Theoretical calculation of the optical absorption property of nanoparticles composed of an Au Core and Si shell embedded in silica

Combining multiple materials in a single nanoparticle has gained much attention in recent years. In this work, the optical absorption property of gold-silicon (Au@Si) core-shell nanoparticles (NPs) embedded in a silica matrix were are theoretically demonstrated in the wavelength range from 400 to 800 nm, based on a discrete-dipole approximation method. For a single core-shell nanoparticle, the study revealed the localized surface plasmon resonance (LSPR) showed a regular redshift with an increase in its Si shell thickness. The observed redshifts in the LSPR peaks were in agreement with the experimental results. The optical absorption property was also observed for two Au@Si core-shell NPs separated, on average, by a distance as small as a few nanometers. The results suggest that the shifts in spectral peak position depend on both the interparticle distance and geometric configuration of the nanoparticles. The obtained results also suggest that this nanomaterial, with a strong wavelength-tuneable absorption property, could be an attractive candidate for applications in biomedicine, nanocatalysis, optical devices, and future functional devices.