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Title: Direct Evidence of Exciton–Exciton Annihilation in Single-Crystalline Organic Metal Halide Nanotube Assemblies

Abstract

Excitons in low-dimensional organic–inorganic metal halide hybrid structures are commonly thought to undergo rapid self-trapping following creation due to strong quantum confinement and exciton–phonon interaction. Here we report an experimental study probing the dynamics of these self-trapped excitons in the single-crystalline bulk assemblies of 1D organic metal halide nanotubes, (C 6H 13N 4) 3Pb 2Br 7. Through time-resolved photoluminescence (PL) measurements at different excitation intensities, we observed a marked variation in the PL decay behavior that is manifested by an accelerated decay rate with increasing excitation fluence. Our results offer direct evidence of the occurrence of an exciton–exciton annihilation process, a nonlinear relaxation phenomenon that takes place only when some of the self-trapped excitons become mobile and can approach either each other or those trapped excitons. As a result, we further identify a fast and dominant PL decay component with a lifetime of ~2 ns with a nearly invariant relative area for all acquired PL kinetics, suggesting that this rapid relaxation process is intrinsic.

Authors:
ORCiD logo [1];  [2]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. FAMU-FSU College of Engineering, Tallahassee, FL (United States)
  3. FAMU-FSU College of Engineering, Tallahassee, FL (United States); Florida State Univ., Tallahassee, FL (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1436038
Grant/Contract Number:  
[AC05-00OR22725]
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry Letters
Additional Journal Information:
[ Journal Volume: 9; Journal Issue: 9]; Journal ID: ISSN 1948-7185
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Ma, Ying -Zhong, Lin, Haoran, Du, Mao -Hua, Doughty, Benjamin L., and Ma, Biwu. Direct Evidence of Exciton–Exciton Annihilation in Single-Crystalline Organic Metal Halide Nanotube Assemblies. United States: N. p., 2018. Web. doi:10.1021/acs.jpclett.8b00761.
Ma, Ying -Zhong, Lin, Haoran, Du, Mao -Hua, Doughty, Benjamin L., & Ma, Biwu. Direct Evidence of Exciton–Exciton Annihilation in Single-Crystalline Organic Metal Halide Nanotube Assemblies. United States. doi:10.1021/acs.jpclett.8b00761.
Ma, Ying -Zhong, Lin, Haoran, Du, Mao -Hua, Doughty, Benjamin L., and Ma, Biwu. Wed . "Direct Evidence of Exciton–Exciton Annihilation in Single-Crystalline Organic Metal Halide Nanotube Assemblies". United States. doi:10.1021/acs.jpclett.8b00761. https://www.osti.gov/servlets/purl/1436038.
@article{osti_1436038,
title = {Direct Evidence of Exciton–Exciton Annihilation in Single-Crystalline Organic Metal Halide Nanotube Assemblies},
author = {Ma, Ying -Zhong and Lin, Haoran and Du, Mao -Hua and Doughty, Benjamin L. and Ma, Biwu},
abstractNote = {Excitons in low-dimensional organic–inorganic metal halide hybrid structures are commonly thought to undergo rapid self-trapping following creation due to strong quantum confinement and exciton–phonon interaction. Here we report an experimental study probing the dynamics of these self-trapped excitons in the single-crystalline bulk assemblies of 1D organic metal halide nanotubes, (C6H13N4)3Pb2Br7. Through time-resolved photoluminescence (PL) measurements at different excitation intensities, we observed a marked variation in the PL decay behavior that is manifested by an accelerated decay rate with increasing excitation fluence. Our results offer direct evidence of the occurrence of an exciton–exciton annihilation process, a nonlinear relaxation phenomenon that takes place only when some of the self-trapped excitons become mobile and can approach either each other or those trapped excitons. As a result, we further identify a fast and dominant PL decay component with a lifetime of ~2 ns with a nearly invariant relative area for all acquired PL kinetics, suggesting that this rapid relaxation process is intrinsic.},
doi = {10.1021/acs.jpclett.8b00761},
journal = {Journal of Physical Chemistry Letters},
number = [9],
volume = [9],
place = {United States},
year = {2018},
month = {4}
}

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Figures / Tables:

Figure 1 Figure 1: (a) View of the structure of (C6H13N4)3Pb2Br7 nanotube array, where red, green, blue, and gray denote lead, bromine, nitrogen, and carbon atoms, respectively. Purple polyhedra depict PbBr6 octahedra and Pb2Br9 dimers, and hydrogen atoms are hidden for clarity. (b) Schematic energy level diagram of a nanotube involving exciton−excitonmore » annihilation and exciton self-trapping and detrapping between the lowest-lying free exciton state (FES1) and self-trapped exciton state (STES). GS and FESn denote the ground and a high-lying free exciton state, respectively.« less

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