A novel perspective on the design of thermochromic VO2 films: Combining ab initio calculations with FDTD simulations

Abstract Vanadium dioxide (VO2) has attracted a great interest in energy saving and smart coating applications because of its promising thermochromic properties. Generally, high luminous transmittance (Tlum) and good modulation capability of solar energy (ΔTsol) are desired. However, most experiments report that they have an antagonism relationship, meaning that it is difficult to improve both simultaneously and the point turns to find a balance between them. In this work, we put forward a novel perspective on the design of VO2 films. Ab initio calculations are associated with experimental results by finite-difference time-domain (FDTD) method. The refractive indexes of the rutile-like metal phase (R-VO2) and the monoclinic insulator phase (M-VO2) provided by ab initio calculations are imported into the FDTD simulations, where a series of configurations with various thickness are constructed. The simulation transmittance spectra of VO2 films are well consistent with our experiment results, of which the VO2 films are fabricated by High Power Impulse Magnetron Sputtering (HiPIMS). The present results provide an efficient and reliable approach to the improvement of smart material behavior.