Wide-angle solar absorber using only titanium nitride for efficient solar photothermal utilization

Solar absorbers efficiently convert solar radiation into thermal energy through photothermal conversion, and are widely used in seawater desalination, energy storage. Titanium nitride (TiN) possesses outstanding absorption and thermal conductivity, but its narrow-band absorption restricts its performance. Periodic micro-nano architectures can strengthen multi-resonance coupling, boosting solar energy harvesting efficiency. Here, we proposed and analyzed a wide-angle and polarization-insensitive TiN solar absorber. It is made only of TiN material, consisting of nanoring and nanocolumn. The finite element method shows that the average absorption at 300-2500 nm plane wave is 88.7%, and the absorption of the AM1.5 solar spectrum is 95.2%. The high absorption is due to the coupling of surface plasmon resonance, cavity resonance and guided mode resonance, which greatly enhances the local electric field. Additionally, the influence of geometric parameters on its properties was clarified, and the manufacturing method was pointed out. Analysis of the incident and polarization angles proved its wide-angle and polarization-insensitive characteristics. This investigation highlights the potential of TiN for enhancing the efficiency of solar photothermal conversion absorbers.