High-Transconductance Organic Electrochemical Transistor Fabricated on Ultrathin Films Using Spray Coating

Organic electrochemical transistors (OECTs) are widely used for monitoring electrophysiological activities by exploiting advantages, such as flexibility, biocompatibility, low-voltage operation, and high transconductance. Transconductance is a major factor that determines the sensitivity of OECT-based sensors. In comparison with other field-effect transistors, the transconductance of OECTs having the poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) channel layer is proportional to the channel thickness because the entire film acts as a channel. Therefore, the formation of a thick channel layer is essential for OECTs. However, it is difficult to form a thick film by spin coating. Herein, spray coating is introduced, and a thick and uniform PEDOT:PSS layer (1.05 mu m) is successfully formed by controlling the compressed air pressure and number of coating cycles. Moreover, a high-transconductance (7.5 mS) ultraflexible OECT with a sufficiently rapid response is fabricated (2.3 kHz).

Automated summary

Organic electrochemical transistors (OECTs) are widely used for monitoring electrophysiological activities, with the transconductance of OECTs using PEDOT:PSS channel layer being proportional to the channel thickness, which is essential for forming a thick channel layer; spray coating technique can successfully form a thick and uniform PEDOT:PSS layer, resulting in a high-transconductance and ultraflexible OECT with a sufficiently rapid response.