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Title: Two-Step Nucleation and Growth of InP Quantum Dots via Magic-Sized Cluster Intermediates

We report on the role of magic-sized clusters (MSCs) as key intermediates in the synthesis of indium phosphide quantum dots (InP QDs) from molecular precursors. These observations suggest that previous efforts to control nucleation and growth by tuning precursor reactivity have been undermined by formation of these kinetically persistent MSCs prior to QD formation. The thermal stability of InP MSCs is influenced by the presence of exogenous bases as well as choice of the anionic ligand set. Addition of a primary amine, a common additive in previous InP QD syntheses, to carboxylate terminated MSCs was found to bypass the formation of MSCs, allowing for homogeneous growth of InP QDs through a continuum of isolable sizes. Substitution of the carboxylate ligand set for a phosphonate ligand set increased the thermal stability of one particular InP MSC to 400°C. The structure and optical properties of the MSCs with both carboxylate and phosphonate ligand sets were studied by UV-Vis absorption spectroscopy, powder XRD analysis, and solution ³¹P{¹H} and ¹H NMR spectroscopy. Finally, the carboxylate terminated MSCs were identified as effective single source precursors (SSPs) for the synthesis of high quality InP QDs. Employing InP MSCs as SSPs for QDs effectively decouples the formationmore » of MSCs from the subsequent second nucleation event and growth of InP QDs. The concentration dependence of this SSP reaction, as well as the shape uniformity of particles observed by TEM suggests that the stepwise growth from MSCs directly to QDs proceeds via a second nucleation event rather than an aggregative growth mechanism.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1]
  1. Univ. of Washington, Seattle, WA (United States). Dept. of Chemistry
  2. Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics
  3. Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics; Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.
Publication Date:
OSTI Identifier:
1182518
Report Number(s):
BNL--107509-2015-JA
Journal ID: ISSN 0897-4756; R&D Project: PM032; KC0202010
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 27; Journal Issue: 4; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Brookhaven National Laboratory (BNL)
Sponsoring Org:
USDOE SC OFFICE OF BASIC ENERGY SCIENCES
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY magic-sized clusters (MSCs), indium phosphide quantum dots (InP QDs)