Highly Sensitive Flexible NH3Sensors Based on Printed Organic Transistors with Fluorinated Conjugated Polymers.
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 NH3down 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-NH3interactions comprise hydrogen bonds and electrostatic interactions between the PDFDT polymer backbone and NH3gas 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 NH3molecules 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.
Benjamin
B
Nketia-Yawson
Department of Science Education, Ewha Womans University , 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Republic of Korea.
A-Ra
AR
Jung
Department of Chemistry, Kunsan National University , 558 Daehak-ro, Gunsan, Jeonbuk 54150, Republic of Korea.
Yohan
Y
Noh
Gi-Seong
GS
Ryu
Grace Dansoa
GD
Tabi
Department of Chemistry, Kunsan National University , 558 Daehak-ro, Gunsan, Jeonbuk 54150, Republic of Korea.
Kyung-Koo
KK
Lee
Department of Science Education, Ewha Womans University , 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 03760, Republic of Korea.
BongSoo
B
Kim
Yong-Young
http://orcid.org/0000-0001-7222-2401
YY
Noh
conjugated polymer; fluorination; gas sensor; organic thin film transistors; printing