Nitrogen plasma surface modification of poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate) films to enhance the piezoresistive pressure-sensing properties

Jer Chyi Wang*, Rajat Subhra Karmakar, Yu Jen Lu, Ming Chung Wu, Kuo Chen Wei

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

16 Scopus citations

Abstract

A conductive polymeric film, poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS), is surface-modified by nitrogen plasma in order to enhance its piezoresistive characteristics. With an optimized 3 min nitrogen plasma surface modification, the piezoresistive sensitivity and response were significantly enhanced. Hall measurements and temperature-dependent conductance measurements are carried out to determine the electron-hopping behavior of nitrogen-plasma-modified PEDOT:PSS films, suppressing the horizontal carrier conducting pathway in the PEDOT:PSS piezoresistive pressure sensors. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy are applied to observe the PEDOT:PSS film surface after being modified with nitrogen plasma. The presence of sulfamate (SO3-NH2) and thiocyanate (S-C?N) groups indicates a breaking of the electrostatic bonding between PEDOT and PSS and a modification of the conductive PEDOT conjugated chain. At the film surface, the formation of thiocyanate groups of PEDOT oligomers without the electrostatic bonding of PSS makes the PEDOT:PSS more hydrophobic, changing the surface characteristics of the PEDOT:PSS film. The newly formed less-conductive film surface alters the piezoresistance of PEDOT:PSS pressure sensors, implying their potential applications for future high-performance tactile sensing.

Original languageEnglish
Pages (from-to)25977-25984
Number of pages8
JournalJournal of Physical Chemistry C
Volume120
Issue number45
DOIs
StatePublished - 17 11 2016

Bibliographical note

Publisher Copyright:
© 2016 American Chemical Society.

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