High performance multi-scaled nanostructured spectrally selective coating for concentrating solar power

Spectrally selective coatings (SSCs) are a critical component that enables high-temperature and high-efficiency operation of concentrating solar power (CSP) systems. In this Letter, we describe a novel design for a high-performance SSC based on multi-scaled nanostructures. Optimal design of the new structure for high optical performance of the SSC is predicted by the effective medium theory. To demonstrate the feasibility of the design, we fabricate the SSCs using fractal nanostructures with characteristic sizes ranging from similar to 10 nm to similar to 10 mu m. Optical measurements on these structures show unprecedentedly high performance with similar to 90-95% solar absorptivity and <30% infrared emissivity near the peak of 500 degrees C black body radiation. The newly developed concept of SSC could be utilized to design solar absorbers with high thermal efficiency for future high temperature CSP systems. Published by Elsevier Ltd.