Chemical Interface Damping Controlled by Interfacial Linkers in Plasmonic Nanoparticle-Polyaniline Hybrids

Abstract Metal nanoparticle-conductive polymer hybrids combine strong light absorption, functional tunability, and pathways for energy and charge transfer, yet linker-specific plasmon damping remains poorly understood. Here, single-particle hyperspectral imaging quantifies plasmon resonance energies and homogeneous line widths in gold nanoparticles (AuNPs), AuNP-polyaniline (PANI), AuNP-4-aminothiophenol (ATP)-PANI, and AuNP-N-heterocyclic carbene (NHC)-PANI hybrids. PANI produces the plasmon red-shift, whereas chemisorbed ATP and NHC linkers induce further red-shifts and pronounced chemical interface damping (CID). AuNP-PANI establishes a CID baseline dominated by plasmon-induced resonance energy transfer (PIRET) to PANI, a contribution also present in both linked hybrids. Beyond the PIRET contributions, the additional damping is assigned to linker-specific plasmon-induced interfacial charge transfer: resonant electron transfer from Au into unoccupied ATP-derived states and resonant hole transfer involving occupied NHC-derived states near the Au Fermi level. Favorable hole transfer alignment and conductive Au–C bridging are consistent with the slightly larger CID of NHC-linked hybrids. These results connect interfacial bonding motifs to distinct plasmon damping pathways and identify interfacial chemistry as a design parameter for plasmon energy extraction.