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  4. Resolving the Core and the Surface of CdSe Quantum Dots and Nanoplatelets Using Dynamic Nuclear Polarization Enhanced PASS-PIETA NMR Spectroscopy
 
research article

Resolving the Core and the Surface of CdSe Quantum Dots and Nanoplatelets Using Dynamic Nuclear Polarization Enhanced PASS-PIETA NMR Spectroscopy

Piveteau, Laura
•
Ong, Ta-Chung
•
Walder, Brennan J.  
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September 26, 2018
Acs Central Science

Understanding the surface of semiconductor nanocrystals (NCs) prepared using colloidal methods is a long-standing goal of paramount importance for all their potential optoelectronic applications, which remains unsolved largely because of the lack of site-specific physical techniques. Here, we show that multidimensional Cd-113 dynamic nuclear polarization (DNP) enhanced NMR spectroscopy allows the resolution of signals originating from different atomic and magnetic surroundings in the NC cores and at the surfaces. This enables the determination of the structural perfection, and differentiation between the surface and core atoms in all major forms of size- and shape-engineered CdSe NCs: irregularly faceted quantum dots (QDs) and atomically flat nanoplatelets, including both dominant polymorphs (zinc-blende and wurtzite) and their epitaxial nanoheterostructures (CdSe/CdS core/shell quantum dots and CdSe/CdS core/crown nanoplatelets), as well as magic-sized CdSe clusters. Assignments of the NMR signals to specific crystal facets of oleate-terminated ZB structured CdSe NCs are proposed. Significantly, we discover far greater atomistic complexity of the surface structure and the species distribution in wurtzite as compared to zinc-blende CdSe QDs, despite an apparently identical optical quality of both QD polymorphs.

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Type
research article
DOI
10.1021/acscentsci.8b00196
Web of Science ID

WOS:000445724800010

Author(s)
Piveteau, Laura
Ong, Ta-Chung
Walder, Brennan J.  
Dirin, Dmitry N.
Moscheni, Daniele
Schneider, Barbara
Baer, Janine
Protesescu, Loredana
Masciocchi, Norberto
Guagliardi, Antonietta
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Date Issued

2018-09-26

Published in
Acs Central Science
Volume

4

Issue

9

Start page

1113

End page

1125

Subjects

Chemistry, Multidisciplinary

•

Chemistry

•

solid-state nmr

•

side-band separation

•

magic-angle

•

semiconductor nanocrystals

•

magnetic-resonance

•

solar-cells

•

mas nmr

•

trioctylphosphine oxide

•

colloidal nanocrystals

•

ligand-exchange

Note

This is an open access article under the terms of the Creative Commons Attribution License

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LRM  
ISIC-GE  
Available on Infoscience
December 13, 2018
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/152743
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