TiN-Ti ultra-broadband solar absorber: Efficient heat absorption and high thermal stability

This paper presents an innovative TiN-Ti ultra-broadband solar absorber with a tic-tac-toe window design, showcasing exceptional performance for solar energy applications. The absorber features a Ti-TiN-Ti layered structure, with the top TiN-Ti layer crafted into a tic-tac-toe pattern and a central square pillar. Finite-difference time-domain (FDTD) simulations demonstrate a remarkable average absorption rate of 95.52 % across the 250–3500 nm range, with a 3070 nm effective bandwidth and a 95.97 % absorption rate under AM1.5 conditions. High absorption stems from the synergistic coupling of SPR, guided mode resonance and cavity resonance, as revealed by electromagnetic field analysis. The absorber excels in polarization insensitivity and angular robustness, The high absorption rate of the absorber remains consistent within the incident angle range of 0°-30° However, when an electromagnetic wave with an inclination of 60° is incident upon the absorber, the absorption bandwidth, which exhibits an absorption rate close to 1, remains at 2000 nm. With superior performance compared to existing designs and thermal radiation efficiency exceeding 90 % from 300 K to 2000 K, this absorber offers significant potential for solar energy harvesting, thermophotovoltaics, and communication systems.