A spectroscopic study on the interaction between upconversion nanoparticles and plasmonic nanostructure

In order to overcome the low quantum yield of upconversion nanoparticles (UCNPs), plasmonic nanostructures have been used due to their strongly modified local E-field. However, the complex nature of plasmon-upconversion interaction by field enhancement and luminescence quenching is not well appreciated in general. Here, we present a spectroscopic study on the interaction between NaYF4:Yb3+,Er3+ UCNPs and gold nanostructures. The luminescence is monitored as the nanostructure geometry is varied. The interplay between the positive effect of local field enhancement and the negative effect of luminescence quenching is carefully analyzed by numerical simulations and rate equation analysis.