Ultra-wideband solar perfect absorber for photothermal conversion with high manufacturing error tolerance

Solar energy is a key way to solve today's energy and environmental crises, and the full collection and utilization of solar energy requires a solar absorber with a broader spectrum and higher efficiency. Here, we present a solar metamaterial absorber, consisting of a Ti substrate, a Si3N4 dielectric spacer layer, and a Ti–SiO2 patterned layer. The results of the simulation show that the average absorption of the absorber is 98.16% in the range of 200–4200 nm under normal incidence. Its high absorption is attributed to the interaction of magnetic resonance (MR), cavity resonance (CR), guided mode resonance (GMR) and surface plasmon resonance (SPR). Moreover, the total absorption of the absorber in the AM1.5 standard solar radiation spectrum is 97.8% and the total absorption of blackbody radiation at 1500 K is 98.0%. In addition, the total photothermal conversion efficiency is still 92.2% at 1000 K. The proposed metamaterial absorber is also characterized by wide-angle incidence insensitivity, polarization-independence and a high tolerance of fabrication errors, which can be practically applied in the field of solar energy harvesting.