Two-Dimensional SiO₂/VO₂ Photonic Crystals with Statically Visible and Dynamically Infrared Modulated for Smart Window Deployment

Two-dimensional (2D) photonic structures, widely used for generating photonic band gaps (PBG) in a variety of materials, are for the first time integrated with the temperature-dependent phase change of vanadium dioxide (VO₂). VO₂ possesses thermochromic properties, whose potential remains unrealized due to an undesirable yellow-brown color. Here, a SiO₂/VO₂ core/shell 2D photonic crystal is demonstrated to exhibit static visible light tunability and dynamic near-infrared (NIR) modulation. Three-dimensional (3D) finite difference time domain (FDTD) simulations predict that the transmittance can be tuned across the visible spectrum, while maintaining good solar regulation efficiency (ΔT_sol = 11.0%) and high solar transmittance (T_lum = 49.6%). Experiments show that the color changes of VO₂ films are accompanied by NIR modulation. This work presents a novel way to manipulate VO₂ photonic structures to modulate light transmission as a function of wavelength at different temperatures.