Enhanced spectra selectivity of solar absorber film with Ti/Si3N4 photonic structures

A composite film of Al/Si3N4/(Ti/Si3N4)2, where 2 refers to two periods of Ti/Si3N4 photonic structures, for spectrally selective solar absorber was proposed theoretically and experimentally. The experimental thicknesses of the sub-layers Al, Si3N4 and Ti are approximately 80.9 nm, 26.8 nm and 67.4 nm, respectively. The film exhibits enhanced spectrum selectivity in accordance with the fraction of solar energy, i.e., high absorptance in the visible and near infrared regions, whereas high reflectance in the mid-far infrared regions. The experiments indicate that the average absorptance and reflectance values within their respective regions can simultaneously reach around 90%. This study offers a significant pathway to 1DPC applications for spectrally selective absorber film.