Small-Molecule Mixed Ionic-Electronic Conductors for Efficient N-Type Electrochemical Transistors: Structure-Function Correlations

Yongjoon Cho, Lin Gao, Yao Yao, Jaehyun Kim, Dayong Zhang, Giacomo Forti, Isaiah Duplessis, Yuyang Wang, Robert M. Pankow, Xudong Ji, Jonathan Rivnay, Tobin J. Marks, Antonio Facchetti

Research output: Contribution to journalArticlepeer-review

Abstract

The fundamental challenge in electron-transporting organic mixed ionic-electronic conductors (OMIECs) is simultaneous optimization of electron and ion transport. Beginning from Y6-type/U-shaped non-fullerene solar cell acceptors, we systematically synthesize and characterize molecular structures that address the aforementioned challenge, progressively introducing increasing numbers of oligoethyleneglycol (OEG; g) sidechains from 1 g to 3 g, affording OMIECs 1gY, 2gY, and 3gY, respectively. The crystal structure of 1gY preserves key structural features of the Yn series: a U-shaped/planar core, close π–π molecular stacking, and interlocked acceptor groups. Versus inactive Y6 and Y11, all of the new glycolated compounds exhibit mixed ion-electron transport in both conventional organic electrochemical transistor (cOECT) and vertical OECT (vOECT) architectures. Notably, 3gY with the highest OEG density achieves a high transconductance of 16.5 mS, an on/off current ratio of ~106, and a turn-on/off response time of 94.7/5.7 ms in vOECTs. Systematic optoelectronic, electrochemical, architectural, and crystallographic analysis explains the superior 3gY-based OECT performance in terms of denser ngY OEG content, increased crystallite dimensions with decreased long-range crystalline order, and enhanced film hydrophilicity which facilitates ion transport and efficient redox processes. Finally, we demonstrate an efficient small-molecule-based complementary inverter using 3gY vOECTs, showcasing the bioelectronic applicability of these new small-molecule OMIECs.

Original languageEnglish
Article numbere202414180
JournalAngewandte Chemie - International Edition
Volume64
Issue number2
DOIs
StatePublished - 10 Jan 2025

Keywords

  • electrochemical transistor
  • ion transport
  • mesh-like crystal
  • n-type small molecule
  • organic mixed ionic-electronic conductor

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