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Chains of coupled metallic nanoparticles are of special interest for plasmonic applications because they can sustain highly dispersive plasmon bands, allowing strong ballistic plasmon wave transport. Whereas early studies focused on homogeneous particle chains exhibiting only one dominant band, heterogeneous assemblies consisting of different nanoparticle species came into the spotlight recently. Their increased configuration space principally allows engineering multiple bands, bandgaps, or topological states. Simultaneously, the challenge of the precise arrangement of nanoparticles, including their distances and geometric patterns, as well as the precise characterization of the plasmonics in these systems, persists. Here, the surface plasmon resonances in heterogeneous AgAu nanoparticle chains are reported. Wrinkled templates are used for directed self‐assembly of monodisperse gold and silver nanospheres as chains, which allows assembling statistical combinations of more than 109 particles. To reveal the spatial and spectral distribution of the plasmonic response, state‐of‐the‐art scanning transmission electron microscopy coupled with electron energy loss spectroscopy accompanied by boundary element simulations is used. A variety of modes in the heterogeneous chains are found, ranging from localized surface plasmon modes occurring in single gold or silver spheres, respectively, to modes that result from the hybridization of the single particles. This approach opens a novel avenue toward combinatorial studies of plasmonic properties in heterosystems. [ABSTRACT FROM AUTHOR]

Recently, N‐heterocyclic carbenes (NHCs) are explored as anchor groups to bind organic ligands to colloidal gold (i.e. gold nanoparticles, Au NPs), yet these efforts are confined to non‐conjugated ligands so far—that is, focused solely on exploiting the stability aspect. Using NHCs to link Au NPs and electronically active organic components, for example, conjugated polymers (CPs), will allow capitalizing on both the stability as well as the inherent conductivity of the NHC anchors. Here, we report three types of Br‐NHC‐Au‐X (X=Cl, Br) complexes, which, when used as starting points for Kumada polymerizations, yield regioregular poly(3‐hexylthiophenes)‐NHC‐Au (P3HTs‐NHC‐Au) with narrow molecular weight distributions. The corresponding NPs are obtained via direct reduction and show excellent thermal as well as redox stability. The NHC anchors enable electron delocalization over the gold/CP interface, resulting in an improved electrochromic response behavior in comparison with P3HT‐NHC‐Au. [ABSTRACT FROM AUTHOR]

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We review the field of organic–inorganic nanocomposites with a focus on materials that exhibit a significant degree of electronic coupling across the hybrid interface. These nanocomposites undergo a variety of charge and energy transfer processes, enabling optoelectronic applications in devices which exploit singlet fission, triplet energy harvesting, photon upconversion or hot charge carrier transfer. We discuss the physical chemistry of the most common organic and inorganic components. Based on those we derive synthesis and assembly strategies and design criteria on material and device level with a focus on photovoltaics, spin memories or optical upconverters. We conclude that future research in the field should be directed towards an improved understanding of the binding motif and molecular orientation at the hybrid interface. [ABSTRACT FROM AUTHOR]

Dieser Aufsatz befasst sich mit dem Bereich der organisch‐anorganischen Nanokomposite, wobei der Schwerpunkt auf Materialien liegt, die einen signifikanten Grad elektronischer Kopplung über die Hybridgrenzfläche aufweisen. Diese Nanokomposite durchlaufen verschiedenste Ladungs‐ und Energietransferprozesse und ermöglichen optoelektronische Anwendungen in Bauelementen, welche auf der Nutzung von Singulettspaltung, der Gewinnung von Triplett‐Exzitonen, der Photonen‐Aufwärtskonvertierung oder dem Transfer heißer Ladungsträger beruhen. Wir diskutieren die physikalische Chemie der gängigsten organischen und anorganischen Komponenten. Ausgehend davon entwickeln wir Synthese‐ und Assemblierungsstrategien sowie Designkriterien auf Material‐ und Bauelementebene, mit Hinblick auf Photovoltaik, Spin‐Speicher und optischen Hochkonvertern. Die vorgestellten Ergebnisse legen nahe, dass die zukünftige Forschung auf diesem Gebiet auf ein besseres Verständnis des Bindungsmotivs und der molekularen Orientierung an der Hybridgrenzfläche ausgerichtet werden sollte. [ABSTRACT FROM AUTHOR]

We present a fluorescent emitter (rhodamine B) coupled to a dielectric or metallic interface as well as a metallic cavity to study their radiative decay processes. Supported by finite-difference time-domain (FDTD) simulations, we correlate the non-radiative and radiative decay rates with the absorption and scattering cross section efficiencies, respectively. On a single particle level, we use atomic force microscopy (AFM), scanning electron microscopy (SEM), scattering spectroscopy, fluorescence life time imaging (FLIM) and time-correlated single photon counting (TCSPC) to evaluate the enhanced fluorescence decay at the same location. With this study, we show a colloidal gain material, which can be integrated into lattices using existing directed self-assembled methods to study their coherent energy transfer. [ABSTRACT FROM AUTHOR]

Bis heute war es nicht möglich, die optische Güte von Silbernanopartikeln mit Eigenschaften wie chemischer Stabilität, Oberflächenmodifizierbarkeit und kontrollierter Synthese in Verbindung zu bringen. Wir präsentieren eine Synthesemethode, die zukünftige Entwicklungen in Informations‐, Energie‐ und Medizintechnologie ermöglicht, in denen optische oder elektronische Eigenschaften eine zentrale Rolle spielen. Dafür kombinieren wir die goldtypischen Eigenschaften mit der Plasmonik von Silber in einem rein wasserbasierten Au/Ag/Au‐Kern‐Schale‐Schale‐System. Die Dispersität der Nanopartikel wird durch maskierte Goldkerne vorgegeben, wobei die Optik von Silber bestimmt wird. Die Überwachsung mit einer sehr dünnen, schützenden Goldschicht verleiht Oxidationsstabilität und Oberflächenfunktionalität, ohne die optischen Eigenschaften des Silbers zu beeinträchtigen. Damit werden die optische Güte von Silber und die chemische Stabilität von Gold vereint – ohne Limitierung auf eine Morphologie. Optische Güte und chemische Stabilität: In einem allgemeinen Syntheseansatz wird die Dispersität durch die maskierten Goldkerne vorgegeben, während die Optik von Silber bestimmt wird. Die erneute Überwachsung mit einer sehr dünnen, schützenden Goldschicht ermöglicht Oxidationsstabilität und Oberflächenfunktionalität, ohne die durch Silber gewonnenen optischen Eigenschaften zu beeinträchtigen. [ABSTRACT FROM AUTHOR]

To date, it has not been possible to combine the high optical quality of silver particles with the good chemical stability and synthetic convenience in a fully aqueous system, while simultaneously allowing chemical surface functionalization. We present a synthetic pathway for future developments in information, energy and medical technology where strong optical/electronic properties are crucial. Therefore, the advantages inherent to gold are fused with the plasmonic properties of silver in a fully aqueous Au/Ag/Au core-shell shell system. These nanoparticles inherit low dispersity from their masked gold cores, yet simultaneously exhibit the strong plasmonic properties of silver. Protecting the silver surface with a thin gold layer enables oxidant stability and functionality without altering the Ag-controlled optical properties. This combines both worlds-optical quality and chemical stability-and is not limited to a specific particle shape. [ABSTRACT FROM AUTHOR]

Recently, N-heterocyclic carbenes (NHCs) are explored as anchor groups to bind organic ligands to colloidal gold (i.e. gold nanoparticles, Au NPs), yet these efforts are confined to non-conjugated ligands so far-that is, focused solely on exploiting the stability aspect. Using NHCs to link Au NPs and electronically active organic components, for example, conjugated polymers (CPs), will allow capitalizing on both the stability as well as the inherent conductivity of the NHC anchors. Here, we report three types of Br-NHC-Au-X (X=Cl, Br) complexes, which, when used as starting points for Kumada polymerizations, yield regioregular poly(3-hexylthiophenes)-NHC-Au (P3HTs-NHC-Au) with narrow molecular weight distributions. The corresponding NPs are obtained via direct reduction and show excellent thermal as well as redox stability. The NHC anchors enable electron delocalization over the gold/CP interface, resulting in an improved electrochromic response behavior in comparison with P3HT-NHC-Au., (© 2020 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

We investigate the formation of chains of few plasmonic nanoparticles-so-called plasmonic oligomers-by strain-induced fragmentation of linear particle assemblies. Detailed investigations of the fragmentation process are conducted by in situ atomic force microscopy and UV-vis-NIR spectroscopy. Based on these experimental results and mechanical simulations computed by the lattice spring model, we propose a formation mechanism that explains the observed decrease of chain polydispersity upon increasing strain and provides experimental guidelines for tailoring chain length distribution. By evaluation of the strain-dependent optical properties, we find a reversible, nonlinear shift of the dominant plasmonic resonance. We could quantitatively explain this feature based on simulations using generalized multiparticle Mie theory (GMMT). Both optical and morphological characterization show that the unstrained sample is dominated by chains with a length above the so-called infinite chain limit-above which optical properties show no dependency on chain length-while during deformation, the average chain length decrease below this limit and chain length distribution becomes more narrow. Since the formation mechanism results in a well-defined, parallel orientation of the oligomers on macroscopic areas, the effect of finite chain length can be studied even using conventional UV-vis-NIR spectroscopy. The scalable fabrication of oriented, linear plasmonic oligomers opens up additional opportunities for strain-dependent optical devices and mechanoplasmonic sensing.

We present a bottom-up assembly route for a large-scale organization of plasmonic nanoparticles (NPs) into three-dimensional (3D) modular assemblies with core/satellite structure. The protein-assisted assembly of small spherical gold or silver NPs with a hydrophilic protein shell (as satellites) onto larger metal NPs (as cores) offers high modularity in sizes and composition at high satellite coverage (close to the jamming limit). The resulting dispersions of metal/metal nanoclusters exhibit high colloidal stability and therefore allow for high concentrations and a precise characterization of the nanocluster architecture in dispersion by small-angle X-ray scattering (SAXS). Strong near-field coupling between the building blocks results in distinct regimes of dominant satellite-to-satellite and core-to-satellite coupling. High robustness against satellite disorder was proved by UV/vis diffuse reflectance (integrating sphere) measurements. Generalized multiparticle Mie theory (GMMT) simulations were employed to describe the electromagnetic coupling within the nanoclusters. The close correlation of structure and optical property allows for the rational design of core/satellite nanoclusters with tailored plasmonics and well-defined near-field enhancement, with perspectives for applications such as surface-enhanced spectroscopies.