Controlled Assembly of Anisotropic Noble Metal Nanoparticles and a Semiconductor Quantum Dot for Plasmon-Exciton Coupling

Abstract

The assembly of metal nanoparticles and semiconductor quantum dots into well-defined nanoscale architectures enables exploitation of plasmon-exciton coupling, a phenomenon arising from the interactions between plasmons of metal nanoparticles and excitons of quantum dots. This coupling results in novel optical properties like enhanced photoluminescence, Fano interference, and Rabi splitting, with applications in photonic devices, sensors, and quantum information systems. Precise self-assembly control allows tailoring these features for specific uses in photonics and nanotechnology. Anisotropic gold nanobipyramids (AuBP) and gold nanotriangles (AuNT) offer shape-dependent optical properties, exhibiting strong, geometry-tunable localized surface plasmon resonances (LSPR) for efficient coupling with red-emitting quantum dot’s exciton. Furthermore, liquid/liquid interfacial assembly techniques enable uniform, reproducible nanoarchitectures, enhancing assembly efficiency and providing stable systems for optical testing. This dissertation advances controlled self-assembly techniques for anisotropic gold nanoparticles and quantum dots, focusing on synthesis, functionalization, and assembly. Novel strategies, including functionalization using 6-aminohexanethiol and MeO-PEG-SH for the gold nanoparticles, and activated thioctic acid-NHS for the quantum dots, facilitated efficient linkage of the nanoparticles through covalent bond formation. Interfacial assembly methods yielded colloidal AuNT-QD and AuBP-QD discrete assemblies, characterized using UV-Vis, TEM, and single-particle optical measurements, with observed Fano interference confirming plasmon-exciton coupling. These findings establish a framework for designing nanoparticle assemblies, contributing to advancements towards high-performance photonic devices and quantum technologies