Ultra-broadband UV–VIS–NIR Absorbers Via Nanostructured Refractory Nitrides

The sun provides a widely available and clean source of energy that can support the world in addressing its energy demands with the help of powerful, ultra-broadband ideal solar absorbers. In the quest for the realization of perfect absorption in the visible range for applications in solar energy harvesting, we investigated the absorption effects of refractory nitride materials using numerical simulations. We studied three different materials (NbN, HfN, and TaN) with a circular nanoring structure for their highly efficient absorption of visible light. The meta-absorbers comprise subwavelength periodic patches whose top layer is made of refractory nitrides with a thin dielectric spacer over a highly reflecting thick layer of the same nitride material. All of them behaved as broadband absorbers in the visible region with absorptivity greater than 95