Metasurface-Based Selective Emitter for Passive Radiative Cooling

Abstract

Most of the cooling currently rely on air conditioning system, which requires a large amount of energy for cooling. Accordingly, passive radiative cooler is currently the leading replacement for air conditioner. Selectively, and strongly emitting heat toward the cold outer space using the atmospheric window where the peak of the black body at ~300 K matched coincidentally, the cooler cools below the ambient air temperature without any electricity. However designing selective emitter is always challenging owing to material limit, restraining cooling performance. Here, we suggest near-perfect selective emitter which has ~0.9 emissivity over the main atmospheric wavelength region(8 to 13 μm) by overcoming the phonon-polariton resonance. Using plasmonic metasurface of structured quartz substrate coated with silver and polydiethylsiloxane(PDMS), inevitable emission dip is crammed up at specific mid-infrared region of atmosphere. This result provide one potential way of tailoring emission spectrum for passive radiative cooling.