Enhanced Biexciton Emission From Quantum Dots Near Plasmonic Nanostructures

Metal and semiconductor quantum dots (QDs) exhibit unique size and composition dependent optical properties. The key elements that determine their optical properties are localized surface plasmons in metal nanoparticles and excitons in quantum dots. When QDs are placed near Au@SiO2 core@shell nanoparticles, their exciton/multiexciton emission lifetimes and quantum yields are modified due to the exciton-plasmon interaction. At the single QD level, we found that the ratio between the biexciton and exciton quantum yields of the QDs near Au nanoparticles was increased, leading to a small photon antibunching “dip”. Electrodynamics modeling revealed that biexciton quantum yield of single QDs was increased while the exciton quantum yield decreased due to the plasmonic structures. In another study, we find the biexciton quantum yield of QDs near Au nanoparticles are dependent on the excitation wavelength. The emission of single QDs changes from photon antibunching to bunching by exciting the QDs close to the plasmon resonance. These studies suggest that plasmonic structures can be used to modify the exciton/multiexciton emission efficiency of QDs.