Inter‐Ion Mutual Repulsion Control for Nonvolatile Artificial Synapse

Abstract Organic electrochemical transistors (OECTs) are promising candidates for artificial synapses to achieve high‐performance synaptic characteristics. While most research has focused on modifying the properties of organic semiconductors for efficient ion doping, there is a lack of systematic investigation into the relationship between ion‐mediated mechanisms and synaptic performance. In this study, an effective strategy for enhancing electrochemical doping and de‐doping by utilizing different coulombic anions is proposed. The findings reveal that doped ions in the channel layer affect inter‐ion interactions, influencing the non‐volatile effects by improving the doping performance of the synaptic device. Moreover, electrochemical analysis indicates that ions in the channel layer are sequentially de‐doped, enabling high linearity and symmetry. The fabricated devices demonstrate high‐performance synaptic properties including a retention time of ≈10² s with ≈50% retention over peak current and near‐ideal long‐term potentiation/long‐term depression (LTP/LTD) through effective electrochemical doping and de‐doping. These results show that controlling both the properties of organic semiconductors and ion interactions in the electrolyte is crucial for OECTs, opening up various applications for neuromorphic computing.