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Solar absorber is the key component to realize efficient utilization of solar energy. In this paper, only titanium nitride (TiN) is used to create a broadband, wide-angle, polarization insensitivity solar absorber. The average absorption of the absorber in the spectral range of 300-2500 nm is 91.3%. The distributions of electric and magnetic fields indicate that the strong absorption is caused by the coupling effect of surface plasmon resonance and guided mode resonance. Investigate the effects of the geometric parameters of the absorber on the spectral absorption performance. Moreover, we also discuss the absorption performance of the solar absorber at different incidence angles. It is demonstrated that even at a large incidence angle of 60°, the average spectral absorption can exceed more than 70%. The proposed solar energy absorber is also insensitive to polarization. The research results in this work could benefit the applications in solar thermophotovoltaic system. [ABSTRACT FROM AUTHOR]

Novel nanofluids (NFs) based on bio-nanotechnology have enormous potential for solar thermal utilization. The biomimetic nanoparticles (NPs) nanostructures provide new ideas for the design of solar collector medium. Inspired by the biological properties of waxberry, we proposed waxberry-shaped biomimetic nanoparticles (WSBNPs) for solar thermal conversion in this work. Numerical results show TiN WSBNPs exhibit good optical absorption properties compared to Ag- and Au-based WSBNPs. When the volume fraction f v = 5 × 10−6 and the depth h = 15 mm, the photothermal conversion efficiency η abs can reach 93.9%. The mechanistic analysis shows that the high absorption performance of WSBNPs can be attributed to the presence of the "lightning rod" effect on the surface of NPs and the mutual coupling of surface plasmon resonance. The η abs of TiN WSBNPs can reach 90% at a lower penetration h = 11 mm and f v = 5 × 10−6. Meanwhile, the η abs of WSBNPs is proportional to the number of protrusions on the exterior surface. It has been shown that TiN WSBNPs with a raised exterior surface have excellent potential for efficient solar energy utilization. [ABSTRACT FROM AUTHOR]