Realizing Ultrahigh Transconductance in Organic Electrochemical Transistor by Co‐Doping PEDOT:PSS with Ionic Liquid and Dodecylbenzenesulfonate

Organic electrochemical transistors (OECTs), especially the ones with high transconductance, are highly promising in sensitive detection of chemical and biological species. However, it is still a great challenge to design and fabricate OECTs with very high transconductance. Herein, an OECT with ultrahigh transconductance is reported by introducing ionic liquid and dodecylbenzenesulfonate (DBSA) simultaneously in poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) as the semiconductive channel. Compared with the OECT based on pristine PEDOT:PSS, the OECT based on co-doped PEDOT:PSS demonstrates a significant enhancement of transconductance from 1.85 to 22.7 mS, because of the increase in volumetric capacitance and conductivity. The enhanced transconductance is attributed to the DBSA-facilitated phase separation between the ionic liquid and PEDOT:PSS, which helps to form conductive domains of ionic liquid in PEDOT:PSS matrix, and the partial dispersion of ionic liquid in the PEDOT:PSS phase. Furthermore, by using the interdigitated electrodes as the source and drain electrodes, an ultrahigh transconductance of 180 mS is obtained, which is superior to that of the state-of-the-art OECTs. Because of the ultrahigh transconductance, the obtained OECT demonstrates sensitive detection of hydrogen peroxide and glucose, making it promising in clinical diagnosis, health monitoring, and environmental surveillance.