Biologically inspired flexible photonic films for efficient passive radiative cooling

Significance Some biological creatures have astonishing photonic structures to exhibit a thermal regulation ability. Taking inspiration from the brilliantly golden longicorn beetles, we demonstrate a bioinspired design of flexible hybrid photonic films for achieving efficient passive radiative cooling. Resonant polar dielectric microsphere particles were introduced into polydimethylsiloxane with photonic architectures to enhance the visible to near-infrared reflectivity and the midinfrared emissivity, enabling considerable subambient temperature drops under direct sunlight. This work paves the way toward radiative cooling technology based on photonic radiators with high performance and large-scale production, showing great potential for energy savings and efficient power generation.