Highly efficient flexible structured metasurface by roll-to-roll printing for diurnal radiative cooling

An ideal radiative cooler requires accurate spectral control capability to achieve efficient thermal emission in the atmospheric transparency window (8-13 mu m), low solar absorption, good stability, scalability, and a simple structure for effective diurnal radiative cooling. Flexible cooling films made from polymer relying on polymer intrinsic absorbance represent a cost-effective solution but lack accuracy in spectral control. Here, we propose and demonstrate a metasurface concept enabled by periodically arranged three-dimensional (3D) trench-like structures in a thin layer of polymer for high-performance radiative cooling. The structured polymer metasurface radiative cooler is manufactured by a roll-to-roll printing method. It exhibits superior spectral breadth and selectivity, which offers outstanding omnidirectional absorption/emission (96.1%) in the atmospheric transparency window, low solar absorption (4.8%), and high stability. Impressive cooling power of 129.8 W m-2 and temperature deduction of 7 degrees C on a clear sky midday have been achieved, promising broad practical applications in energy saving and passive heat dispersion fields.

Automated summary

This study proposes and demonstrates a metasurface radiative cooler based on periodically arranged three-dimensional trench-like structures in a thin polymer layer, which exhibits excellent spectral control capability and efficient cooling performance. The cooler offers outstanding omnidirectional absorption/emission in the atmospheric transparency window, low solar absorption, and high stability, promising broad applications in energy saving and passive heat dispersion fields.