Efficient, Scalable, and High‐Temperature Selective Solar Absorbers Based on Hybrid‐Strategy Plasmonic Metamaterials (Solar RRL 8∕2018)

Abstract

Solar‐thermal energy conversion is a promising technology that enables efficient harvesting of sunlight for a broad range of applications. High‐performance spectrally selective absorbers with excellent thermal stability are the key to developing efficient high‐temperature solar‐thermal systems. Recently, plasmonic metamaterial absorbers (PMAs) made of high‐loss and refractory materials have aroused special interests, because of their unique capability to trap and absorb sunlight through deep‐subwavelength structures with highly tunable spectral selectivity. However, the performance of current PMAs is far from satisfactory owing to both imperfect visible light absorption and ultrahigh infrared emission. Herein, by introducing out‐of‐plane plasmonic coupling between triangular nanodisks and a tantalum reflector in a metal–insulator–metal (MIM) sandwich structure, we developed 240‐nm‐thick hybrid‐strategy (structure‐, material‐, and shape‐based) PMAs, which demonstrate full‐spectrum sunlight absorption and greatly reduced infrared emission, ultimately boosting the record‐high solar‐thermal efficiency (1000 K) of PMAs from 66.4% to 77.3% under 100‐sun illumination. This superior performance is not only stable at temperatures of 1000 K, but also robust to the variations in the constituent materials of top nanodisks and dielectric spacers. Moreover, the performance of such PMAs is independent of the lateral periodicity or orientations of meta‐atoms, paving the way for their large‐scale deployment.