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Title: Ultrafast hole relaxation dynamics in quantum dots revealed by two-dimensional electronic spectroscopy

Journal Article · · Communications Physics

Elucidating the population dynamics of correlated electron-hole pairs (bound excitons) in semiconducting quantum dots (QDs) is key for developing our fundamental understanding of nanoscale photophysics as well as for the optimal design of devices, such as lasers. For decades, it was assumed that holes did not contribute to band edge bleach signals in QDs. Here, we employ two-dimensional electronic spectroscopy to monitor electron and hole dynamics in both CdSe and CdSe/CdS/ZnS QDs to probe electron and hole dynamics. Based on a combination of time and frequency resolution, we observe a previously unresolved bleaching signal in CdSe QDs on timescales faster than 30 fs due to hole cooling. Atomistic semiempirical pseudopotential calculations are used to rationalize the order of magnitude difference in the observed hole dynamics in CdSe and CdSe/CdS/ZnS QDs. This picture advances our understanding of QD excitonics past the prevailing continuum effective mass theories generally used to describe QD electronic structure and dynamics.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Materials Sciences & Engineering Division; National Energy Research Scientific Computing Center (NERSC); European Research Council Horizon 2020
Grant/Contract Number:
AC02-05CH11231; SC0019140; SC0019323
OSTI ID:
2229063
Journal Information:
Communications Physics, Journal Name: Communications Physics Journal Issue: 1 Vol. 6; ISSN 2399-3650
Publisher:
Springer NatureCopyright Statement
Country of Publication:
United States
Language:
English

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