Optical excitations of hybrid metal-semiconductor nanoparticles

We theoretically investigate Coulomb coupling effects in hybrid metal-semiconductor nanostructures, whose optical response is governed by plasmonic and excitonic effects (plexcitons). The plasmonic response of the nanoparticle is modeled within the framework of Maxwell’s equations, using a suitable dielectric function for the metal, and the excitonic response is described through the Schrödinger equation and the semiconductor Bloch equations. Our approach accounts for the quantum confinement of carriers in the semiconductor, for static screening in the formation of the exciton, and for a dynamic coupling between plasmons and excitons in the optical absorption or scattering. We apply our model to a prototypical CdS-based matchstick structure and investigate the importance of the various Coulomb coupling effects.