Tuning the Work Function of Printed Polymer Electrodes by Introducing a Fluorinated Polymer To Enhance the Operational Stability in Bottom-Contact Organic Field-Effect Transistors.
Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) is a promising electrode material for organic electronic devices due to its high conductivity, good mechanical flexibility, and feasibility of easy patterning with various printing methods. The work function of PEDOT:PSS needs to be increased for efficient hole injection, and the addition of a fluorine-containing material has been reported to increase the work function of PEDOT:PSS. However, it remains a challenge to print PEDOT:PSS electrodes while simultaneously tuning their work functions. Here, we report work function tunable PEDOT:PSS/Nafion source/drain electrodes formed by electrohydrodynamic printing technique with PEDOT:PSS/Nafion mixture solutions for highly stable bottom-contact organic field-effect transistors (OFETs). The surface properties and work function of the printed electrode can be controlled by varying the Nafion ratio, due to the vertical phase separation of the PEDOT:PSS/Nafion. The PEDOT:PSS/Nafion electrodes exhibit a low hole injection barrier, which leads to efficient charge carrier injection from the electrode to the semiconductor. As a result, pentacene-based OFETs with PEDOT:PSS/Nafion electrodes show increased charge carrier mobilities of 0.39 cm2/(V·s) compared to those of devices with neat PEDOT:PSS electrodes (0.021 cm2/(V·s)). Moreover, the gate-bias stress stability of the OFETs is remarkably improved by employing PEDOT:PSS/Nafion electrodes, as demonstrated by a reduction of the threshold voltage shift from -1.84 V to -0.28 V.
School of Chemical Engineering, Yeungnam University , Gyeongsan, North Gyeongsang 38541, South Korea.
Se Hyun
http://orcid.org/0000-0001-7818-1903
SH
Kim
Department of Chemical Engineering, Pohang University of Science and Technology , Pohang 37673, South Korea.
Jiye
http://orcid.org/0000-0003-3608-5942
J
Kim
Smart I/O Control Device Research Section, Electronics and Telecommunications Research Institute , Daejeon 305-700, Republic of Korea.
Sooji
http://orcid.org/0000-0001-8658-514X
S
Nam
Department of Chemical and Biological Engineering, Hanbat National University , Daejeon 305-719, Republic of Korea.
Hwa Sung
http://orcid.org/0000-0001-9131-810X
HS
Lee
School of Chemical Engineering, Yeungnam University , Gyeongsan, North Gyeongsang 38541, South Korea.
Seung Woo
http://orcid.org/0000-0001-7523-5371
SW
Lee
Department of Energy Engineering, Hanyang University , Seoul 133-791, Republic of Korea.
Jaeyoung
http://orcid.org/0000-0002-5548-8563
J
Jang
Nafion; bottom-contact electrodes; electrohydrodynamic printing; organic field-effect transistors (OFETs); poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS); work function tuning