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Excitation Wavelength Dependent Photon Anti-bunching/Bunching from Single Quantum Dots near Gold Nanostructures


In this study, we aim to investigate the change in photon emission statistics of single CdSe/CdS core/shell quantum dots (QDs) on dielectric modified gold nanoparticle (NP) substrates as a function of excitation wavelength. Photons emitted from single QDs are typically “anti-bunched” and are independent of excitation wavelength. However, when QDs are coupled to plasmonic substrates, even at the low excitation power regime, we observed a significant change in photoluminescence emission behavior of single QDs; i. e. the emission transformed from incomplete photon anti-bunched to bunched when the excitation was changed from “off” to “on” plasmon resonance. Theoretical studies based on electrodynamics modeling suggested that for the QD-Au NP system, the quantum yield of single exciton decreases while that of biexciton increases. In addition, when excited at “on” resonance condition, the absorption cross-section is highly enhanced, resulting in an increased population of higher order excitons of the QDs. The higher order exciton emission was directly observed as an additional peak appeared at the blue side of the exciton peak of single QDs. The combined effect of the change in quantum yield and the increase in the absorption cross-section switches the photons emitted by single QDs from anti-bunched to bunched. These results provided direct evidence that not only the plasmonic nanostructures but also the excitation wavelength can effectively control the photon emission statistics of single QDs in hybrid metal-semiconductor system. Manipulating multiexciton-plasmon interaction in hybrid complexes like this could possibly open up new doors for applications such as entangled photon pair generation and plasmon-enhanced optoelectronic devices.

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Publication details

The article was received on 20 Jul 2017, accepted on 04 Dec 2017 and first published on 05 Dec 2017

Article type: Paper
DOI: 10.1039/C7NR05299E
Citation: Nanoscale, 2017, Accepted Manuscript
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    Excitation Wavelength Dependent Photon Anti-bunching/Bunching from Single Quantum Dots near Gold Nanostructures

    S. DEY, Y. Zhou, Y. Sun, J. A. Jenkins, D. A. Kriz, S. L. Suib, C. Ou, S. Zou and J. Zhao, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR05299E

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