Nanoscale luminescence characteristics of CdSe/ZnS quantum dots hybridized with organic and metal nanowires: energy transfer effects

Abstract

Hybrid nanosystems comprising functionalized CdSe/ZnS core-shell quantum dots (QDs) on the surface of light-emitting poly(3-hexylthiophene) (P3HT), metallic copper (Cu), and insulating polystyrene (PS) nanowires (NWs) are fabricated. Using high-resolution scanning transmission electron microscopy, we observe that the QDs are attached to the surface of the NWs. The nanoscale photoluminescence (PL) characteristics of the hybrid QD/P3HT, QD/Cu, and QD/PS single NWs are investigated using laser confocal microscopy (LCM) with high spatial resolution. For the hybrid QD/P3HT single NW, the LCM PL intensity from the P3HT NW increases considerably, while that of the QDs decreases due to Forster resonance energy transfer. Hybridization affects the nanoscale PL characteristics of both the P3HT NW and the QDs. The LCM PL intensity of the hybrid QD/Cu NW is three times higher than that of the QD/PS NW, because of surface plasmon resonance coupling energy transfer between the QDs and the Cu NW. Time-resolved PL spectra reveal that the exciton lifetimes of the QDs drastically decrease after the hybridization with P3HT or Cu NWs, due to energy transfer effects. The nanoscale PL efficiency of the QDs can be controlled by hybridization with NWs having distinct properties.