Enhance energy transfer between quantum dots by the surface plasmon of Ag island film

Abstract

We observed enhanced energy transfer between quantum dots which were spin coated on the surface of Ag island film. By adjusting the thickness of Al2O3 spacer layer (4-16 nm) between quantum dots and Ag island film, we studied the distance dependence of the plasmon enhanced energy transfer. Experimental results showed the energy transfer efficiency increased as the quantum dots approached closer to the Ag film. A time-correlated single-photon counting system was also applied to study the dynamics of the plasmon enhanced energy transfer between quantum dots. Obvious decay rate increasing was discovered from time-resolve photoluminescence spectra of both the donor and accepter quantum dots, which clearly confirmed the existence of strong photon-exciton interaction. The theoretical analysis performed by the finite difference time domain method and COMSOL program, further revealed large electronic field and energy transfer rate enchantments on the surface of Ag island film, which uncovered the dominant reasons for the quantum dots’ enhanced energy transfer.