Improved neuromorphic functionality in organic electrochemical transistors using crosslinked-polyvinyl alcohol for fast ion transport and its application to Pavlovian transistors†

Abstract

Organic electrochemical transistors (OECTs) hold significant promise for bioelectronics and neuromorphic computing due to their efficient ion-electron coupling and low operating voltage. However, conventional OECTs based on hydrophobic conjugated polymers such as poly(3-hexylthiophene) (P3HT) suffer from limited ion penetration, which restricts transconductance, response speed, and synaptic plasticity. To address these limitations, a cross-linked polyvinyl alcohol (CX-PVA) interlayer is introduced to enhance ion transport and improve device performance. The hydrophilic nature and strong water retention of CX-PVA facilitate efficient ion diffusion, thereby strengthening electrolyte–active layer interactions. CX-PVA/CX-P3HT OECTs were fabricated and their electrical and synaptic properties systematically analyzed. Notably, the incorporation of CX-PVA led to an increase in transconductance from 0.01 to 1.41 mS an improvement of approximately 140-fold—and enhanced the on/off current ratio from 1.4 × 10² to 2.5 × 10³. Furthermore, the superior ion transport enabled stronger excitatory postsynaptic current (EPSC), improved paired-pulse facilitation (PPF), and prolonged long-term potentiation (LTP), underscoring the potential of CX-PVA as a key enabler for high-performance neuromorphic computing.