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Bandgap Inhomogeneity of a PbSe Quantum Dot Ensemble from Two-Dimensional Spectroscopy and Comparison to Size Inhomogeneity from Electron Microscopy

Park, Samuel D. ; Baranov, Dmitry LU orcid ; Ryu, Jisu ; Cho, Byungmoon ; Halder, Avik ; Seifert, Sönke ; Vajda, Stefan and Jonas, David M. (2017) In Nano Letters 17(2). p.762-771
Abstract

Femtosecond two-dimensional Fourier transform spectroscopy is used to determine the static bandgap inhomogeneity of a colloidal quantum dot ensemble. The excited states of quantum dots absorb light, so their absorptive two-dimensional (2D) spectra will typically have positive and negative peaks. It is shown that the absorption bandgap inhomogeneity is robustly determined by the slope of the nodal line separating positive and negative peaks in the 2D spectrum around the bandgap transition; this nodal line slope is independent of excited state parameters not known from the absorption and emission spectra. The absorption bandgap inhomogeneity is compared to a size and shape distribution determined by electron microscopy. The electron... (More)

Femtosecond two-dimensional Fourier transform spectroscopy is used to determine the static bandgap inhomogeneity of a colloidal quantum dot ensemble. The excited states of quantum dots absorb light, so their absorptive two-dimensional (2D) spectra will typically have positive and negative peaks. It is shown that the absorption bandgap inhomogeneity is robustly determined by the slope of the nodal line separating positive and negative peaks in the 2D spectrum around the bandgap transition; this nodal line slope is independent of excited state parameters not known from the absorption and emission spectra. The absorption bandgap inhomogeneity is compared to a size and shape distribution determined by electron microscopy. The electron microscopy images are analyzed using new 2D histograms that correlate major and minor image projections to reveal elongated nanocrystals, a conclusion supported by grazing incidence small-angle X-ray scattering and high-resolution transmission electron microscopy. The absorption bandgap inhomogeneity quantitatively agrees with the bandgap variations calculated from the size and shape distribution, placing upper bounds on any surface contributions.

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author
; ; ; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
keywords
2D spectroscopy, inhomogeneity, line width, Quantum dots, shape dispersion, size dispersion
in
Nano Letters
volume
17
issue
2
pages
10 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:28045274
  • scopus:85011965812
ISSN
1530-6984
DOI
10.1021/acs.nanolett.6b03874
language
English
LU publication?
no
additional info
Publisher Copyright: © 2017 American Chemical Society.
id
f38a3a46-1a90-4acf-81ef-3021ec1b4b43
date added to LUP
2023-01-17 13:54:52
date last changed
2024-05-30 12:21:23
@article{f38a3a46-1a90-4acf-81ef-3021ec1b4b43,
  abstract     = {{<p>Femtosecond two-dimensional Fourier transform spectroscopy is used to determine the static bandgap inhomogeneity of a colloidal quantum dot ensemble. The excited states of quantum dots absorb light, so their absorptive two-dimensional (2D) spectra will typically have positive and negative peaks. It is shown that the absorption bandgap inhomogeneity is robustly determined by the slope of the nodal line separating positive and negative peaks in the 2D spectrum around the bandgap transition; this nodal line slope is independent of excited state parameters not known from the absorption and emission spectra. The absorption bandgap inhomogeneity is compared to a size and shape distribution determined by electron microscopy. The electron microscopy images are analyzed using new 2D histograms that correlate major and minor image projections to reveal elongated nanocrystals, a conclusion supported by grazing incidence small-angle X-ray scattering and high-resolution transmission electron microscopy. The absorption bandgap inhomogeneity quantitatively agrees with the bandgap variations calculated from the size and shape distribution, placing upper bounds on any surface contributions.</p>}},
  author       = {{Park, Samuel D. and Baranov, Dmitry and Ryu, Jisu and Cho, Byungmoon and Halder, Avik and Seifert, Sönke and Vajda, Stefan and Jonas, David M.}},
  issn         = {{1530-6984}},
  keywords     = {{2D spectroscopy; inhomogeneity; line width; Quantum dots; shape dispersion; size dispersion}},
  language     = {{eng}},
  month        = {{02}},
  number       = {{2}},
  pages        = {{762--771}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Nano Letters}},
  title        = {{Bandgap Inhomogeneity of a PbSe Quantum Dot Ensemble from Two-Dimensional Spectroscopy and Comparison to Size Inhomogeneity from Electron Microscopy}},
  url          = {{http://dx.doi.org/10.1021/acs.nanolett.6b03874}},
  doi          = {{10.1021/acs.nanolett.6b03874}},
  volume       = {{17}},
  year         = {{2017}},
}