Ultra-broadband solar energy absorber based on Ti and TiN from visible to mid-infrared

Abstract In this work, a metamaterial absorber based on titanium (Ti) and titanium nitride (TiN) is proposed. Theoretical calculation by finite-difference time-domain (FDTD) method shows that the absorber could achieve a bandwidth of 3720 nm in the spectrum range of 280 nm − 4000 nm. The average absorptivity of the absorber can reach 96.9%. The physical mechanism of the absorber is analyzed from the impedance matching theory and electromagnetic field distribution. Furthermore, simulation results illustrate that the absorber is polarization-insensitive and allows a wide range of incident angles. The absorption spectrum is basically consistent with that of air mass 1.5 (AM1.5). And it can achieve high thermal conversion efficiencies over a wide range of temperatures. These results indicate that the absorber has a good development prospect in solar energy collection.