The Role of Long-Alkyl-Group Spacers in Glycolated Copolymers for High-Performance Organic Electrochemical Transistors

Ellasia Tan, Jingwan Kim, Katherine Stewart, Charalampos Pitsalidis, Sooncheol Kwon, Nicholas Siemons, Jehan Kim, Yifei Jiang, Jarvist M. Frost, Drew Pearce, James E. Tyrrell, Jenny Nelson, Roisin M. Owens, Yun Hi Kim, Ji Seon Kim

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Semiconducting polymers with oligoethylene glycol (OEG) sidechains have attracted strong research interest for organic electrochemical transistor (OECT) applications. However, key molecular design rules for high-performance OECTs via efficient mixed electronic/ionic charge transport are still unclear. In this work, new glycolated copolymers (gDPP-TTT and gDPP-TTVTT) with diketopyrrolopyrrole (DPP) acceptor and thiophene (T) and vinylene (V) thiophene-based donor units are synthesized and characterized for accumulation mode OECTs, where a long-alkyl-group (C12) attached to the DPP unit acts as a spacer distancing the OEG groups from the polymer backbone. gDPP-TTVTT shows the highest OECT transconductance (61.9 S cm–1) and high operational stability, compared to gDPP-TTT and their alkylated counterparts. Surprisingly, gDPP-TTVTT also shows high electronic charge mobility in a field-effect transistor, suggesting efficient ion injection/diffusion without hindering its efficient electronic charge transport. The elongated donor unit (TTVTT) facilitates hole polaron formation to be more localized to the donor unit, leading to faster and easier polaron formation with less impact on polymer structure during OECT operation, as opposed to the TTT unit. This is supported by molecular dynamics simulation. These simultaneously high electronic and ionic charge-transport properties are achieved due to the long-alkyl-group spacer in amphipathic sidechains, providing an important molecular design rule for glycolated copolymers.

Original languageBritish English
Article number2202574
JournalAdvanced Materials
Volume34
Issue number27
DOIs
StatePublished - 7 Jul 2022

Keywords

  • accumulation mode
  • amphipathic sidechains
  • conjugated polymers
  • long-alkyl-group spacers
  • organic electrochemical transistors

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