Hot-Carrier Relaxation in CdSe/CdS Core/Shell Nanoplatelets
Links to Fileshttps://pubs.acs.org/doi/abs/10.1021/acs.jpcc.9b08006
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Type of Work7 pages
Citation of Original PublicationPelton, Matthew; Wang, Yana; Fedin, Igor; Talapin, Dmitri V.; O’Leary, Stephen K.; Hot-Carrier Relaxation in CdSe/CdS Core/Shell Nanoplatelets; The Journal of Physical Chemistry 124, 1, 1020-1026 (2019); https://pubs.acs.org/doi/abs/10.1021/acs.jpcc.9b08006
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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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 PL 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.
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