Spectrally selective solar absorber and thermal infrared suppression based on hollow cylindrical microstructures

Abstract

In recent decades, the world's environmental troubles have become increasingly serious. Seeking new and environmentally friendly energy sources to replace chemical fuels is the key to improving environmental problems. As a renewable energy source, solar energy is the most promising and viable alternative energy source. In this paper, we present a spectrally selective solar broadband absorber with a hollow cylindrical microstructure. The model uses Ti film-Al2O3 film-Cu film as the substrate and Ti–Al2O3–Ti–Al2O3 (in the order from top to bottom) materials stacked to form hollow cylinders as the microstructure. The model was simulated using the FDTD Solutions software from Lumerical Solutions. From the simulation results, it can be seen that the absorption rates of the model in the solar radiation band 280 nm–4000 nm are all above 90%, and the average absorption rate is 94.1%; under the light of AM 1.5, the weighted average absorption rate is 94.8%. In addition, the reflectivity of the model in the 6516 nm–20000 nm band is all higher than 80%, with an average reflectivity of 94.2%, and the average reflectivity in the non-solar radiation band of 4000 nm–20000 nm is 85.4%, which has good thermal infrared suppression ability. In addition, we discovered the physical mechanism of model broadband absorption by analyzing the electric field distribution maps at different wavelengths. At the same time, the model has polarization insensitivity and wide-angle absorption properties. The excellent spectral selectivity allows this solar broadband absorber to operate in high temperature environments, which is very meaningful for the research of both solar thermophotovoltaic technology and thermal insulation and cooling materials.