Multiscale Ultrabroadband Polymer Scattering Media with Tailored Emittance for Radiative Thermal Management

TL;DR

This paper presents a scalable, metal-free multilayered photonic medium that achieves high infrared emission and solar reflectance for passive radiative cooling, validated by field tests and theoretical models.

Contribution

It introduces a novel multiscale scattering architecture for selective LWIR emission and solar reflection, advancing radiative thermal management without metallic reflectors.

Findings

High LWIR emittance of 0.88

Solar reflectance of 0.97

Enhanced cooling performance in field tests

Abstract

A surface that selectively emits heat in the long-wave infrared (LWIR) can enable passive cooling in hot environments while retaining partial radiative insulation in cold conditions, but its real-world deployment is limited by reliance on ultrabroadband metallic reflectors such as silver. Here we engineer random photonic media with a layered, multiscale scattering architecture to simultaneously achieve ultraviolet-to-far-infrared reflection and selective LWIR emission. We validate our approach by developing a metal-free selective emitter that exhibits high LWIR emittance (0.88), strong solar reflectance (0.97), and low thermal emittance outside the LWIR (0.49), independent of the substrate. Field tests, supported by theoretical modeling, show enhanced radiative cooling and thermoregulation across diverse applications relative to conventional broadband emitters. Leveraging the low cost and scalable manufacturing of scattering media, this work provides a pathway to advance radiative thermal management, enabling energy saving and improved thermal comfort.