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Title: Solvent- and Wavelength-Dependent Photoluminescence Relaxation Dynamics of Carbon Nanotube sp 3 Defect States

Abstract

Photoluminescent sp 3 defect states introduced to single wall carbon nanotubes (SWCNTs) through low-level covalent functionalization create new photophysical behaviors and functionality as a result of defect sites acting as exciton traps. Evaluation of relaxation dynamics in varying dielectric environments can aid in advancing a more complete description of defect-state relaxation pathways and electronic structure. For this study, we exploit helical wrapping polymers as a route to suspending (6,5) SWCNTs covalently functionalized with 4-methoxybenzene in solvent systems including H 2O, D 2O, methanol, dimethylformamide, tetrahydrofuran, and toluene, spanning a range of dielectric constants from 80 to 3. Defect-state photoluminescence decays were measured as a function of emission wavelength and solvent environment. Emission decays are biexponential, with short lifetime components on the order of 65 ps and long components ranging from around 100 to 350 ps. Both short and long decay components increase as emission wavelength increases, while only the long lifetime component shows a solvent dependence. We demonstrate that the wavelength dependence is a consequence of thermal detrapping of defect-state excitons to produce mobile E 11 excitons, providing an important mechanism for loss of defect-state population. Deeper trap states (i.e., those emitting at longer wavelengths) result in a decreased ratemore » for thermal loss. The solvent-independent behavior of the short lifetime component is consistent with its assignment as the characteristic time for redistribution of exciton population between bright and dark defect states. Furthermore, the solvent dependence of the long lifetime component is shown to be consistent with relaxation via an electronic to vibrational energy transfer mechanism, in which energy is resonantly lost to solvent vibrations in a complementary mechanism to multiphonon decay processes.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2];  [2]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Duke Univ., Durham, NC (United States). Dept. of Chemistry and French Family Science Center
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); North Dakota State Univ., Fargo, ND (United States). Dept. of Chemistry and Biochemistry
  4. North Dakota State Univ., Fargo, ND (United States). Dept. of Chemistry and Biochemistry
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
1461401
Report Number(s):
LA-UR-18-23574
Journal ID: ISSN 1936-0851
Grant/Contract Number:  
AC52-06NA25396; SC0001517
Resource Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 12; Journal Issue: 8; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; Material Science; electronic-to-vibrational energy transfer; exciton; photoluminescence decay; relaxation dynamics; single wall carbon nanotubes; sp3 defects; thermal detrapping

Citation Formats

He, Xiaowei, Velizhanin, Kirill A., Bullard, George, Bai, Yusong, Olivier, Jean-Hubert, Hartmann, Nicolai F., Gifford, Brendan J., Kilina, Svetlana, Tretiak, Sergei, Htoon, Han, Therien, Michael J., and Doorn, Stephen K. Solvent- and Wavelength-Dependent Photoluminescence Relaxation Dynamics of Carbon Nanotube sp3 Defect States. United States: N. p., 2018. Web. doi:10.1021/acsnano.8b02909.
He, Xiaowei, Velizhanin, Kirill A., Bullard, George, Bai, Yusong, Olivier, Jean-Hubert, Hartmann, Nicolai F., Gifford, Brendan J., Kilina, Svetlana, Tretiak, Sergei, Htoon, Han, Therien, Michael J., & Doorn, Stephen K. Solvent- and Wavelength-Dependent Photoluminescence Relaxation Dynamics of Carbon Nanotube sp3 Defect States. United States. doi:10.1021/acsnano.8b02909.
He, Xiaowei, Velizhanin, Kirill A., Bullard, George, Bai, Yusong, Olivier, Jean-Hubert, Hartmann, Nicolai F., Gifford, Brendan J., Kilina, Svetlana, Tretiak, Sergei, Htoon, Han, Therien, Michael J., and Doorn, Stephen K. Wed . "Solvent- and Wavelength-Dependent Photoluminescence Relaxation Dynamics of Carbon Nanotube sp3 Defect States". United States. doi:10.1021/acsnano.8b02909. https://www.osti.gov/servlets/purl/1461401.
@article{osti_1461401,
title = {Solvent- and Wavelength-Dependent Photoluminescence Relaxation Dynamics of Carbon Nanotube sp3 Defect States},
author = {He, Xiaowei and Velizhanin, Kirill A. and Bullard, George and Bai, Yusong and Olivier, Jean-Hubert and Hartmann, Nicolai F. and Gifford, Brendan J. and Kilina, Svetlana and Tretiak, Sergei and Htoon, Han and Therien, Michael J. and Doorn, Stephen K.},
abstractNote = {Photoluminescent sp3 defect states introduced to single wall carbon nanotubes (SWCNTs) through low-level covalent functionalization create new photophysical behaviors and functionality as a result of defect sites acting as exciton traps. Evaluation of relaxation dynamics in varying dielectric environments can aid in advancing a more complete description of defect-state relaxation pathways and electronic structure. For this study, we exploit helical wrapping polymers as a route to suspending (6,5) SWCNTs covalently functionalized with 4-methoxybenzene in solvent systems including H2O, D2O, methanol, dimethylformamide, tetrahydrofuran, and toluene, spanning a range of dielectric constants from 80 to 3. Defect-state photoluminescence decays were measured as a function of emission wavelength and solvent environment. Emission decays are biexponential, with short lifetime components on the order of 65 ps and long components ranging from around 100 to 350 ps. Both short and long decay components increase as emission wavelength increases, while only the long lifetime component shows a solvent dependence. We demonstrate that the wavelength dependence is a consequence of thermal detrapping of defect-state excitons to produce mobile E11 excitons, providing an important mechanism for loss of defect-state population. Deeper trap states (i.e., those emitting at longer wavelengths) result in a decreased rate for thermal loss. The solvent-independent behavior of the short lifetime component is consistent with its assignment as the characteristic time for redistribution of exciton population between bright and dark defect states. Furthermore, the solvent dependence of the long lifetime component is shown to be consistent with relaxation via an electronic to vibrational energy transfer mechanism, in which energy is resonantly lost to solvent vibrations in a complementary mechanism to multiphonon decay processes.},
doi = {10.1021/acsnano.8b02909},
journal = {ACS Nano},
number = 8,
volume = 12,
place = {United States},
year = {2018},
month = {7}
}

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