A highly efficient ultra-broadband and wide-angle plasmon absorber based on nanocavity arrays for solar harvesting

As the demand for renewable energy continues to rise, developing efficient solar energy harvesting technologies has become increasingly important. In this paper, we propose a plasmon absorber utilizing nanocavity arrays to achieve ultra-broadband absorption of solar energy. The results show that the absorber achieves an average absorption rate of 95.34% and an AM1.5 weighted absorption efficiency of 97.7% within 500–2500 nm. The broadband absorption originates from the combined effects of surface plasmon resonances (SPR), cavity-mode resonances, and interactions between different material layers. Moreover, the proposed structure demonstrates polarization insensitivity and wide-angle stability, maintaining high absorption rates even at large incidence angles, such as 95.7% at 85°. In addition to its superior absorption capabilities, the structure also demonstrates excellent thermal radiation performance, achieving a thermal radiation efficiency of 94.77% at 2000 K. These outstanding performances in broadband absorption, angular stability, and thermal radiation efficiency make it a promising candidate for applications in solar energy harvesting and photothermal conversion systems.