High-Performance Low Threshold Voltage n-Type OECTs via a Stepwise Cyanation of Quinoxaline-Based Polymeric Semiconductor.

Achieving both low threshold voltage (Vth) and high performance in organic electrochemical transistors (OECTs) is critical for low-power, high-sensitivity bioelectronics, yet simultaneously achieving low Vth and high device performance remains a long-standing challenge. Herein, we propose a stepwise cyanation strategy to modify quinoxaline-based polymeric semiconductors to mitigate this dilemma. Benefiting from the strong electron-withdrawing ability of cyano substituents, QxCN-CNTVT functionalized with cyano groups on both donor and acceptor units exhibits a deep LUMO level of -4.23 eV, one of the deepest among reported n-type ionic-electronic conductors. As a result, OECTs based on QxCN-CNTVT demonstrate excellent comprehensive performance, with a high µC* value of up to 168.89 F cm-1 V-1 s-1 and a low Vth of 0.13 V, while maintaining superior operational stability (retaining ∼80% of the initial current after 10,000 s of continuous operation and 10,000 full switching cycles). Furthermore, QxCN-CNTVT is successfully applied to complementary inverters for efficient amplification of electrooculogram (EOG) and electrocardiogram (ECG) signals, as well as NAND and NOR logic gates for integrated logic functions. This work not only alleviates the widely observed imbalance between performance and Vth in n-type OECTs but also provides a versatile molecular design strategy for next-generation low-power bioelectronic devices.