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Sizing up excitons in core–shell quantum dots via shell-dependent photoluminescence blinking

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posted on 2023-06-09, 07:16 authored by Aidan Fisher, Mark Osborne
Semiconductor nanocrystals or quantum dots (QDs) are now widely used across solar cell, display, and bioimaging technologies. While advances in multishell, alloyed, and multinary core–shell QD structures have led to improved light-harvesting and photoluminescence (PL) properties of these nanomaterials, the effects that QD-capping have on the exciton dynamics that govern PL instabilities such as blinking in single-QDs is not well understood. We report experimental measurements of shell-size-dependent absorption and PL intermittency in CdSe-CdS QDs that are consistent with a modified charge-tunnelling, self-trapping (CTST) description of the exciton dynamics in these nanocrystals. By introducing an effective, core-exciton size, which accounts for delocalization of charge carriers across the QD core and shell, we show that the CTST models both the shell-depth-dependent red-shift of the QD band gap and changes in the on/off-state switching statistics that we observe in single-QD PL intensity trajectories. Further analysis of CdSe-ZnS QDs, shows how differences in shell structure and integrity affect the QD band gap and PL blinking within the CTST framework.

History

Publication status

  • Published

File Version

  • Accepted version

Journal

ACS Nano

ISSN

1936-0851

Publisher

American Chemical Society

Issue

8

Volume

11

Page range

7829-7840

Department affiliated with

  • Chemistry Publications

Research groups affiliated with

  • Energy and Materials Chemistry Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2017-07-20

First Open Access (FOA) Date

2018-07-06

First Compliant Deposit (FCD) Date

2017-07-20

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