Near-Wavelength Sculpturing-Evoked Radiative Cooling

Radiative cooling, inspired by the silver ants of the Sahara Desert, is gaining increasing interest for its cost-effectiveness and zero energy consumption. However, it remains imperative and challenging to deal with high-temperature environments, which are inevitably required in many cutting-edge applications. We proposed the direct femtosecond laser sculpturing of near-wavelength microgrooves on substrates to evoke powerful radiative cooling. Sharp edges of the microgrooves, with features on several micrometers, induced intense surface plasmon resonance (SPR) absorption, which can be precisely tuned by adjusting the groove depth and width. The SPR effectively enhanced mid-infrared emittance through the atmospheric transparency window, enabling a temperature drop of up to 24 °C at a measuring temperature of ∼419 °C. Without additive layers, the method achieved favorable lightweighting while maintaining functional stability at above 400 °C temperatures. We expect that the technology will unlock access to expanded opportunities in many pioneering applications.