Para-hexaphenylene (p-6P) nanofibers grown on a silver surface for polarization-insensitive surface plasmon polariton excitation

Surface plasmon polariton excitation was demonstrated by fluorescent light from organic para-hexaphenylene (p-6P) nanofibers grown directly on a silver thin film surface. We show results of both photoluminescence lifetime measurements and angle-resolved leakage radiation spectroscopy in the excitation range 420–620 nm, which corresponds to the material photoluminescence band. The optical characteristics of randomly oriented p-6P nanofibers assembled directly on the metal surface are remarkably comparable to those of fibers grown on crystalline substrate surfaces. In addition, compared to mica-transferred fibers, the photoluminescence lifetime is longer. More importantly, they show polarization-insensitive plasmonic activity and are entirely consistent with theoretical predictions. Both analytical and numerical finite-difference time-domain simulations support the experimental data. Our findings open a new avenue for incorporating organic nanofibers into optoelectronic applications by directly depositing the p-6P material onto selected substrates. This direct deposition significantly reduces the deformation of the fiber structure and the impurity introduction, usually implied by the transfer process.