A near-perfect metasurface solar absorber that integrates TiN square pillars and Ni cross nanostructures

The solar absorber is an important part of a green energy device that converts solar electromagnetic waves into heat energy. Solar Absorbers based on the material system of titanium compounds have received extensive attention. However, the most proposed absorbers still face a series of problems, such as the limited working wavelength range, the difficulty in further improving the absorption rate, and the extreme difficulty in actual manufacturing. In this paper, we propose a new metasurface solar absorber configuration that integrates titanium nitride (TiN) square pillars with nickel (Ni) cross nanostructures, building upon the established material system of titanium compounds. The absorber features a top layer of TiN square pillars and Ni nanocrosses, a middle layer comprising a TiN thin film and an aluminum oxide (Al 2 O 3 ) dielectric layer, and a bottom layer of TiN substrate, which can be fabricated by the standard electron beam overlay lithography process. The metasurface absorber based on our proposed configuration can achieve an average spectral absorption of over 98% and a total solar radiation absorption of 98.64% at ultra-wide wavelengths of 300–2500 nm. The excellent absorption performance of the absorber is comprehensively analyzed by the simulated field distributions. Furthermore, the analysis of changes in geometric parameters indicates that the proposed configuration possesses a moderate and acceptable fabrication tolerance. Moreover, the proposed absorber is highly insensitive to the polarization direction and the angle of incident light. This work can offer a practical and feasible path for designing and fabricating ultrahigh-performance solar absorbers.