Photoluminescence Characteristics for Hybrid Nanotubes of Light Emitting Poly(3-methylthiophene) Coated with Copper: Fluorescence Effect

The enhanced nanometer-scale photoluminescence (PL) and quantum yield of hybrid double layered nanotubes (HDLNTs) consisting of a light-emitting poly(3-methylthiophene) (P3MT) nanotube coated with nanometer-scale copper (Cu) metal were observed and presented. The HDLNTs of the Cu coated P3MT (P3MT/Cu) were synthesized through a sequential electrochemical synthetic method in an anodic alumina oxide (Al2O3) nanoporous template. We confirmed that the Cu nanotubes were covered outside the light emitting P3MT nanotubes based a high resolution transmission electron microscope image. From laser confocal microscope (LCM) PL experiments of an isolated single strand of the P3MT nanotubes and of their HDLNTs, we observed a similar to 100 times enhancement of the PL peak intensity for the HDLNTs of P3MT/Cu compared to that of the P3MT single nanotube, which was qualitatively confirmed through the measurement of the quantum yield. The energy and/or charge transfer effects in surface plasmon resonance contributed to the larger enhancement of the PL efficiency of the hybrid P3MT/Cu nanotubes. The PL decay life-time of the excitons of the P3MT nanotubes using a time resolved PL was not changed after the formation of the HDLNTs, implying that the PL enhancement of the hybrid nanotubes might have originated from fluorescence, not phosphorescence.