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Title: Ligand-surface interactions and surface oxidation of colloidal PbSe quantum dots revealed by thin-film positron annihilation methods

Positron Two Dimensional Angular Correlation of Annihilation Radiation (2D-ACAR) measurements reveal modifications of the electronic structure and composition at the surfaces of PbSe quantum dots (QDs), deposited as thin films, produced by various ligands containing either oxygen or nitrogen atoms. In particular, the 2D-ACAR measurements on thin films of colloidal PbSe QDs capped with oleic acid ligands yield an increased intensity in the electron momentum density (EMD) at high momenta compared to PbSe quantum dots capped with oleylamine. Moreover, the EMD of PbSe QDs is strongly affected by the small ethylenediamine ligands, since these molecules lead to small distances between QDs and favor neck formation between near neighbor QDs, inducing electronic coupling between neighboring QDs. The high sensitivity to the presence of oxygen atoms at the surface can be also exploited to monitor the surface oxidation of PbSe QDs upon exposure to air. Finally, our study clearly demonstrates that positron annihilation spectroscopy applied to thin films can probe surface transformations of colloidal semiconductor QDs embedded in functional layers.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [2] ;  [3] ;  [1] ;  [4] ;  [4]
  1. Delft Univ. of Technology (Netherlands). Dept. of Radiation Science and Technology. Faculty of Applied Sciences
  2. Delft Univ. of Technology (Netherlands). Dept. of Chemical Engineering. Faculty of Applied Sciences
  3. Toyota Motor Europe, Zaventem (Belgium). Materials Research and Development
  4. Northeastern Univ., Boston, MA (United States). Dept. of Physics
Publication Date:
Grant/Contract Number:
FG02-07ER46352; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 108; Journal Issue: 8; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Northeastern Univ., Boston, MA (United States); Delft Univ. of Technology (Netherlands); Toyota Motor Europe, Zaventem (Belgium)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Ministry of Economic Affairs (Netherlands); Toyota Motor Europe; China Scholarship Council (CSC)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; ligands; electronic coupling; thin films; chemical elements; materials treatment; solar cells; positron annihilation spectroscopy; angular correlation; annihilation radiation; leptons
OSTI Identifier:
1470084
Alternate Identifier(s):
OSTI ID: 1239170

Shi, Wenqin, Eijt, Stephan W. H., Suchand Sandeep, C. S., Siebbeles, Laurens D. A., Houtepen, Arjan J., Kinge, Sachin, Brück, Ekkes, Barbiellini, Bernardo, and Bansil, Arun. Ligand-surface interactions and surface oxidation of colloidal PbSe quantum dots revealed by thin-film positron annihilation methods. United States: N. p., Web. doi:10.1063/1.4942609.
Shi, Wenqin, Eijt, Stephan W. H., Suchand Sandeep, C. S., Siebbeles, Laurens D. A., Houtepen, Arjan J., Kinge, Sachin, Brück, Ekkes, Barbiellini, Bernardo, & Bansil, Arun. Ligand-surface interactions and surface oxidation of colloidal PbSe quantum dots revealed by thin-film positron annihilation methods. United States. doi:10.1063/1.4942609.
Shi, Wenqin, Eijt, Stephan W. H., Suchand Sandeep, C. S., Siebbeles, Laurens D. A., Houtepen, Arjan J., Kinge, Sachin, Brück, Ekkes, Barbiellini, Bernardo, and Bansil, Arun. 2016. "Ligand-surface interactions and surface oxidation of colloidal PbSe quantum dots revealed by thin-film positron annihilation methods". United States. doi:10.1063/1.4942609. https://www.osti.gov/servlets/purl/1470084.
@article{osti_1470084,
title = {Ligand-surface interactions and surface oxidation of colloidal PbSe quantum dots revealed by thin-film positron annihilation methods},
author = {Shi, Wenqin and Eijt, Stephan W. H. and Suchand Sandeep, C. S. and Siebbeles, Laurens D. A. and Houtepen, Arjan J. and Kinge, Sachin and Brück, Ekkes and Barbiellini, Bernardo and Bansil, Arun},
abstractNote = {Positron Two Dimensional Angular Correlation of Annihilation Radiation (2D-ACAR) measurements reveal modifications of the electronic structure and composition at the surfaces of PbSe quantum dots (QDs), deposited as thin films, produced by various ligands containing either oxygen or nitrogen atoms. In particular, the 2D-ACAR measurements on thin films of colloidal PbSe QDs capped with oleic acid ligands yield an increased intensity in the electron momentum density (EMD) at high momenta compared to PbSe quantum dots capped with oleylamine. Moreover, the EMD of PbSe QDs is strongly affected by the small ethylenediamine ligands, since these molecules lead to small distances between QDs and favor neck formation between near neighbor QDs, inducing electronic coupling between neighboring QDs. The high sensitivity to the presence of oxygen atoms at the surface can be also exploited to monitor the surface oxidation of PbSe QDs upon exposure to air. Finally, our study clearly demonstrates that positron annihilation spectroscopy applied to thin films can probe surface transformations of colloidal semiconductor QDs embedded in functional layers.},
doi = {10.1063/1.4942609},
journal = {Applied Physics Letters},
number = 8,
volume = 108,
place = {United States},
year = {2016},
month = {2}
}