Significantly enhanced photoluminescence of doped polymer-metal hybrid nanotubes

We report on the significantly enhanced photoluminescence (PL) of hybrid double-layered nanotubes (HDLNTs) consisting of poly(3-methylthiophene) (P3MT) nanotubes with various doping levels enveloped by an inorganic, nickel (Ni) metal nanotube. From laser confocal microsocopy PL experiments on a single strand of the doped-P3MT nanotubes and of their HDLNTs, the PL peak intensity of the KDLNT systems increased remarkably up to 350 times as the doping level of the P3MT nanotubes of the HDLNTs increased, which was confirmed by measurements of the quantum yield. In a comparison of the normalized ultravoilet and visible absorption spectra of the doped-P3MT nanotubes and their HDLNTs, new absorption peaks corresponding to surface-plesmon (SP) energy were created at 563 and 615 nm after the nanoscale Ni metal coating onto the P3MT nanotubes, and their intensity increased on increasing the doping level of the P3MT nanotabe. The doping-induced bipolaron peaks of the HDLNTs of doped-P3MT/Ni were relatively reduced, compared with those of the doped-P3MT nanotubes before the Ni coating, due to the charge-transfer effect in the SP-resonance (SPR) coupling. Both energy-transfer and charge-transfer effects due to SP resonance contributed to the very-large enhancement of the PL efficiency of the doped-P3MT-based HDLNTs.