Ether-Linkage-Mediated Ion Stabilization in Organic Artificial Synapses for Memory Regulation

Organic electrochemical transistors (OECTs) have emerged as promising platforms for artificial synapses because their ion-driven electrochemical modulation resembles key processes in biological synaptic transmission. However, achieving long-lasting synaptic memory remains challenging due to the limited residence time of mobile ions within organic channels. In this study, we introduce a molecular design strategy that incorporates ether linkages into the conjugated polymer backbone to regulate ion–polymer interactions and enhance memory retention in OECT-based artificial synapses. Complementary experimental and theoretical analyses reveal that ether linkages play a dual role in facilitating ion penetration and stabilizing the doped state. The flexible ether-linked backbone lowers the energetic penalty for structural rearrangement during ion doping, reducing steric constraints and enabling diffusion-dominated deep channel doping. Simultaneously, the strong affinity between ether linkages and infiltrated ions increases adsorption energy, effectively suppressing ion back-diffusion from the channel. As a result, the artificial synapse exhibits an exceptionally prolonged memory decay lasting up to 10⁵ second, surpassing the ion retention limits commonly observed in conventional OECT-based synaptic devices. Furthermore, its decay behavior closely follows the Ebbinghaus forgetting curve, indicating that biologically relevant memory dynamics can be quantitatively emulated in organic electronic devices. These findings establish ether-linkage engineering as an effective molecular design principle for overcoming ion retention limitations and provide a pathway toward neuromorphic hardware capable of reproducing human-like memory functions.