Abstract
Plexcitonic nanohybrids are plasmonic–excitonic novel materials whose peculiar properties are attracting considerable attention in photonics, solar cells, and sensing. These materials can be synthesized and characterized easily by assembling organic or inorganic dyes on plasmonic nanoparticles as support. However, the main factors controlling the assembly process and the occurrence of the plexcitonic coupling are still unclear. To fill this gap, in this work, we studied the plexciton coupling of 12 different dyes with a series of gold nanourchins with various coatings and sizes. Among 24 combinations tested, we observed the formation of plexcitonic hybrids only in five cases. Most of them had cyanine J-aggregates as excitonic counterparts. Stronger plexcitonic couplings were obtained when nanourchins were coated with an exchangeable citrate capping layer rather than a strong ionic thiols capping layer. We propose that the presence of a strongly bound capping layer, as in this latter case, reduces the effective volume available to the dyes.
Highlights
Plexcitonic nanohybrids, i.e., nanosystems characterized by plasmon−exciton couplings, have gained increasing attention over the last two decades for the fundamental interest they hold and for their potential applications
The lower polarity environment provided by the capping layer seems to favor the plexcitonic coupling by reducing the detuning between the molecular and the plasmonic resonances. These findings suggest that mere electrostatic forces between oppositely charged capping molecules and organic dyes, while important,20 are not enough to establish a strong coupling
In this study we systematically explored the formation of plexcitonic resonances in a library of colloidal hybrids prepared by coupling gold nanourchins and different dyes
Summary
Plexcitonic nanohybrids, i.e., nanosystems characterized by plasmon−exciton couplings, have gained increasing attention over the last two decades for the fundamental interest they hold and for their potential applications These nanomaterials are obtained by combining plasmonic substrates, such as nanostructured surfaces or nanoparticles, with excitonic systems like organic dyes, quantum dots, carbon nanotubes, or 2-dimensional transition-metal dichalcogenides, such as MoS2 or WS2.1−3 The peculiar optical properties of these materials might find application in photovoltaics, sensing, digital data storage, and in the broad field of photonics as a manner to control light−matter interactions at the nanoscale.. NPs are coated with stabilizing species (ions, molecules, or polymers) to prevent their coalescence This coating, called the capping layer, clearly plays a crucial role in controlling the interaction between the NPs and the excitonic part. It influences the self-assembly process by determining the intermolecular forces at play, it affects the distances between NPs and dyes, and it can template different aggregation states of the bound excitonic moieties.
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