Realization of efficient radiative cooling in thermal emitter with inorganic metamaterials

Abstract In this work, we have proposed a thermal emitter composing of triangular prism metamaterials deposited on a multilayer film. Ultra-high average emissivity and broadband spectra have been realized in the first and second atmospheric windows, where the patterned metamaterial is responsible for the high transmission and the multilayer serves as a reflector in the solar band. The corresponding electric field distribution at resonant positions are explored elaborately to figure out the origin of such high emissivity. Moreover, controllable emissivity is achieved with different incident angles for both the transverse electric and transverse magnetic polarization. In particular, the net cooling power approaches a high value with considering the radiative cooling performance in the daytime and night-time separately. Finally, the influence of the geometry parameters is also demonstrated to obtain optimal high emissivity. Our proposed inorganic metamaterials design paves a new avenue in the application of thermal emitter and thermal management.