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Title: Distinguishing Electron and Hole Dynamics in Functionalized CdSe/CdS Core/Shell Quantum Dots Using Complementary Ultrafast Spectroscopies and Kinetic Modeling

Abstract

The evolution of excitation energy and photogenerated charges in semiconductor quantum dots (QDs) functionalized with molecular acceptors can be probed on ultrafast time scales using techniques such as transient absorption (TA) spectroscopy. However, historical interpretations that the 1S(e)-1S3/2(h) transition in Cd-chalcogenide QDs is fully attributable to electrons may be misleading, and multiexponential models used to fit TA kinetics do not correspond directly to specific photophysical processes. Here, we present visible-wavelength and mid-IR TA and time-resolved photoluminescence measurements to inform a comprehensive kinetic model of the photoexcited CdSe/CdS core/shell QDs functionalized with passivating oleic acid (OA), hole-accepting ferrocene, or electron-accepting naphthalene bisimide (NBI). We show that ~30% of the 1S signal and 72% of the IR signal can originate from holes in well-passivated core/shell QDs. We also demonstrate evidence of electron trapping in OA-capped core/shell QDs, with additional electron transfer and hole trapping in the QDs functionalized with NBI. Electron (hole) trapping and detrapping occur in 450 ± 100 ps (430 ± 70 ps) and 340 ± 100 ps (1.1 ± 0.4 ns) respectively, while the time constant for electron transfer to NBI is ~1.8 ns. The comprehensive picture of photophysical processes provided by the complementary ultrafast techniques and kinetic modelingmore » can accelerate both the fundamental science and application development of nanostructured and molecular systems.« less

Authors:
ORCiD logo [1];  [2];  [2]; ORCiD logo [3];  [2];  [2]; ORCiD logo [1]
  1. Drexel Univ., Philadelphia, PA (United States)
  2. Univ. of Pennsylvania, Philadelphia, PA (United States)
  3. Argonne National Lab. (ANL), Lemont, IL (United States). Center for Nanoscale Materials
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials
Sponsoring Org.:
National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1760171
Grant/Contract Number:  
AC02-06CH11357; CHE-1708991; CHE-1709827; DGE-1321851
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 125; 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; Quantum dots; Charge transfer; Kinetic modeling; Kinetics; Probes

Citation Formats

Taheri, Mohammad M., Elbert, Katherine C., Yang, Shengsong, Diroll, Benjamin T., Park, Jungmi, Murray, Christopher B., and Baxter, Jason B. Distinguishing Electron and Hole Dynamics in Functionalized CdSe/CdS Core/Shell Quantum Dots Using Complementary Ultrafast Spectroscopies and Kinetic Modeling. United States: N. p., 2020. Web. doi:10.1021/acs.jpcc.0c07037.
Taheri, Mohammad M., Elbert, Katherine C., Yang, Shengsong, Diroll, Benjamin T., Park, Jungmi, Murray, Christopher B., & Baxter, Jason B. Distinguishing Electron and Hole Dynamics in Functionalized CdSe/CdS Core/Shell Quantum Dots Using Complementary Ultrafast Spectroscopies and Kinetic Modeling. United States. https://doi.org/10.1021/acs.jpcc.0c07037
Taheri, Mohammad M., Elbert, Katherine C., Yang, Shengsong, Diroll, Benjamin T., Park, Jungmi, Murray, Christopher B., and Baxter, Jason B. 2020. "Distinguishing Electron and Hole Dynamics in Functionalized CdSe/CdS Core/Shell Quantum Dots Using Complementary Ultrafast Spectroscopies and Kinetic Modeling". United States. https://doi.org/10.1021/acs.jpcc.0c07037. https://www.osti.gov/servlets/purl/1760171.
@article{osti_1760171,
title = {Distinguishing Electron and Hole Dynamics in Functionalized CdSe/CdS Core/Shell Quantum Dots Using Complementary Ultrafast Spectroscopies and Kinetic Modeling},
author = {Taheri, Mohammad M. and Elbert, Katherine C. and Yang, Shengsong and Diroll, Benjamin T. and Park, Jungmi and Murray, Christopher B. and Baxter, Jason B.},
abstractNote = {The evolution of excitation energy and photogenerated charges in semiconductor quantum dots (QDs) functionalized with molecular acceptors can be probed on ultrafast time scales using techniques such as transient absorption (TA) spectroscopy. However, historical interpretations that the 1S(e)-1S3/2(h) transition in Cd-chalcogenide QDs is fully attributable to electrons may be misleading, and multiexponential models used to fit TA kinetics do not correspond directly to specific photophysical processes. Here, we present visible-wavelength and mid-IR TA and time-resolved photoluminescence measurements to inform a comprehensive kinetic model of the photoexcited CdSe/CdS core/shell QDs functionalized with passivating oleic acid (OA), hole-accepting ferrocene, or electron-accepting naphthalene bisimide (NBI). We show that ~30% of the 1S signal and 72% of the IR signal can originate from holes in well-passivated core/shell QDs. We also demonstrate evidence of electron trapping in OA-capped core/shell QDs, with additional electron transfer and hole trapping in the QDs functionalized with NBI. Electron (hole) trapping and detrapping occur in 450 ± 100 ps (430 ± 70 ps) and 340 ± 100 ps (1.1 ± 0.4 ns) respectively, while the time constant for electron transfer to NBI is ~1.8 ns. The comprehensive picture of photophysical processes provided by the complementary ultrafast techniques and kinetic modeling can accelerate both the fundamental science and application development of nanostructured and molecular systems.},
doi = {10.1021/acs.jpcc.0c07037},
url = {https://www.osti.gov/biblio/1760171}, journal = {Journal of Physical Chemistry. C},
issn = {1932-7447},
number = 1,
volume = 125,
place = {United States},
year = {Thu Dec 31 00:00:00 EST 2020},
month = {Thu Dec 31 00:00:00 EST 2020}
}

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