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

Rawad K. Hallani, Bryan D. Paulsen, Anthony J. Petty, Rajendar Sheelamanthula, Maximilian Moser, Karl J. 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

80 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)
Pages (from-to)11007-11018
Number of pages12
JournalJournal of the American Chemical Society
Issue number29
StatePublished - Jul 28 2021
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry


Dive into the research topics of 'Regiochemistry-Driven Organic Electrochemical Transistor Performance Enhancement in Ethylene Glycol-Functionalized Polythiophenes'. Together they form a unique fingerprint.

Cite this