Nanowire-Intensified MEF in Hybrid Polymer-Plasmonic Electrospun Filaments

TL;DR

This study demonstrates that embedding gold nanoparticles in polymer nanowires significantly enhances fluorescence through localized surface plasmon effects, with the enhancement increasing as the wire diameter decreases, promising for nanoscale optical devices.

Contribution

It reveals a nanowire-specific enhancement of metal-enhanced fluorescence (MEF) that surpasses thin film effects, supported by finite element simulations and ensemble fluorescence calculations.

Findings

MEF is significantly higher in nanowires than in thin films.

Reducing nanowire diameter increases fluorescence enhancement.

Ensemble calculations show potential for doubling emission intensity.

Abstract

Hybrid polymer-plasmonic nanostructures might combine high enhancement of localized fields from metal nanoparticles with light confinement and long-range transport in subwavelength dielectric structures. Here we report on the complex behavior of fluorophores coupling to Au nanoparticles within polymer nanowires, which features localized metal-enhanced fluorescence (MEF) with unique characteristics compared to conventional structures. The intensification effect when the particle is placed in the organic filaments is remarkably higher with respect to thin films of comparable thickness, thus highlighting a specific, nanowire-related enhancement of MEF effects. A dependence on the confinement volume in the dielectric nanowire is also evidenced, with MEF significantly increasing upon reducing the wire diameter. These findings are rationalized by finite element simulations, predicting a position-dependent enhancement of the quantum yield of fluorophores embedded in the fibers. Calculation of the ensemble-averaged fluorescence enhancement unveils the possibility of strongly enhancing the overall emission intensity for structures with size twice the diameter of the embedded metal particles. These new, hybrid fluorescent systems with localized enhanced emission, as well as the general Nanowire-Intensified MEF effect associated to them, are highly relevant for developing nanoscale light-emitting devices with high efficiency and inter-coupled through nanofiber networks, highly sensitive optical sensors, and novel laser architectures.