High-Performance Synaptic Devices Based on Cross-linked Organic Electrochemical Transistors with Dual Ion Gel

Organic electrochemical transistors (OECTs) represent a promising approach for flexible, wearable, biomedical electronics, and sensors integrated with diverse substrates. Their ability to operate at low voltages and interact effectively with biological systems makes them particularly suitable for neuromorphic applications. For neuromorphic devices, OECTs must enhance electrical performance, biocompatibility, and signal storage/erasure capabilities. While UV cross-linking methods with various side effects on organic semiconductors are predominant in improving mobility and current retention time, thermal cross-linking based on the solution process has not been extensively explored. Additionally, despite significant research on the modification of electrolyte property, the ionic charge compensation mechanisms between multiple electrolytes are still unclear. This study employs a cross-linking strategy involving the chemical reaction of poly(3-hexylthiophene-2,5-diyl) (P3HT) with di-tert-butyl-peroxide (DTBP) to create a cross-linked P3HT active layer. Furthermore, a dual ion gel structure combining a conventional ion gel with a chitosan-based ion gel is investigated for increased ionic transport to enhance OECT performance. Using the above two methods, the enhanced electrical performance showing the mobility of 25 F cm⁻¹ V⁻¹ s⁻¹ and synaptic properties showing long-term plasticity of cross-linked OECTs with a dual ion gel structure are demonstrated, suggesting their potential application as high-performance neuromorphic devices.