A unified analytical model for antiambipolar transport in organic mixed ionic-electronic transistors

Antiambipolar transport, characterized by a bell-shaped transfer response with gate bias, has emerged as a key functionality for unconventional electronic devices, including neuromorphic circuits, single-transistor artificial neurons, and signal processing elements. Despite increasing experimental reports in organic electrochemical transistors (OECTs), a predictive understanding of the physical mechanisms governing antiambipolar behavior remains lacking, limiting rational device design. Here, we establish a general comprehensive analytical framework that captures antiambipolar transport in OECTs by explicitly coupling redox processes with electronic conduction. The model reveals that antiambipolarity arises from the competition between singly and doubly charged species, leading to a non-monotonic modulation of channel current. We derive closed-form expressions that quantitatively reproduce the transfer characteristics and identify key parameters controlling peak position, width, and magnitude. The framework provides direct design rules to engineer antiambipolar response through material properties, device geometry, and operating conditions. In fact, the model is shown to closely reproduce the response of ten commonly used p- and n-type OMIECs operated in varying electrolytes, including poly(benzimidazobenzophenanthroline) (BBL) and poly(3-hexylthiophene) (P3HT), highlighting the generality of the model and establishing a pathway to achieve this transport regime in a broad range of organic semiconductors. These results unify previous observations and enable rational design of antiambipolar functionalities in mixed ionic-electronic systems, paving the way for their broader implementation in advanced electronic systems.