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Title: Hot-Carrier Relaxation in CdSe/CdS Core/Shell Nanoplatelets

Abstract

Here, we present time-resolved photoluminescence (PL) spectroscopy of a series of colloidal CdSe/CdS core/shell nanoplatelets with different core and shell thicknesses. Exciton numbers are determined from the integrated PI, intensities, and carrier temperatures are determined from the high-energy exponential tail of the PL spectra. For times between 10 and 1000 ps, the measured carrier relaxation dynamics are well described by a simple model of Auger reheating: biexcitonic Auger recombination continually increases the average energy of the carriers (while decreasing their number), and this reheating sets a bottleneck to cooling through electron-phonon coupling. For times between 1 and 10 ps, the relaxation dynamics are consistent with electron-phonon coupling, where the bottleneck is now the decay of the longitudinal optical phonon population. Comparison of relaxation dynamics to recombination dynamics reveals changes in the carrier-phonon coupling for shell thicknesses greater than 4 monolayers.

Authors:
ORCiD logo [1];  [2];  [3]; ORCiD logo [4];  [2]
  1. Univ. of Maryland, Baltimore, MD (United States); Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials
  2. Univ. of British Columbia, Kelowna, BC (Canada)
  3. Univ. of Chicago, IL (United States)
  4. Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Univ. of Chicago, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division; Natural Sciences and Engineering Research Council of Canada (NSERC); China Scholarship Council; National Science Foundation (NSF). Directorate for Mathematical and Physical Sciences Division of Materials Research (MPS-DMR)
OSTI Identifier:
1615623
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 124; Journal Issue: 1; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Auger recombination; CdSe; carrier cooling; carrier relaxation; core/shell; nanoplatelets; two-dimensional materials

Citation Formats

Pelton, Matthew, Wang, Yana, Fedin, Igor, Talapin, Dmitri V., and O’Leary, Stephen K.. Hot-Carrier Relaxation in CdSe/CdS Core/Shell Nanoplatelets. United States: N. p., 2019. Web. https://doi.org/10.1021/acs.jpcc.9b08006.
Pelton, Matthew, Wang, Yana, Fedin, Igor, Talapin, Dmitri V., & O’Leary, Stephen K.. Hot-Carrier Relaxation in CdSe/CdS Core/Shell Nanoplatelets. United States. https://doi.org/10.1021/acs.jpcc.9b08006
Pelton, Matthew, Wang, Yana, Fedin, Igor, Talapin, Dmitri V., and O’Leary, Stephen K.. Wed . "Hot-Carrier Relaxation in CdSe/CdS Core/Shell Nanoplatelets". United States. https://doi.org/10.1021/acs.jpcc.9b08006. https://www.osti.gov/servlets/purl/1615623.
@article{osti_1615623,
title = {Hot-Carrier Relaxation in CdSe/CdS Core/Shell Nanoplatelets},
author = {Pelton, Matthew and Wang, Yana and Fedin, Igor and Talapin, Dmitri V. and O’Leary, Stephen K.},
abstractNote = {Here, we present time-resolved photoluminescence (PL) spectroscopy of a series of colloidal CdSe/CdS core/shell nanoplatelets with different core and shell thicknesses. Exciton numbers are determined from the integrated PI, intensities, and carrier temperatures are determined from the high-energy exponential tail of the PL spectra. For times between 10 and 1000 ps, the measured carrier relaxation dynamics are well described by a simple model of Auger reheating: biexcitonic Auger recombination continually increases the average energy of the carriers (while decreasing their number), and this reheating sets a bottleneck to cooling through electron-phonon coupling. For times between 1 and 10 ps, the relaxation dynamics are consistent with electron-phonon coupling, where the bottleneck is now the decay of the longitudinal optical phonon population. Comparison of relaxation dynamics to recombination dynamics reveals changes in the carrier-phonon coupling for shell thicknesses greater than 4 monolayers.},
doi = {10.1021/acs.jpcc.9b08006},
journal = {Journal of Physical Chemistry. C},
number = 1,
volume = 124,
place = {United States},
year = {2019},
month = {12}
}

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