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Ripening of Semiconductor Nanoplatelets

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Ott Florian D., Riedinger Andreas, Ochsenbein David R., Knüsel Philippe N., Erwin Steven C., Mazzotti Marco, Norris David J.,
Project Electronic Impurity Doping of Semiconductor Nanocrystals
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Original article (peer-reviewed)

Journal Nano Letters
Volume (Issue) 17(11)
Page(s) 6870 - 6877
Title of proceedings Nano Letters
DOI 10.1021/acs.nanolett.7b03191

Open Access

URL https://pubs.acs.org/doi/pdf/10.1021/acs.nanolett.7b03191
Type of Open Access Publisher (Gold Open Access)

Abstract

Ostwald ripening describes how the size distribution of colloidal particles evolves with time due to thermodynamic driving forces. Typically, small particles shrink and provide material to larger particles, which leads to size defocusing. Semiconductor nanoplatelets, thin quasi-two dimensional (2D) particles with thicknesses of only a few atomic layers but larger lateral dimensions, offer a unique system to investigate this phenomenon. Experiments show that the distribution of nanoplatelet thicknesses does not defocus during ripening, but instead jumps sequentially from m to (m + 1) monolayers, allowing precise thickness control. We investigate how this counterintuitive process occurs in CdSe nanoplatelets. We develop a microscopic model that treats the kinetics and thermodynamics of attachment and detachment of monomers as a function of their concentration. We then simulate the growth process from nucleation through ripening. For a given thickness, we observe Ostwald ripening in the lateral direction, but none perpendicular. Thicker populations arise instead from nuclei that capture material from thinner nanoplatelets as they dissolve laterally. Optical experiments that attempt to track the thickness and lateral extent of nanoplatelets during ripening appear consistent with these conclusions. Understanding such effects can lead to better synthetic control, enabling further exploration of quasi-2D nanomaterials.
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