Angle‐Independent and Polarization‐Insensitive Colored Daytime Radiative Cooler Design Based on Ultra‐Broadband Metasurface Thermal Emitter

ABSTRACT

We numerically demonstrate a broadband long‐wave infrared (LWIR) absorber with near‐zero visible–near‐infrared (Vis–NIR) absorption, enabling daytime radiative cooling with colored display. The structure comprises two patterned black phosphorus (BP) resonator layers separated by a dielectric spacer and backed by an optically thick metallic reflector. Although BP inherently exhibits strong in‐plane optical anisotropy, polarization‐ and angle‐insensitive behavior is achieved through the fourfold rotational symmetry of the metasurface unit cell. Full‐wave electromagnetic simulations show an average absorptance exceeding 98% across the LWIR (8–14 ) for both transverse electric (TE) and transverse magnetic (TM) polarizations, with stable performance for incident angles up to , while absorptance in the VIS–NIR range (0.4–2.5 ) remains below 5.5%. Under realistic daytime conditions, the resulting spectral emissivity yields a maximum net cooling power of approximately 94 W  and a steady‐state temperature reduction of about 7.8 below ambient. Colorimetric analysis based on the CIE 1931 standard illuminant D65 confirms a warm‐yellow reflected appearance, demonstrating stable color display alongside efficient radiative cooling. The proposed BP‐based dual‐layer metasurface thus offers a compact, polarization‐ and angle‐insensitive, spectrally selective platform for infrared thermal management, daytime radiative cooling, and multifunctional photonic applications.