Electrical and mechanical stability of flexible, organic electrolyte-gated transistors based on iongel and hydrogels

Abstract

Electrolyte-gated transistors (EGTs) have been widely investigated for applications in bioelectronics owing to their low operating voltage and mixed ionic–electronic conduction. The ion-gating media play a primary role in determining the operating voltage and electrical stability of these devices. In this study, we employed an iongel based on an ionic liquid and hydrogels based on polyvinyl alcohol (PVA) as the gating media for EGTs using the organic semiconductor poly(N-alkyldiketopyrrolo-pyrrole-dithienylthieno[3,2-b]thiophene) (DPP-DTT) as the channel material. The device characteristics revealed that iongel-gated transistors showed superior electrical stability over hydrogel-gated transistors, because hydrogels undergo dehydration over time. After 65 cycles of pulse measurements, the drain current of the iongel-gated devices did not show any significant change, whereas it decreased to ∼50% of the initial value for the hydrogel-gated devices. By adding glycerol as an anti-dehydrating agent, the current decreased by only ∼10% under the same conditions, demonstrating improved operational stability. Finally, we fabricated flexible EGTs on polyethylene terephthalate (PET), which can be operated under different bending radii.