Extremely broadband ultralight thermally-emissive optical coatings

We report the design, fabrication and characterization of ultralight highly emissive structures with record mass per area that emit thermal radiation efficiently over a broad spectral (2 to 35 microns) and angular (0–60o) range. The structures comprise one to three pairs of alternating metallic and dielectric thin films, and have measured effective 300 K hemispherical emissivity of 0.7 to 0.9 (inferred from angular measurements). To our knowledge, these micron-scale-thickness structures, are the lightest reported optical coatings with comparable infrared emissivity. The superior optical properties, together with their mechanical flexibility, low outgassing, and low areal mass, suggest that these coatings are candidates for thermal management in applications demanding of ultralight flexible structures, including aerospace applications, ultralight photovoltaics, lightweight flexible electronics, and textiles for thermal insulation.