Fibrillary gelation and dedoping of PEDOT:PSS fibers for interdigitated organic electrochemical transistors and circuits

As one of conducting polymers, PEDOT:PSS, is commonly used in organic electronics, especially for bioelectronics due to its advantages such as high electrical and ionic conductivity, solution-processability and biocompatibility. Creating bioelectronics with the PEDOT:PSS requires advanced techniques to obtain physical/chemical modification of the PEDOT:PSS for improved performance and various applications. To satisfy these demands, fibrillary gelation of PEDOT:PSS by injection to choline acetate, an ionic liquid, with a constant flow rate was used in this study to make a conductive fiber and improve characteristics of PEDOT:PSS. Conductive fibers by fibrillary gelation showed enhanced electrical conductivity of about 400 S cm⁻¹ and volumetric capacitance of about 154 F cm⁻³ which would be strongly beneficial to be utilized for organic electrochemical transistors (OECTs), resulting in a high transconductance of 19 mS in a depletion-mode. Moreover, dedoping of the conductive fibers by PEI (polyethyleneimine) enabled the creation of enhancement-mode OECTs. Interdigitated inverters were then fabricated by connecting depletion and enhancement-mode OECTs. These results demonstrate that these conductive fibers and electronic-textiles are suitable candidates for applications in bio-integrated electronics.