Regiochemistry-Driven Organic Electrochemical Transistor Performance Enhancement in Ethylene Glycol-Functionalized Polythiophenes

Rawad Hallani, Bryan D. Paulsen, Anthony J. Petty, Rajendar Sheelamanthula, Maximilian Moser, Karl Thorley, Wonil Sohn, Reem B. Rashid, Achilleas Savva, Stefania Moro, Joseph P. Parker, Oscar Drury, Maryam Alsufyani, Marios Neophytou, Jan Kosco, Sahika Inal, Giovanni Costantini, Jonathan Rivnay, Iain McCulloch

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


Novel p-type semiconducting polymers that can facilitate ion penetration, and operate in accumulation mode are much desired in bioelectronics. Glycol side chains have proven to be an efficient method to increase bulk electrochemical doping and optimize aqueous swelling. One early polymer which exemplifies these design approaches was p(g2T-TT), employing a bithiophene-co-thienothiophene backbone with glycol side chains in the 3,3' positions of the bithiophene repeat unit. In this paper, the analogous regioisomeric polymer, namely pgBTTT, was synthesized by relocating the glycol side chains position on the bithiophene unit of p(g2T-TT) from the 3,3' to the 4,4' positions and compared with the original p(g2T-TT). By changing the regio-positioning of the side chains, the planarizing effects of the S-O interactions were redistributed along the backbone, and the influence on the polymer's microstructure organization was investigated using grazing-incidence wide-angle X-ray scattering (GIWAXS) measurements. The newly designed pgBTTT exhibited lower backbone disorder, closer π-stacking, and higher scattering intensity in both the in-plane and out-of-plane GIWAXS measurements. The effect of the improved planarity of pgBTTT manifested as higher hole mobility (μ) of 3.44 ± 0.13 cm2 V-1 s-1. Scanning tunneling microscopy (STM) was in agreement with the GIWAXS measurements and demonstrated, for the first time, that glycol side chains can also facilitate intermolecular interdigitation analogous to that of pBTTT. Electrochemical quartz crystal microbalance with dissipation of energy (eQCM-D) measurements revealed that pgBTTT maintains a more rigid structure than p(g2T-TT) during doping, minimizing molecular packing disruption and maintaining higher hole mobility in operation mode.
Original languageEnglish (US)
JournalJournal of the American Chemical Society
StatePublished - Jun 30 2021

Bibliographical note

KAUST Repository Item: Exported on 2021-07-16
Acknowledged KAUST grant number(s): OSR-2018-CRG/CCF-3079, OSR-2018-CRG7-3749, OSR-2019-CRG8-4086
Acknowledgements: The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST), including Office of Sponsored Research (OSR) awards no. OSR-2018-CRG/CCF-3079, OSR-2019-CRG8-4086 and OSR-2018-CRG7-3749. We acknowledge funding from ERC Synergy Grant SC2 (610115), the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 952911, project BOOSTER and grant agreement no. 862474, project RoLAFLEX, as well as EPSRC Project EP/T026219/1. B.D.P. and J.R. gratefully acknowledge support from the National Science Foundation grant no. NSF DMR-1751308. W.S. gratefully acknowledges support from the Northwestern University Office of Undergraduate Research. Special thanks to Joseph Strzalka and Qingteng Zhang for beamline assistance. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This work utilized Keck-II facility of Northwestern University’s NUANCE Center and Northwestern University Micro/Nano Fabrication Facility (NUFAB), which are both partially supported by Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205), the Materials Research Science and Engineering Center (NSF DMR1720139), the State of Illinois, and Northwestern University. Additionally, the Keck-II facility is partially supported by the
International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. S.M. acknowledges funding though an EU Chancellor’s Scholarship by the University of Warwick. J.P.P. acknowledges support by the Biotechnology and Biological Sciences Research Council (BBSRC) and University of Warwick funded Midlands Integrative Biosciences Training Partnership (MIBTP) (grant number BB/M01116X/1).

ASJC Scopus subject areas

  • Biochemistry
  • Colloid and Surface Chemistry
  • Chemistry(all)
  • Catalysis


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