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Engineering work function of graphene oxide from p to n type using a low power atmospheric pressure plasma jet

Dey, Avishek; Ghosh, Paheli; Bowen, James; Braithwaite, N St.J and Krishnamurthy, Satheesh (2020). Engineering work function of graphene oxide from p to n type using a low power atmospheric pressure plasma jet. Physical Chemistry Chemical Physics (Early Access).

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DOI (Digital Object Identifier) Link: https://doi.org/10.1039/C9CP06174F
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Abstract

In this work, we demonstrate doping graphene oxide (GO) films using a low power atmospheric pressure plasma jet (APPJ) with subsequent tuning of the work function. The surface potential of the plasma functionalized GO films could be tuned by 120 ± 10 mV by varying plasma parameters. X-ray spectroscopy used to probe these changes in electronic structure of systematically functionalized GO films by plasma. Detailed investigation using X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure spectroscopy revealed the reactive nitrogen species in the plasma induce finite changes in the surface chemistry of the GO films, introducing additional density of states near the top of the valence band edge. Nitrogen introduced by the atmospheric pressure plasma is predominantly in a graphitic configuration with a varying concentration of pyridinic nitrogen. Additionally, evidence of gradual de-epoxidation of these GO films with increasing plasma exposure was also observed. We attribute this variation in work function values to the configuration of nitrogen in the graphitic structure as revealed by X-ray spectroscopy. With pyridinic nitrogen the electronic states of GO became electron deficient, inducing a p-type doping whereas increase in graphitic nitrogen increased the electron density of GO leading to an n-type doping effect. Nitrogen doping was also found to decrease the resistivity from 138 MΩsq-1 to 4-1MΩsq. These findings are extremely useful in fabricating hetrojunctions like sensor, optoelectronic devices where band structure alignment is key to device performance when GO is used as a charge transport layer. This technique can be extended to other known 2D systems.

Item Type: Journal Item
Copyright Holders: 2020 RSC
ISSN: 1463-9076
Project Funding Details:
Funded Project NameProject IDFunding Body
Recycling LIBsNot SetRoyal Academy of Engineering
Keywords: graphene oxide; doping; work function; plasma jet; flexible electronics; functionalization; surface coating
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Engineering and Innovation
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Research Group: Smart Materials
Item ID: 69118
Depositing User: Satheesh Krishnamurthy
Date Deposited: 24 Jan 2020 09:43
Last Modified: 29 Mar 2020 13:06
URI: http://oro.open.ac.uk/id/eprint/69118
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