Organic Electrochemical Transistors with Microporous Structures via Phase-Separation for Enhancing Long-Term Plasticity in Artificial Synapses

Artificial synapses, inspired by the intricate design of biological synapses, utilize electrical, chemical, and mechanical signals to transmit and retain information. Recent advances have involved research on artificial synapses based on organic electrochemical transistors (OECTs), emphasizing low power consumption and rapid response times. A notable challenge arises when the gate voltage is removed, causing doped ions to return quickly to the electrolyte. A simple yet efficient approach is used to solve this problem: forming a microporous active layer using a phase separation method. This technique can maximize the contact area between the electrolyte and the active layer, enhancing ion doping/de-doping in OECTs. Improvements in the product of hole mobility and volumetric capacitance is achieved. The electrostatic coupling effect and electrochemical doping in synaptic OECTs occur better than in the pristine active layer, yielding enhanced performance with higher short-term and long-term synaptic plasticity, compared to pristine OECTs. Moreover, improved ambipolar characteristics is shown by n-dopant injection. This paper reports a way to improve performance by simply modifying the surface shape of the active layer using the phase separation, contributing to advancements in artificial synapses for neural networks.