Ultra-broadband high solar absorption in checkerboard-shaped titanium nitride plasmonic metastructures

Abstract

Titanium nitride (TiN) has been proved as an efficient, refractory plasmonic material in solar energy harvesting applications. In this paper, we demonstrate the design of a simple metastructure, including a checkerboard-shaped TiN grating layer embedded in a SiO2 dielectric layer and a TiN film as a reflective layer, to realize highly efficient light absorption for solar energy harvesting. After systematically optimizing the geometric parameters of the metastructure by finite-difference time-domain (FDTD) simulations, we achieve high absorption rates with an average value up to 97% across an ultra-broad spectral range from 0.4 to 2.0 μm, significantly extending the light absorption ranges reported in prior work. Detailed analyses of the electric field elucidate that the unique checkerboard-shaped pattern results in plasmon hybridization between the adjacent TiN nano-ribbons at different resonant wavelengths. Combined with the high absorption due to the dielectric-like nature of TiN and Fabry-Perot resonances, the proposed metadevice achieves excellent light absorption performance within the solar spectrum, exhibiting great potential for various solar energy harvesting applications.