Hydrogen-Bond–Driven Ion Retention in Electrolyte-Gated Synaptic Transistors

Electrolyte-gated synaptic transistors (EGSTs) have emerged as promising neuromorphic devices capable of modulating synaptic weights via ion-mediated control. However, the correlations between ion–polymer interactions and ion-doping retention characteristics remain poorly understood. Notably, strategies that simultaneously control ion–polymer interactions and synaptic retention via electrolyte ions as independent design variables remain underexplored. In this study, we demonstrate that hydrogen-bond-mediated anion–polymer interactions play a central role in governing synaptic retention. Anions with asymmetric charge distribution give rise to strengthened hydrogen-bond interactions, which regulate ion dynamics and suppress ion back-diffusion. This hydrogen-bond interaction effectively transforms ion relaxation behavior from a diffusion-dominated to an interaction-stabilized regime within the organic semiconductor. As a result, the devices exhibit enhanced synaptic retention together with excellent linearity during long-term potentiation/depression (LTP/D). These findings provide molecular insight into hydrogen-bond-mediated synaptic retention in EGSTs, offering a mechanistic basis for the rational optimization of ion-driven neuromorphic devices.