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Title: Direct Observation of Photoexcited Hole Localization in CdSe Nanorods

Abstract

Quantum-confined 1D semiconductor nanostructures are being investigated for hydrogen generation photocatalysts. In the photoreaction, after fast electron transfer, holes that remain in the nanostructure play an important role in the total quantum yield of hydrogen production. Unfortunately, knowledge of hole dynamics is limited due to lack of convenient spectroscopic signatures. Here, we directly probe hole localization dynamics within CdSe nanorods (NRs) by combining transient absorption (TA) and time-resolved terahertz (TRTS) spectroscopy. We show that when methylene blue is used as an electron acceptor, the resulting electron transfer occurs with a time constant of 3.5 ± 0.1 ps and leaves behind a delocalized hole. However, the hole quickly localizes in the Coulomb potential well generated by the reduced electron acceptor near the NR surface with time constant of 11.7 ± 0.2 ps. Our theoretical investigation suggests that the hole becomes confined to a ~±0.8 nm region near the reduced electron acceptor and the activation energy to detrap the hole from the potential well can be as large as 235 meV.

Authors:
 [1];  [2];  [3];  [3];  [2];  [1]
  1. Chemical and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
  2. The Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
  3. Center for Computational Material Science, Naval Research Laboratory, Washington, DC 20375, United States
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Advanced Solar Photophysics (CASP)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; US Department of the Navy, Office of Naval Research (ONR)
OSTI Identifier:
1338626
Alternate Identifier(s):
OSTI ID: 1388206
Grant/Contract Number:  
AC36-08GO28308; FG02-12ER16347; AC52-06NA25396
Resource Type:
Published Article
Journal Name:
ACS Energy Letters
Additional Journal Information:
Journal Name: ACS Energy Letters Journal Volume: 1 Journal Issue: 1; Journal ID: ISSN 2380-8195
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; solar (photovoltaic); solar (fuels); solid state lighting; bio-inspired; electrodes - solar; defects; charge transport; materials and chemistry by design; optics; synthesis (novel materials); synthesis (scalable processing)

Citation Formats

Yang, Ye, Wu, Kaifeng, Shabaev, Andrew, Efros, Alexander L., Lian, Tianquan, and Beard, Matthew C. Direct Observation of Photoexcited Hole Localization in CdSe Nanorods. United States: N. p., 2016. Web. doi:10.1021/acsenergylett.6b00036.
Yang, Ye, Wu, Kaifeng, Shabaev, Andrew, Efros, Alexander L., Lian, Tianquan, & Beard, Matthew C. Direct Observation of Photoexcited Hole Localization in CdSe Nanorods. United States. doi:10.1021/acsenergylett.6b00036.
Yang, Ye, Wu, Kaifeng, Shabaev, Andrew, Efros, Alexander L., Lian, Tianquan, and Beard, Matthew C. Fri . "Direct Observation of Photoexcited Hole Localization in CdSe Nanorods". United States. doi:10.1021/acsenergylett.6b00036.
@article{osti_1338626,
title = {Direct Observation of Photoexcited Hole Localization in CdSe Nanorods},
author = {Yang, Ye and Wu, Kaifeng and Shabaev, Andrew and Efros, Alexander L. and Lian, Tianquan and Beard, Matthew C.},
abstractNote = {Quantum-confined 1D semiconductor nanostructures are being investigated for hydrogen generation photocatalysts. In the photoreaction, after fast electron transfer, holes that remain in the nanostructure play an important role in the total quantum yield of hydrogen production. Unfortunately, knowledge of hole dynamics is limited due to lack of convenient spectroscopic signatures. Here, we directly probe hole localization dynamics within CdSe nanorods (NRs) by combining transient absorption (TA) and time-resolved terahertz (TRTS) spectroscopy. We show that when methylene blue is used as an electron acceptor, the resulting electron transfer occurs with a time constant of 3.5 ± 0.1 ps and leaves behind a delocalized hole. However, the hole quickly localizes in the Coulomb potential well generated by the reduced electron acceptor near the NR surface with time constant of 11.7 ± 0.2 ps. Our theoretical investigation suggests that the hole becomes confined to a ~±0.8 nm region near the reduced electron acceptor and the activation energy to detrap the hole from the potential well can be as large as 235 meV.},
doi = {10.1021/acsenergylett.6b00036},
journal = {ACS Energy Letters},
number = 1,
volume = 1,
place = {United States},
year = {2016},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1021/acsenergylett.6b00036

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Cited by: 3 works
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