Ultra-broadband perfect absorber based on self-organizing multi-scale plasmonic nanostructures

Abstract Aside from well-performed light confinement, practical and scalable plasmonic perfect absorbers also depend on stable material scenario, as well as compact design and convenient fabrication. However, it still remains a challenge to make enclosed (no air exposure), multi-scale plasmonic nanostructure for constructing perfect absorbers. Herein, we report a direct self-organization growth of ultrathin (∼130 nm) multi-scale Ag nanostructures in SiO2 matrix on quartz or plastic substrates via sputtering. Based on the elaborate microstructure design, the cavity-mode excitation, local plasmon resonances and their lightning-rod effects are synergistically activated, yielding a near constant absorptance of over 95% across the 300–1700 nm wavelength even with some reflectance loss from the quartz surface and more than 98% visible absorptance with a simple antireflection treatment. Further, due to the enclosed nanostructures, the wide-angle absorbers present outstanding light-to-heat capability and thermal robustness under concentrated solar illumination. The simple material recipe (Ag, SiO2) and fabrication scheme suggest that our approach is with easy scalability. We anticipate that the proposed concept in this study can facilitate the rapid development of highly efficient ultrathin perfect absorbers.