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Shell-dependent blinking behavior and fluorescence dynamics of single ZnSe/CdS core/shell quantum dots

Abstract

Understanding of blinking behavior and photodynamics is crucial for improving the optical properties of quantum dots (QDs). Here we report the emission blinking behavior and dynamical mechanisms of single ZnSe/CdS core/shell QDs with the shell thickness varying from 1 to 6 monolayers. We find that the emission blinking behavior can be efficiently suppressed in single-exciton regime, and that the photoluminescence (PL) quantum yields (QY) and the corresponding fraction-bright of ZnSe/CdS QDs can be optimized by regulating the shell thickness. Specifically, the PL QY reaches a maximum of 93% when the shell thickness is 4 monolayers. The intensity-resolved and time-resolved fluorescence dynamics of single QD indicate that three exciton decay pathways via trion emission, band-edge emission and shallow surface trap-state emission contribute to the blinking behavior of ZnSe/CdS QDs. The competitive contribution ratios of these three decay components are responsible for the significant difference in emission properties of ZnSe/CdS QD with different shell thickness. Our findings in this work demonstrate that an effective way to improve the quantum yields and fraction-bright of core/shell QD is to enhance the band-edge emission while suppressing the trion emission and surface trap-state emission.

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Publication details

The article was received on 21 Aug 2018, accepted on 04 Sep 2018 and first published on 04 Sep 2018


Article type: Paper
DOI: 10.1039/C8NR06749J
Citation: Nanoscale, 2018, Accepted Manuscript
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    Shell-dependent blinking behavior and fluorescence dynamics of single ZnSe/CdS core/shell quantum dots

    X. Guo, Y. Kuang, S. Wang, Z. Li, H. Shen and L. Guo, Nanoscale, 2018, Accepted Manuscript , DOI: 10.1039/C8NR06749J

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