Real-Time in Situ Probing of High-Temperature Quantum Dots Solution Synthesis

Abstract : Understanding the formation mechanism of colloidal nanocrystals is of paramount importance in order to design new nanostructures and synthesize them in a predictive fashion. However, reliable data on the pathways leading from molecular precursors to nanocrystals are not available yet. We used synchrotron-based time-resolved in situ small and wide-angle X-ray scattering to experimentally monitor the formation of CdSe quantum dots synthesized in solution through the heating up of precursors in octadecene at 240 °C. Our experiment yields a complete movie of the structure of the solution from the self-assembly of the precursors to the formation of the quantum dots. We show that the initial cadmium precursor lamellar structure melts into small micelles at 100 °C and that the first CdSe nuclei appear at 218.7 °C. The size distributions and concentration in nanocrystals are measured in a quantitative fashion as a function of time. We show that a short nucleation burst lasting 30 s is followed by a slow decrease of nanoparticle concentration. The rate-limiting process of the quantum dot formation is found to be the thermal activation of selenium.
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Contributor : Benjamin Abécassis <>
Submitted on : Thursday, March 17, 2016 - 11:59:21 AM
Last modification on : Thursday, March 21, 2019 - 2:49:39 PM

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Benjamin Abécassis, Cécile Bouet, Cyril Garnero, Doru Constantin, Nicolas Lequeux, et al.. Real-Time in Situ Probing of High-Temperature Quantum Dots Solution Synthesis. Nano Letters, American Chemical Society, 2015, 15 (4), pp.2620. ⟨http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.5b00199⟩. ⟨10.1021/acs.nanolett.5b00199⟩. ⟨hal-01289808⟩

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