Light Absorption and Scattering Spectra of Semiconductor/Metal/J-Aggregate Hybrid Nanoshells

Abstract

We report a study of optical properties of silver and gold nanoshells with a semiconductor core and an external organic layer of the molecular J-aggregate of the TDBC dye. Absorption and scattering cross sections of light are calculated using the generalized Mie theory for three values of the outer radius of the intermediate metal shell of the nanoparticle (10, 70, and 100 nm), with its thickness varying in the range from 0 to 20 nm. Qualitatively different behavior of the optical spectra of the studied nanostructures is demonstrated depending on their composition and geometric parameters. It is found that for the considered core materials (Si, GaP, and ZnSe) in the system in question, weak and strong plasmon–exciton coupling regimes can be implemented, including regimes exhibiting the induced transparency effect. It is shown that in the light scattering cross sections of three-layer ZnSe/Au/TDBC nanoparticles, the Fano antiresonance effect is observed, manifested in the asymmetric behavior of the spectral band contour. The above effects stem from the near-field electromagnetic coupling of dipole and multipole plasmons in the intermediate metal shell (Ag or Au) of the system with a semiconductor core and an outer organic excitonic shell. The results of the work contribute to a deeper understanding of the effects of near-field electromagnetic coupling in metal-containing organic–inorganic nanostructures. The studied nanoparticles are of interest for the development of new hybrid materials with specified optical properties and for the creation of a number of effective photonic devices on their basis, including highly sensitive sensors and photodetectors.