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Colloidal Assembly of Au–Quantum Dot–Au Sandwiched Nanostructures with Strong Plasmon–Exciton Coupling
journal contribution
posted on 2020-03-13, 15:11 authored by Yi Luo, Yongchen Wang, Muqiong Liu, Hua Zhu, Ou Chen, Shengli Zou, Jing ZhaoStrong plasmon–exciton
coupling could occur in hybrid metal–dye/semiconductor
nanostructures, where the fast energy exchange between plasmons and
excitons leads to two new eigenmodes of the system, known as Rabi
splitting. In experiments, strongly coupled nanosystems are difficult
to obtain because they require some strict conditions, such as low
plasmonic damping, small plasmon mode volume, and good spectral overlap.
This work demonstrates strongly coupled metal–semiconductor
nanostructures can be constructed using colloidal assembly. Specifically,
sandwiched Au–quantum dot–Au nanostructures were created
through the assembly of Au nanoparticles and colloidal quantum dots
(QDs). The sizes of the QDs and the assembly conditions were varied
to control the mode volume of the plasmonic cavity formed between
the two Au nanoparticles. With a decreased gap size, Rabi splitting
was observed in both dark-field scattering and fluorescence spectra
of single Au–QD–Au nanostructures. Theoretical simulations
revealed that the strong coupling occurred between the excitons and
the octupolar plasmon modes.