Strong electronic coupling in two-dimensional assemblies of colloidal PbSe quantum dots

Kenrick J. Williams, William A. Tisdale, Kurtis S. Leschkies, Greg Haugstad, David J. Norris, Eray S. Aydil, X. Y. Zhu

Research output: Contribution to journalArticle

Abstract

Thin films of colloidal PbSe quantum dots can exhibit very high carrier mobilities when the surface ligands are removed or replaced by small molecules, such as hydrazine. Charge transport in such films is governed by the electronic exchange coupling energy (β) between quantum dots. Here we show that two-dimensional quantum dot arrays assembled on a surface provide a powerful system for studying this electronic coupling. We combine optical spectroscopy with atomic force microscopy to examine the chemical, structural, and electronic changes that occur when a submonolayer of PbSe QDs is exposed to hydrazine. We find that this treatment leads to strong and tunable electronic coupling, with the β value as large as 13 meV, which is 1 order of magnitude greater than that previously achieved in 3D QD solids with the same chemical treatment. We attribute this much enhanced electronic coupling to reduced geometric frustration in 2D films. The strongly coupled quantum dot assemblies serve as both charge and energy sinks. The existence of such coupling has serious implications for electronic devices, such as photovoltaic cells, that utilize quantum dots.

Original languageEnglish (US)
Pages (from-to)1532-1538
Number of pages7
JournalACS Nano
Volume3
Issue number6
DOIs
StatePublished - Jun 23 2009

Keywords

  • Electronic coupling
  • Nanocrystal
  • PbSe
  • Quantum dot solid
  • Two-dimensional

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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  • Cite this

    Williams, K. J., Tisdale, W. A., Leschkies, K. S., Haugstad, G., Norris, D. J., Aydil, E. S., & Zhu, X. Y. (2009). Strong electronic coupling in two-dimensional assemblies of colloidal PbSe quantum dots. ACS Nano, 3(6), 1532-1538. https://doi.org/10.1021/nn9001819