High performance of low band gap polymer-based ambipolar transistor using single-layer graphene electrodes.
Bottom-contact bottom-gate organic field-effect transistors (OFETs) are fabricated using a low band gap pDTTDPP-DT polymer as a channel material and single-layer graphene (SLG) or Au source/drain electrodes. The SLG-based ambipolar OFETs significantly outperform the Au-based ambipolar OFETs, and thermal annealing effectively improves the carrier mobilities of the pDTTDPP-DT films. The difference is attributed to the following facts: (i) the thermally annealed pDTTDPP-DT chains on the SLG assume more crystalline features with an edge-on orientation as compared to the polymer chains on the Au, (ii) the morphological features of the thermally annealed pDTTDPP-DT films on the SLG electrodes are closer to the features of those on the gate dielectric layer, and (iii) the SLG electrode provides a flatter, more hydrophobic surface that is favorable for the polymer crystallization than the Au. In addition, the preferred carrier transport in each electrode-based OFET is associated with the HOMO/LUMO alignment relative to the Fermi level of the employed electrode. All of these experimental results consistently explain why the carrier mobilities of the SLG-based OFET are more than 10 times higher than those of the Au-based OTFT. This work demonstrates the strong dependence of ambipolar carrier transport on the source/drain electrode and annealing temperature.
†Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Hwarangno14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea.|‡Department of Chemistry, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea.
Jong Yong
JY
Choi
§SKKU Advanced Institute of Nanotechnology (SAINT), School of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan, Suwon-si, Gyeonggi-do 440-746, Republic of Korea.
Woonggi
W
Kang
∥Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Gyeong-buk 790-784, Republic of Korea.
Boseok
B
Kang
⊥Department of Physics, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 121-742, Republic of Korea.
Wonsuk
W
Cha
†Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Hwarangno14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea.
Seon Kyoung
SK
Son
†Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Hwarangno14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea.
Youngwoon
Y
Yoon
⊥Department of Physics, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 121-742, Republic of Korea.
Hyunjung
H
Kim
‡Department of Chemistry, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea.
Youngjong
Y
Kang
†Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Hwarangno14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea.|#Green School (School of Energy and Environment), Korea University, 1, Anam-dong 5-ga, Seongbuk-gu, Seoul 136-701, Republic of Korea.
Min Jae
MJ
Ko
†Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Hwarangno14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea.
Hae Jung
HJ
Son
∥Department of Chemical Engineering, Pohang University of Science and Technology, Pohang, Gyeong-buk 790-784, Republic of Korea.
Kilwon
K
Cho
§SKKU Advanced Institute of Nanotechnology (SAINT), School of Chemical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Jangan, Suwon-si, Gyeonggi-do 440-746, Republic of Korea.
Jeong Ho
JH
Cho
†Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Hwarangno14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea.|○Department of Science Education, Ewha Womans University, Seoul 120-750, Republic of Korea.
BongSoo
B
Kim
ambipolar organic field-effect transistor; film crystallinity; high carrier mobility; low band gap polymer; single layer graphene electrode