Enhanced Electrochemical Response and Device Speed in Diketopyrrolopyrrole/PEO Composite Channels

Abstract

Achieving efficient charge conduction in organic electrochemical transistor(OECT) channel materials requires a delicate balance between electronicconduction and ion uptake. Common approaches to this challenge focus ontethering hydrophilic side chains to conjugated backbones, often resulting incomplex synthetic routes. Herein, an alternative strategy is presented usingcomposite mixed-conductive materials. Specifically, polyethylene oxide (PEO),a hydrophilic polymer, and a diketopyrrolopyrrole-based semiconductor,renowned for electronic conduction and processability, are used in varyingratios to form composite films with tunable mixed conduction and enhancedOECT performance. The effect of incorporating PEO on the composite’smorphology and OECT performance in both aqueous and non-aqueouselectrolytes is investigated. At the nanoscale, PEO is found to not onlyenhance channel hydrophilicity and ion uptake but also electrochemical gatingspeed, leading to improved OECT performance. These enhancements inelectrochemical performance are correlated with the morphological propertiesof the composite via structural and in-situ spectro-electrochemicalcharacterizations. Furthermore, the composite’s response is found to varywith the electrolyte environment: in organic electrolytes such as1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI),it exhibits high-speed performance suitable for neuromorphic applications,while in aqueous electrolytes, it achieves robust ion uptake ideal forbioelectronics. These findings highlight the potential of composite designs foroptimized OECT functionality across applications.