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

Journal Article · Tue Jan 03 00:00:00 EST 2017 · Nano Letters

DOI:https://doi.org/10.1021/acs.nanolett.6b03874· OSTI ID:1337889

Park, Samuel D. ^[1]; Baranov, Dmitry  ^[1]; Ryu, Jisu ^[1]; Cho, Byungmoon ^[1]; Halder, Avik; Seifert, Sönke; Vajda, Stefan ; Jonas, David M.  ^[1]

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1. Department of Chemistry and Biochemistry and Renewable and Sustainable Energy Institute, University of Colorado, Boulder, Colorado 80309, United States

Femtosecond two-dimensional Fourier transform spectroscopy is used to determine the static bandgap inhomogeneity of a colloidal PbSe quantum dot ensemble. 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. Lastly, the absorption bandgap inhomogeneity quantitatively agrees with the bandgap variations calculated from the size and shape distribution, placing upper bounds on any surface contributions.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of Colorado, Boulder, CO (United States); Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: FG02-07ER15912; AC02- 06CH11357; AC04-94AL85000; AC02-06CH11357
• OSTI ID: 1337889
• Alternate ID(s): OSTI ID: 1338409; OSTI ID: 1344807; OSTI ID: 1346934
• Report Number(s): SAND-2016-12917J
• Journal Information: Nano Letters, Journal Name: Nano Letters Vol. 17 Journal Issue: 2; ISSN 1530-6984
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

47 OTHER INSTRUMENTATION
Quantum dots
inhomogeneity
size dispersion
shape dispersion
2D spectroscopy
line width
36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
quantum dots
linewidth