Luminescence variation of organic Alq3 nanoparticles on surface of Au nanoparticles and graphene

We demonstrate the variation of photoluminescence (PL) intensity for tris(8-hydroxyquinoline) aluminum(III) (Alq3) nanoparticles (NPs) depending on the use of a thin layer of gold (Au) NPs or a graphene substrate. The high luminescence Alq3 NPs were fabricated by a re-precipitation method. Laser confocal microscope (LCM) PL spectra were measured and used to analyze the nanoscale light-emission characteristics of the Alq3 NPs with glass, a layer of Au NPs or graphene as a substrate. PL enhancement of the Alq3 NPs attached to a layer of Au NPs was observed, while a considerable reduction of PL intensity for Alq3 NPs when a single layer of graphene was used for the substrate was observed. Color charge-coupled device and LCM PL mapping images directly confirmed the variation of PL intensities. We observed that the Raman spectra of Alq3 NPs also changed according to the substrate used. The PL enhancement of Alq3 NPs on a layer of Au NPs originated from surface plasmon resonance coupling. On a single layer of graphene substrate, the PL quenching of the Alq3 NPs occurred due to a resonance energy transfer effect.

► Fabrication of Alq3 nanoparticles (NPs) through re-precipitation method without surfactant.
► Enhancement of PL intensity for Alq3 NPs on thin layer of Au NPs is due to surface plasmon resonance coupling.
► PL reduction of Alq3 NPs on a graphene substrate originates from resonance energy transfer effect.