Coupling and Energy Transfer between an Exciton in a Semiconductor Quantum Dot and a Surface Plasmon in a Metal Nanoparticle

The coupling between excitons in semiconductors or molecules and metal nanoparticles has been well-studied, primarily for nanoparticles in their ground electronic state. However, less attention has been given to exciton–nanoparticle interactions when the nanoparticle generates surface plasmons upon incident excitation. In this study, we explore the coupling and energy transfer dynamics between an exciton and the surface plasmon of a metal nanoparticle, forming a “plexciton”. Significant mutual energy exchange between the exciton and the plasmon leads to unexpected effects on the exciton lifetime and coupling strength. The interaction at varying wavelengths, orientations, magnitudes, and phases was studied. Our results show that the exciton decay rate can be quenched entirely when the plasmon’s energy compensates for that of the exciton radiative decay, even at separation distances of several hundred nanometers. These findings highlight the impact of surface plasmons on exciton dynamics, opening new possibilities for enhancing charge carrier dynamics in coupled systems.