Plasmonic sphere-on-plane systems with semiconducting polymer spacer layers

Abstract

The optical properties of metal-film-coupled nanoparticles (NPs) are highly sensitive to physical and optical interactions between the NPs and the spacer medium in the gap between the NP and metal film. Here, we investigate the physical and optical interactions between gold NPs (AuNPs) and semiconducting conjugated polymer thin-film spacers in a "sphere-on-plane" type metal-film-coupled NP system, and their influence on the plasmonic scattering of individual AuNPs. We choose two different conjugated polymers: one with an absorption spectrum that is resonant with the plasmonic modes of the AuNPs and another that is non-resonant. By correlating dark-field back-scattering optical images with topographic atomic force microscope images, we find that partial embedding of the AuNPs occurs in both conjugated polymers to different extents. This can lead to partial quenching of certain plasmonic scattering modes, which results in a change of the back-scattering colors from the AuNPs. Pronounced, red-shifted scattering is observed due to deep embedding of the AuNPs, particularly for thicker conjugated polymer spacers that have resonant absorption with the plasmonic modes of the AuNPs. Polarization-controlled defocused dark-field imaging is employed to visualize the emergence of horizontally-polarized scattering modes upon embedding of AuNPs into the conjugated polymer spacer. These results demonstrate the importance of nanoparticle-spacer physical interactions to the control of the color and polarization of coupled plasmonic modes in nanoparticle-film systems relevant.

Plasmonic Coupling Architectures for Enhanced Photocatalysis

“…For example, poly(3‐hexylthiophene) as a resonant absorptive layer is beneficial to the coupling between Au NPs and Au film, while the non‐resonant poly(9,9‐dioctylfuorene) layer does not show influence on this coupling. [ 83 ] Plasmonic coupling frequencies of core–shell nanostructures are determined by the dielectric spacer layer and the plasmonic resonances of the individual components. [ 76 ] The experimental and simulation studies have proved that the redshift magnitude of the LSPR band in core–shell nanostructures increases linearly with the increase of ε m .…”

Plasmon-Coupled Resonance Energy Transfer II: Exploring the Peaks and Dips in the Electromagnetic Coupling Factor

“…In recent years, experimental and computational techniques have advanced significantly in studies of different types of plasmons, such as surface plasmon polaritons, localized surface plasmons (LSPs), and lattice plasmons. These advances enable potential applications and provide deep understanding in several fields, including surface-enhanced Raman spectroscopy, − plasmonic lasers, − chemical and biological sensing, ,− and light energy conversion. − …”

Probing the Evolution of Molecular Packing Underlying HJ-Aggregate Transition in Organic Semiconductors Using Solvent Vapor Annealing

“…Defocused emission pattern imaging is an optical technique whereby a phase aberration of ∼1–2 optical wavelengths is introduced by translation of a high-numerical aperture objective (>1.3 NA). , This phase-aberration produces an image which can be understood in terms of the distribution of k -vectors (and resulting constructive/destructive interference at the detector plane) in emission from the system. , The measured emission patterns readily distinguish between isotropic emitters (i.e., disordered systems), single (or multiple highly aligned) dipole emitters, ,, or 2D dipole systems whose orientations are defined by the dipole orientation in all three ( x , y , and z ) spatial dimensions. This is a powerful technique that has been used to probe 3D rotation of single molecules in polymer-supported films, , semiconducting polymer nanoparticles, − and quantum dots. ,− We used defocused emission as a means to complement the polarization contrast measurements specifically to assess out-of-plane dipole component, and 2D dipole character.…”