they block almost completely the infrared part of the solar spectrum, while enough visible light is transmitted. The applied voltage then controls the visibility, thus forming a hybrid window in which the heat is blocked, and the visibility is controlled with voltage. To evaluate it as a smart window, we prepared three devices, one with VO₂ NMPs, one with porous Si NMPs, and one with only LC showing that the first blocks more heat from entering the house than the second and the third. This VO₂-NMP/LC smart window device has potential applications in energy-efficient buildings and other related fields.