A high-performance organic electrochemical transistor based on foam-structured channels prepared using a template washing-off method

Organic electrochemical transistors (OECTs) are promising for chemical/biological sensing and health monitoring due to their signal amplification and low operating voltage. Transconductance and response time are two important parameters for OECTs, determining their sensitivity. However, it is still a great challenge to simultaneously improve the transconductance and decrease the response time of OECTs for more sensitive detection. Herein, a foam-structured PEDOT:PSS film is fabricated for the preparation of a high-performance OECT by using a template washing-off method. The isolated ionic liquid domains are used as the template for fabrication of a foam-structured film. Compared with that of a solid PEDOT:PSS film, the electrical conductivity of the foam-structured PEDOT:PSS film improves from 0.2 to 573.7 S cm⁻¹ and the volumetric capacitance increases five folds to 71.80 F cm⁻³. In addition, the ion doping/de-doping becomes more efficient in the foam-structured PEDOT:PSS film. As a result, the OECT based on this foam-structured PEDOT:PSS demonstrates an increase in transconductance from 90 μS to 18 mS and a decrease in response time from 1000 to 300 millisecond. Due to the improved transconductance and a shortened response time, the OECT exhibits sensitive detection of chemicals and metabolites, such as hydrogen peroxide and glucose. This work provides a new and simple strategy for fabricating high-performance OECTs, which may be used in various wearable applications, including biological detection or health monitoring.