Temperature-Selective Emitter

To achieve control of radiative emissivity of a material, we propose and demonstrate a vanadium dioxide (VO2)-based temperature-selective emitter. This emitter comprises layered VO2 and thin W-doped VO2 with decreased metal-insulator transition temperature. Because a metal-insulator-metal structure is realized only in the temperature range 46-61 degrees C, the emissivity enhanced only in this temperature range. We analytically calculated the temperature-dependent emissivity spectra and experimentally measured the temperature-dependent reflectance spectra and emissivity. Direct heat flux measurements of the fabricated device showed emissivities of 0.19, 0.45, and 0.24 for temperatures of <30 degrees C, 46-61 degrees C, and >71 degrees C, respectively. The emitter presented in this study contributes to the realization of the active control of thermal emission in various situations.