Energy transfer effect of hybrid organic rubrene nanorod with CdSe/ZnS quantum dots: Application to optical waveguiding modulators

Organic rubrene (5,6,11,12-tetraphenyltetracene) nanorods (NRs) were fabricated through the physical vapor transport method for the study of active fluorescence optical waveguiding and its modulation. The functionalized CdSe/ZnS quantum dots (QDs) with blue and green emissions were partially attached to the surface of the rubrene NR. Using a high resolution laser confocal microscope (LCM), the nanoscale photoluminescence (PL) intensity of the pristine rubrene portion of the hybrid NR/QDs was observed to be considerably enhanced after it was attached with blue (or green) QDs. The nanoscale optical waveguiding characteristics of the hybrid NR/QDs were investigated in terms of the output LCM PL spectra as a function of propagation distance. We observed more efficient optical waveguiding characteristics from the hybrid rubrene NR/blue-QDs than from the pristine NR and the hybrid rubrene NR/green-QDs. These results can be analyzed in terms of the higher Fِrster resonance energy transfer efficiency for hybrid rubrene NR/blue-QDs system. The results and analysis were supported by a drastic decrease of exciton lifetime of QDs in the hybrid region as measured by time-resolved PL decay curves.