Regular and Inverted Hysteresis in Organic Electrochemical Transistors: Mechanisms and Electrochemical Insights

Organic electrochemical transistors (OECTs) are one of the most versatile electronic devices, offering great potential applications from bioelectronics and smart sensors to analog neuromorphic computing, owing to their unique electronic‐ionic coupling characteristics. However, despite their considerable success, the complex interplay between electronic and ionic charge carriers leads to various anomalous device behaviors that are still poorly understood, hindering their practical application. For instance, OECTs often exhibit different hysteresis behaviors in their transfer characteristics and asymmetry in switching during turn‐on and turn‐off operations. Herein, the evolution of hysteresis in the transfer curves of OECTs as a function of delay time and channel length is systematically investigated, employing a range of electrochemical measurements. The findings reveal that the transition from regular hysteresis to inverted hysteresis is governed by the interplay between ion injection and extraction dynamics, which is closely linked to the open circuit potential (OCP) of the electrolyte‐semiconductor interface. This work provides valuable electrochemical insights into the device physics of OECTs, paving the way for future optimization and advancement of these devices for practical implications.