2025/07/18 by Carla Estévez‐Varela, Estévez-Varela, Carla, José Gama +14 · 1 citation
Physics and Astronomy · #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Optics (physics.optics) #Physics of Superconductivity and Magnetism #Spectroscopy and Quantum Chemical Studies #Strong Light-Matter Interactions
paper · pdf · doi:10.48550/arxiv.2507.13784
openalex publication_date 2025/07/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
J-aggregates are promising organic materials for nanophotonic applications due to their excitonic properties and ability to support surface exciton polaritons at room temperature, providing a robust platform for nanoscale light manipulation. While thin films composed of J-aggregates have demonstrated these advantages, colloidal J-aggregate nanoparticles remain underexplored. Herein, we report the synthesis of colloidal J-aggregate flakes by electrostatic interaction of cyanine molecules (TDBC) and oppositely charged polyelectrolytes (polydiallyldimethylammonium chloride, PDDA). These flakes exhibit colloidal stability maintaining the J-aggregate conformation even in solvents that favoured their monomeric state. The characterization of the colloidal J-aggregate flakes reveals their capability to support surface exciton polaritons at room temperature. This was further confirmed at single-particle level by observing an angular-independent Reststrahlen band near the excitonic resonance. In addition, the colloidal flakes exhibit a strong scattering component that broadens the extinction band and redshifts the photoluminescence, indicating that the colloidal architecture influences the optical response. These findings introduce a versatile colloidal system for constructing excitonic nanostructures tailored for advanced photonic applications.