Photoluminescence properties of silicon nanocrystals interacting with gold nanoparticles via exciton-plasmon coupling

The photoluminescence (PL) properties of silicon nanocrystals (Si NCs) deposited on gold nanostructures have been studied regarding PL intensity and lifetime. In contrast to most investigations, which attempt to optimize the overlap between the plasmon resonance and the Si NCs' PL band, we chose much smaller gold nanoparticles to achieve an improved exciton-plasmon coupling. PL enhancements of up to 20 were observed near the plasmon resonance. In the maximum of the PL band at 710 nm, we determined a PL enhancement of similar to 4 while the average PL lifetime was found to increase from 45 to 66 mu s. The experimental observations were successfully explained with a model invoking bidirectional energy transfer between excitonic and plasmonic states, being operative in addition to the normal exciton recombination rate enhancement.