Ultrathin‐Film Small Molecule Mixed Conductors Exhibiting Ion‐Tunable Ambipolarity for High‐Performance Organic Electrochemical Transistors and Multivalued Logic Inverters

Abstract Single‐component, ultrathin ambipolar organic electrochemical transistors (OECTs) combined with multivalued logic (MVL) circuits offer new opportunities for advancing next‐generation bioelectronic systems due to their low‐power consumption, manufacturing simplicity, and high‐density integration, central to which is the evolution of ambipolar organic mixed ionic‐electronic conductors (OMIECs) as channel materials. However, small‐molecule analogues remain unexplored to date for lack of well‐defined molecular strategies. Herein, first two acceptor‐donor‐acceptor‐donor‐acceptor‐type vinyl‐linked bis‐diketopyrrolopyrrole‐core ambipolar small‐molecule OMIECs are developed featuring multiple conformational locks. It is discovered that grafting shortened glycolated sidechains produces stronger solid‐state aggregation, tighter lamellar stacking, and higher crystallinity, consequently elevating the ambipolar µC * figure‐of‐merit by over fourfold. Furthermore, the skillful manipulation of anionic species to facilitate oxidation doping enables significant increasement in p‐type µC * (170 F cm −1 V −1 s −1 ) and a record‐high n‐type µC * of 360 F cm −1 V −1 s −1 , especially at a channel thickness of sub‐10 nm. Crucially, single‐component OECT‐based inverters constructed therefrom are for the first time demonstrated to accommodate ternary/quaternary logic, achieving a remarkable gain of 135 V/V. This work not only provides an effective molecular design strategy for creating high‐performing ultrathin‐film ambipolar small‐molecule OMIECs, highlighting ionic doping effect on ambipolarity, but also demonstrates their potential in MVL circuits for organic bioelectronics applications.