Highly Sensitive Flexible NH3 Sensors Based on Printed Organic Transistors with Fluorinated Conjugated Polymers

Benjamin Nketia-Yawson, A. Ra Jung, Yohan Noh, Gi Seong Ryu, Grace Dansoa Tabi, Kyung Koo Lee, Bongsoo Kim, Yong Young Noh

Research output: Contribution to journalArticlepeer-review

64 Scopus citations

Abstract

Understanding the sensing mechanism in organic chemical sensors is essential for improving the sensing performance such as detection limit, sensitivity, and other response/recovery time, selectivity, and reversibility for real applications. Here, we report a highly sensitive printed ammonia (NH3) gas sensor based on organic thin film transistors (OTFTs) with fluorinated difluorobenzothiadiazole-dithienosilole polymer (PDFDT). These sensors detected NH3 down to 1 ppm with high sensitivity (up to 56%) using bar-coated ultrathin (<4 nm) PDFDT layers without using any receptor additives. The sensing mechanism was confirmed by cyclic voltammetry, hydrogen/fluorine nuclear magnetic resonance, and UV/visible absorption spectroscopy. PDFDT-NH3 interactions comprise hydrogen bonds and electrostatic interactions between the PDFDT polymer backbone and NH3 gas molecules, thus lowering the highest occupied molecular orbital levels, leading to hole trapping in the OTFT sensors. Additionally, density functional theory calculations show that gaseous NH3 molecules are captured via cooperation of fluorine atoms and dithienosilole units in PDFDT. We verified that incorporation of functional groups that interact with a specific gas molecule in a conjugated polymer is a promising strategy for producing high-performance printed OTFT gas sensors.

Original languageEnglish
Pages (from-to)7322-7330
Number of pages9
JournalACS Applied Materials and Interfaces
Volume9
Issue number8
DOIs
StatePublished - 1 Mar 2017

Keywords

  • conjugated polymer
  • fluorination
  • gas sensor
  • organic thin film transistors
  • printing

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