Precise Side-Chain Engineering of Thienylenevinylene-Benzotriazole-Based Conjugated Polymers with Coplanar Backbone for Organic Field Effect Transistors and CMOS-like Inverters

Min-Hye Lee; Juhwan Kim; Minji Kang; Jihong Kim; Boseok Kang; Hansu Hwang; Kilwon Cho; Dong-Yu Kim

doi:10.1021/acsami.6b14701

Precise Side-Chain Engineering of Thienylenevinylene-Benzotriazole-Based Conjugated Polymers with Coplanar Backbone for Organic Field Effect Transistors and CMOS-like Inverters

ACS Appl Mater Interfaces. 2017 Jan 25;9(3):2758-2766. doi: 10.1021/acsami.6b14701. Epub 2017 Jan 9.

Authors

Min-Hye Lee¹, Juhwan Kim², Minji Kang¹, Jihong Kim¹, Boseok Kang³, Hansu Hwang¹, Kilwon Cho³, Dong-Yu Kim¹

Affiliations

¹ School of Materials Science and Engineering, Gwangju Institute of Science and Technology , 123, Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea.
² Department of Chemical Engineering and Materials Science, University of California, Irvine , Irvine, California 92697, United States.
³ Department of Chemical Engineering and Center for Advanced Soft Electronics, Pohang University of Science and Technology , 77, Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Republic of Korea.

PMID: 28004581
DOI: 10.1021/acsami.6b14701

Abstract

Two donor-acceptor (D-A) alternating conjugated polymers based on thienylenevinylene-benzotriazole (TV-BTz), PTV6B with a linear side chain and PTVEhB with a branched side chain, were synthesized and characterized for organic field effect transistors (OFETs) and complementary metal-oxide-semiconductor (CMOS)-like inverters. According to density functional theory (DFT), polymers based on TV-BTz exhibit a coplanar and rigid structure with no significant twists, which could cause to an increase in charge-carrier mobility in OFETs. Alternating alkyl side chains of the polymers impacted neither the band gap nor the energy level. However, it significantly affected the morphology and crystallinity when the polymer films were thermally annealed. To investigate the effect of thermal annealing on the morphology and crystallinity, we characterized the polymer films using atomic force microscopy (AFM) and 2D-grazing incidence X-ray diffraction (2D-GIWAXD). Fibrillary morphologies with larger domains and increased crystallinity were observed in the polymer films after thermal annealing. These polymers exhibited improved charge-carrier mobilities in annealed films at 200 °C and demonstrated optimal OFET device performance with p-type transport characteristics with charge-carrier mobilities of 1.51 cm²/(V s) (PTV6B) and 2.58 cm²/(V s) (PTVEhB). Furthermore, CMOS-like inorganic (ZnO)-organic (PTVEhB) hybrid bilayer inverter showed that the inverting voltage (V_inv) was positioned near the ideal switching point at half (1/2) of supplied voltage (V_DD) due to fairly balanced p- and n-channels.

Keywords: CMOS-like inverter; conjugated polymer; coplanar backbone; donor−acceptor configuration; organic field effect transistor; side-chain engineering.