The Polymer Society of Korea

Abstract

Organic electrochemical synaptic transistors (OECT-STrs) based on conjugated polymer mixed ionic–electronic conductors (CP-MIECs) are gaining attention for their unique microstructures. However, the distinct roles of crystalline and amorphous phases in electrochemical doping remain unclear. Here, we report OECT-STrs using regioblock P3HT copolymers with tunable crystallinity by varying the regiorandom fraction. With incorporating an amorphous phase in active channel of OECT-STrs, neuromorphic learning efficiency improved by enhancing the potentiation uniformity, resulting from sequential polaron formation in the amorphous phase and bipolaron formation in the crystalline phase during potentiation. Amorphous phases also enhance long-term retention at high potentiation states by promoting charge localization. Neural network simulations show devices with high amorphous content use only 18% of the power required by crystalline-rich devices due to fewer training cycles.