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Title: Comparative electron paramagnetic resonance investigation of reduced graphene oxide and carbon nanotubes with different chemical functionalities for quantum dot attachment

Abstract

Electron paramagnetic resonance (EPR) spectroscopy has been applied to different chemically treated reduced graphene oxide (rGO) and multiwalled carbon nanotubes (CNTs). A narrow EPR signal is visible at g = 2.0029 in both GO and CNT-Oxide from carbon-related dangling bonds. EPR signals became broader and of lower intensity after oxygen-containing functionalities were reduced and partially transformed into thiol groups to obtain thiol-functionalized reduced GO (TrGO) and thiol-functionalized CNT (CNT-SH), respectively. Additionally, EPR investigation of CdSe quantum dot-TrGO hybrid material reveals complete quenching of the TrGO EPR signal due to direct chemical attachment and electronic coupling. Our work confirms that EPR is a suitable tool to detect spin density changes in different functionalized nanocarbon materials and can contribute to improved understanding of electronic coupling effects in nanocarbon-nanoparticle hybrid nano-composites promising for various electronic and optoelectronic applications.

Authors:
; ;  [1];  [2]; ;  [3]
  1. Freiburg Materials Research Center (FMF), University of Freiburg, Stefan-Meier-Str. 21, 79104 Freiburg (Germany)
  2. (IMTEK), University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg (Germany)
  3. Institute of Physical Chemistry, University of Freiburg, Albertstr. 21, 79104 Freiburg (Germany)
Publication Date:
OSTI Identifier:
22261627
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 13; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; CADMIUM SELENIDES; CARBON NANOTUBES; COMPOSITE MATERIALS; ELECTRON SPIN RESONANCE; GRAPHENE; OXIDES; QUANTUM DOTS; THIOLS

Citation Formats

Pham, Chuyen V., Krueger, Michael, E-mail: michael.krueger@fmf.uni-freiburg.de, E-mail: emre.erdem@physchem.uni-freiburg.de, Eck, Michael, Department of Microsystems Engineering, Weber, Stefan, and Erdem, Emre, E-mail: michael.krueger@fmf.uni-freiburg.de, E-mail: emre.erdem@physchem.uni-freiburg.de. Comparative electron paramagnetic resonance investigation of reduced graphene oxide and carbon nanotubes with different chemical functionalities for quantum dot attachment. United States: N. p., 2014. Web. doi:10.1063/1.4870297.
Pham, Chuyen V., Krueger, Michael, E-mail: michael.krueger@fmf.uni-freiburg.de, E-mail: emre.erdem@physchem.uni-freiburg.de, Eck, Michael, Department of Microsystems Engineering, Weber, Stefan, & Erdem, Emre, E-mail: michael.krueger@fmf.uni-freiburg.de, E-mail: emre.erdem@physchem.uni-freiburg.de. Comparative electron paramagnetic resonance investigation of reduced graphene oxide and carbon nanotubes with different chemical functionalities for quantum dot attachment. United States. doi:10.1063/1.4870297.
Pham, Chuyen V., Krueger, Michael, E-mail: michael.krueger@fmf.uni-freiburg.de, E-mail: emre.erdem@physchem.uni-freiburg.de, Eck, Michael, Department of Microsystems Engineering, Weber, Stefan, and Erdem, Emre, E-mail: michael.krueger@fmf.uni-freiburg.de, E-mail: emre.erdem@physchem.uni-freiburg.de. Mon . "Comparative electron paramagnetic resonance investigation of reduced graphene oxide and carbon nanotubes with different chemical functionalities for quantum dot attachment". United States. doi:10.1063/1.4870297.
@article{osti_22261627,
title = {Comparative electron paramagnetic resonance investigation of reduced graphene oxide and carbon nanotubes with different chemical functionalities for quantum dot attachment},
author = {Pham, Chuyen V. and Krueger, Michael, E-mail: michael.krueger@fmf.uni-freiburg.de, E-mail: emre.erdem@physchem.uni-freiburg.de and Eck, Michael and Department of Microsystems Engineering and Weber, Stefan and Erdem, Emre, E-mail: michael.krueger@fmf.uni-freiburg.de, E-mail: emre.erdem@physchem.uni-freiburg.de},
abstractNote = {Electron paramagnetic resonance (EPR) spectroscopy has been applied to different chemically treated reduced graphene oxide (rGO) and multiwalled carbon nanotubes (CNTs). A narrow EPR signal is visible at g = 2.0029 in both GO and CNT-Oxide from carbon-related dangling bonds. EPR signals became broader and of lower intensity after oxygen-containing functionalities were reduced and partially transformed into thiol groups to obtain thiol-functionalized reduced GO (TrGO) and thiol-functionalized CNT (CNT-SH), respectively. Additionally, EPR investigation of CdSe quantum dot-TrGO hybrid material reveals complete quenching of the TrGO EPR signal due to direct chemical attachment and electronic coupling. Our work confirms that EPR is a suitable tool to detect spin density changes in different functionalized nanocarbon materials and can contribute to improved understanding of electronic coupling effects in nanocarbon-nanoparticle hybrid nano-composites promising for various electronic and optoelectronic applications.},
doi = {10.1063/1.4870297},
journal = {Applied Physics Letters},
number = 13,
volume = 104,
place = {United States},
year = {Mon Mar 31 00:00:00 EDT 2014},
month = {Mon Mar 31 00:00:00 EDT 2014}
}
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  • One of the major bottlenecks in fabricating high performance organic field effect transistors (OFETs) is a large interfacial contact barrier between metal electrodes and organic semiconductors (OSCs) which makes the charge injection inefficient. Recently, reduced graphene oxide (RGO) has been suggested as an alternative electrode material for OFETs. RGO has tunable electronic properties and its conductivity can be varied by several orders of magnitude by varying the carbon sp{sup 2} fraction. However, whether the sp{sup 2} fraction of RGO in the electrode affects the performance of the fabricated OFETs is yet to be investigated. In this study, we demonstrate thatmore » the performance of OFETs with pentacene as OSC and RGO as electrode can be continuously improved by increasing the carbon sp{sup 2} fraction of RGO. When compared to control palladium electrodes, the mobility of the OFETs shows an improvement of ∼200% for 61% sp{sup 2} fraction RGO, which further improves to ∼500% for 80% RGO electrode. Similar improvements were also observed in current on-off ratio, on-current, and transconductance. Our study suggests that, in addition to π-π interaction at RGO/pentacene interface, the tunable electronic properties of RGO electrode have a significant role in OFETs performance.« less