Investigation of a double-patterned TiN architecture for ultra-wideband solar absorption and thermal emission

With the growing global energy crisis, the development of efficient solar absorbers has become increasingly important. In this work, a broadband solar absorber based on a double-patterned TiN architecture is proposed and numerically investigated using the finite-difference time-domain (FDTD) method. The absorber consists of a Ti substrate, a TiN grating layer, a SiO₂ dielectric spacer, and a TiN microstructure array. Simulation results show that the proposed structure exhibits absorptivity above 90% over the wavelength range of 250-3110 nm, corresponding to an ultra-broad bandwidth of 2860 nm. The average absorptivity reaches 96.42%, and the AM1.5-weighted solar absorption efficiency is 95.7%, with an energy loss of only 4.3%. Electromagnetic field analysis indicates that the excellent broadband absorption originates from the synergistic effects of localized surface plasmon resonance, Fabry-Perot cavity resonance, and multimode coupling. In addition, the absorber maintains absorptivity above 90% for incident angles from 0° to 60°, demonstrating good angular stability and polarization insensitivity. Thermal radiation analysis further confirms its promising high-temperature performance. Owing to its excellent absorption capability, structural simplicity, and potential thermal robustness, the proposed absorber shows considerable potential for applications in solar-thermal energy harvesting, desalination, photovoltaics, and thermophotovoltaic systems.