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

Journal Article · Wed Dec 11 00:00:00 EST 2019 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/acs.jpcc.9b08006· OSTI ID:1615623

Pelton, Matthew  ^[1]; Wang, Yana ^[2]; Fedin, Igor ^[3]; Talapin, Dmitri V.  ^[4]; O’Leary, Stephen K. ^[2]

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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)

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.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: 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)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1615623
• Journal Information: Journal of Physical Chemistry. C, Vol. 124, Issue 1; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Auger recombination
CdSe
carrier cooling
carrier relaxation
core/shell
nanoplatelets
two-dimensional materials