Improved Stability and Performance of an <i>n</i>-Type Depletion Mode Poly(benzodifurandione) Based Organic Electrochemical Transistor via Electrolyte Selection

Organic electrochemical transistor (OECT)-based electronic devices, known for their high transconductance and low power consumption, have garnered significant attention within the field of electrophysiology and logic circuits. Nevertheless, high-performing and stable n-type depletion-mode OECTs are highly desired to enable the implementation of more sophisticated information processing and integrated device functionalities. In this work, an n-type depletion-mode OECT based on poly(benzodifurandione) (PBFDO) is evaluated with respect to its operational stability in aqueous media. We observe that large anions effectively facilitate the dedoping process of PBFDO, resulting in a significant enhancement of its drain current ON/OFF ratio (∼103). The optimized PBFDO-OECTs show high normalized transconductance of 223 ± 43 S/cm, ultrafast transient speed of 45 μs, and high ON/OFF ratio of 103 when gated in sodium hexafluorophosphate aqueous electrolyte, capable of detecting high-resolution electrophysiological signals as well as integrating seamlessly into logic circuits, including NAND and NOR gates. Moreover, the blend of n-type PBFDO and p-type poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) for construction of a fully depletion-mode ambipolar transistor is demonstrated. Our work significantly improves the operational stability and the ON/OFF ratio of PBFDO-OECT, overcoming the performance mismatch between n-type and its counterpart p-type materials and advancing the prospects of integrated OECT in next-generation electronics.