Tunable thermochromism of VO2 on SiO2/Si in the visible region

Vanadium dioxide (VO2) undergoes an insulator-to-metal phase transition above room temperature, across which the optical transmittance changes dramatically in the infrared region. In contrast, the transmittance modulation in the visible region is limited. Thus, VO2 exhibits visible transparency in both the insulating and metallic phases. Here, we show that insulating VO2 supported on SiO2/Si substrates can be colored, with the color varying widely with VO2 thickness. The color of a VO2/SiO2/Si heterostructure was observed to change sharply across the thermal phase transition. The observed color modulation can be well reproduced by numerical calculations based on the multiple-reflection model, suggesting that the Fabry–Pérot interference effect contributes to the visible thermochromism. Our results would expand the possibility of thermochromic applications of VO2 in the visible region.