Fundamental aspects of nucleation and growth in the solution-phase synthesis of germanium nanocrystals

Abstract
Colloidal Ge nanocrystals (NCs) were synthesized via the solution phase reduction of germanium(ii) iodide. We report a systematic investigation of the nanocrystal nucleation and growth as a function of synthesis conditions including the nature of coordinating solvents, surface bound ligands, synthesis duration and temperature. NC synthesis in reaction environments with weakly bound phosphine surface ligand led to the coalescence of nascent particles leading to ensembles with broad lognormal particle diameter distributions. Synthesis in the presence of amine or alkene ligands mitigated particle coalescence. High-resolution transmission electron micrographs revealed that NCs grown in the presence of weak ligands had a high crystal defect density whereas NCs grown in amine solutions were predominantly defect-free. We applied infrared spectroscopy to study the NC surface chemistry and showed that alkene ligands project the NCs from surface oxidation. Photoluminescence spectroscopy measurements showed that alkene ligands passivate surface traps, as indicated by infrared fluorescence, conversely oxidized phosphine and amine passivated NCs did not fluoresce. © 2010 The Royal Society of Chemistry.

Citation
Codoluto SC, Baumgardner WJ, Hanrath T (2010) Fundamental aspects of nucleation and growth in the solution-phase synthesis of germanium nanocrystals. CrystEngComm 12: 2903. Available: http://dx.doi.org/10.1039/c002820g.

Acknowledgements
This work was supported in part by NSF CBET 0828703 and the KAUST-CU center. TEM and SEM measurements were performed at the Cornell Center for Materials Research. We thank J.J. Choi for assistance with the photoluminescence measurements.

Publisher
Royal Society of Chemistry (RSC)

Journal
CrystEngComm

DOI
10.1039/c002820g

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