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Title: Tuning colloidal quantum dot band edge positions through solution-phase surface chemistry modification

Abstract

Band edge positions of semiconductors determine their functionality in many optoelectronic applications such as photovoltaics, photoelectrochemical cells and light emitting diodes. Here we show that band edge positions of lead sulfide (PbS) colloidal semiconductor nanocrystals, specifically quantum dots (QDs), can be tuned over 2.0 eV through surface chemistry modification. We achieved this remarkable control through the development of simple, robust and scalable solution-phase ligand exchange methods, which completely replace native ligands with functionalized cinnamate ligands, allowing for well-defined, highly tunable chemical systems. By combining experiments and ab initio simulations, we establish clear relationships between QD surface chemistry and the band edge positions of ligand/QD hybrid systems. We find that in addition to ligand dipole, inter-QD ligand shell inter-digitization contributes to the band edge shifts. As a result, we expect that our established relationships and principles can help guide future optimization of functional organic/inorganic hybrid nanostructures for diverse optoelectronic applications.

Authors:
 [1];  [2];  [3];  [4];  [5];  [5]; ORCiD logo [1];  [6];  [2];  [5]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States); Univ. of Colorado, Boulder, CO (United States)
  2. Argonne National Lab. (ANL), Lemont, IL (United States); Univ. of Chicago, Chicago, IL (United States)
  3. Univ. of Chicago, Chicago, IL (United States)
  4. Colorado School of Mines, Golden, CO (United States)
  5. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  6. National Renewable Energy Lab. (NREL), Golden, CO (United States); Colorado School of Mines, Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Energy Frontier Research Center; Center for Advanced Solar Photophysics; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences, and Biosciences Division
OSTI Identifier:
1357948
Alternate Identifier(s):
OSTI ID: 1373584
Report Number(s):
NREL/JA-5900-66738
Journal ID: ISSN 2041-1723
Grant/Contract Number:
AC36-08GO28308; AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; quantum dots; band edge positions; ligand exchange; electronic properties and materials; organic-inorganic nanostructures; chemical synthesis

Citation Formats

Kroupa, Daniel M., Vörös, Márton, Brawand, Nicholas P., McNichols, Brett W., Miller, Elisa M., Gu, Jing, Nozik, Arthur J., Sellinger, Alan, Galli, Giulia, and Beard, Matthew C. Tuning colloidal quantum dot band edge positions through solution-phase surface chemistry modification. United States: N. p., 2017. Web. doi:10.1038/ncomms15257.
Kroupa, Daniel M., Vörös, Márton, Brawand, Nicholas P., McNichols, Brett W., Miller, Elisa M., Gu, Jing, Nozik, Arthur J., Sellinger, Alan, Galli, Giulia, & Beard, Matthew C. Tuning colloidal quantum dot band edge positions through solution-phase surface chemistry modification. United States. doi:10.1038/ncomms15257.
Kroupa, Daniel M., Vörös, Márton, Brawand, Nicholas P., McNichols, Brett W., Miller, Elisa M., Gu, Jing, Nozik, Arthur J., Sellinger, Alan, Galli, Giulia, and Beard, Matthew C. Tue . "Tuning colloidal quantum dot band edge positions through solution-phase surface chemistry modification". United States. doi:10.1038/ncomms15257. https://www.osti.gov/servlets/purl/1357948.
@article{osti_1357948,
title = {Tuning colloidal quantum dot band edge positions through solution-phase surface chemistry modification},
author = {Kroupa, Daniel M. and Vörös, Márton and Brawand, Nicholas P. and McNichols, Brett W. and Miller, Elisa M. and Gu, Jing and Nozik, Arthur J. and Sellinger, Alan and Galli, Giulia and Beard, Matthew C.},
abstractNote = {Band edge positions of semiconductors determine their functionality in many optoelectronic applications such as photovoltaics, photoelectrochemical cells and light emitting diodes. Here we show that band edge positions of lead sulfide (PbS) colloidal semiconductor nanocrystals, specifically quantum dots (QDs), can be tuned over 2.0 eV through surface chemistry modification. We achieved this remarkable control through the development of simple, robust and scalable solution-phase ligand exchange methods, which completely replace native ligands with functionalized cinnamate ligands, allowing for well-defined, highly tunable chemical systems. By combining experiments and ab initio simulations, we establish clear relationships between QD surface chemistry and the band edge positions of ligand/QD hybrid systems. We find that in addition to ligand dipole, inter-QD ligand shell inter-digitization contributes to the band edge shifts. As a result, we expect that our established relationships and principles can help guide future optimization of functional organic/inorganic hybrid nanostructures for diverse optoelectronic applications.},
doi = {10.1038/ncomms15257},
journal = {Nature Communications},
number = ,
volume = 8,
place = {United States},
year = {Tue May 16 00:00:00 EDT 2017},
month = {Tue May 16 00:00:00 EDT 2017}
}

Journal Article:
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Cited by: 8works
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  • Band edge positions of semiconductors determine their functionality in many optoelectronic applications such as photovoltaics, photoelectrochemical cells and light emitting diodes. Here we show that band edge positions of lead sulfide (PbS) colloidal semiconductor nanocrystals, specifically quantum dots (QDs), can be tuned over 2.0 eV through surface chemistry modification. We achieved this remarkable control through the development of simple, robust and scalable solution-phase ligand exchange methods, which completely replace native ligands with functionalized cinnamate ligands, allowing for well-defined, highly tunable chemical systems. By combining experiments and ab initio simulations, we establish clear relationships between QD surface chemistry and the bandmore » edge positions of ligand/QD hybrid systems. We find that in addition to ligand dipole, inter-QD ligand shell inter-digitization contributes to the band edge shifts. We expect that our established relationships and principles can help guide future optimization of functional organic/inorganic hybrid nanostructures for diverse optoelectronic applications.« less
  • Colloidal quantum dots (CQDs) have received recent attention for low cost, solution processable, high efficiency solid-state photovoltaic devices due to the possibility of tailoring their optoelectronic properties by tuning size, composition, and surface chemistry. However, the device performance is limited by the diffusion length of charge carriers due to recombination. In this work, we show that band engineering of PbS QDs is achievable by changing the dipole moment of the passivating ligand molecules surrounding the QD. The valence band maximum and conduction band minimum of PbS QDs passivated with three different thiophenol ligands (4-nitrothiophenol, 4-fluorothiophenol, and 4-methylthiophenol) are determined bymore » UV–visible absorption spectroscopy and photoelectron spectroscopy in air (PESA), and the experimental results are compared with DFT calculations. These band-engineered QDs have been used to fabricate heterojunction solar cells in both unidirectional and bidirectional configurations. The results show that proper band alignment can improve the directionality of charge carrier collection to benefit the photovoltaic performance.« less