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

Journal article (2023)

Authors

Patrick J. Brosseau McGill University
J.J. Geuchies ChemE/Opto-electronic Materials - AS
Dipti Jasrasaria University of California
A.J. Houtepen ChemE/Opto-electronic Materials - AS
Eran Rabani University of California, Tel Aviv University, Lawrence Berkeley National Laboratory
Patanjali Kambhampati McGill University
Research Group
ChemE/Opto-electronic Materials (AS) (TU Delft)
Copyright: © 2023 Patrick J. Brosseau, J.J. Geuchies, Dipti Jasrasaria, A.J. Houtepen, Eran Rabani, Patanjali Kambhampati
DOI: https://doi.org/10.1038/s42005-023-01169-1
More Info
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Published Date

2023

Language

English

Faculty

Applied Sciences

Department

ChemE/Chemical Engineering

Research Group

ChemE/Opto-electronic Materials

Abstract

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.