Bright Light Emission and Waveguiding in Conjugated Polymer Nanofibers Electrospun from Organic Salt Added Solutions

Abstract

Light-emitting electrospun nanofibers of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(N,N′-diphenyl)-N,N′-di(p-butyl-oxy-phenyl)-1,4-diaminobenzene)] (PFO–PBAB) are produced by electrospinning under different experimental conditions. In particular, uniform fibers with average diameter of 180 nm are obtained by adding an organic salt to the electrospinning solution. The spectroscopic investigation assesses that the presence of the organic salt does not alter the optical properties of the active material, therefore providing an alternative approach for the fabrication of highly emissive conjugated polymer nanofibers. The produced nanofibers display self-waveguiding of light, and polarized photoluminescence, which is especially promising for embedding active electrospun fibers in sensing and nanophotonic devices.

Origin of high propagation loss in electrospun polymer nanofibers

“…[http://dx.doi.org/10.1063/1.4884217] Nanofibers, which are fibers with diameters less than 1 μm, are attracting considerable attention owing to unique optical interactions that arise from their subwavelength size including guiding, [1][2][3][4][5][6][7] confinement, 8 and amplification. 9,10 These properties make them promising candidates for applications in small optical devices such as waveguides, [1][2][3][4][5][6][7] light sources, 11,12 sensors, 13 resonators, 14 gratings, 15 and switches, 16 and the fibers are also applicable to the field of plasmonics 17 and optomechanics.…”

“…9,10 These properties make them promising candidates for applications in small optical devices such as waveguides, [1][2][3][4][5][6][7] light sources, 11,12 sensors, 13 resonators, 14 gratings, 15 and switches, 16 and the fibers are also applicable to the field of plasmonics 17 and optomechanics. 18,19 Electrospun polymer fibers have nanometer diameters and high aspect ratios, making them well-suited for use in such optical devices.…”

Graphene-doped polymer nanofibers for low-threshold nonlinear optical waveguiding

“…The laser light was coupled to the nanofiber at different positions to vary propagation length in the nanofiber, and the absorption coefficient was deduced from the exponential decay of the transmitted light and increase in propagation length. The results displayed in Figure 3c yield absorption coefficients of 0.11 dB mm 21 (0.024 mm 21 ) at 633-nm wavelength and 0.069 dB mm 21 (0.016 mm 21 ) at a 1550-nm wavelength of a G/PVA nanofiber, which are lower than many other functionally doped polymer nanofibers 34,35 ; this is due to the excellent surface quality and relatively low concentration of graphene dopants. For reference, the length-dependent output of a pure PVA nanofiber is also provided, with an absorption coefficient of approximately 0.004 dB mm 21 (0.0001 mm 21 ) at a 1550-nm wavelength.…”

Perspectives: Nanofibers and nanowires for disordered photonics

“…The waveguides formed by nanowires and nanofibers are often sub-wavelength, namely, they transport light at optical frequencies along their longitudinal axis, although their transversal size is well below the corresponding wavelength. 32,33 For single nanofibers, the light-scattering properties can be sketched by considering infinitely long dielectric structures with cylindrical shape, under the Rayleigh-Gans approximation for relatively weak scatterers-as in the organic case-which requires |n 1| 1 and kR|n 1| 1. 34 The corresponding form factor, f (θ), which describes the angular distribution of the scattered intensity, is plotted in Figs. 2(a) and 2(b) for the case of incoming light at normal incidence with respect to the fiber longitudinal axis.…”