PEDOT:Tosylate on Biocompatible Chitosan Film by Vapor Phase Polymerization: Promising Technology toward Biocompatible and Wearable Organic Electrochemical Transistor

This study presents the development of PEDOT:Tosylate‐based organic electrochemical transistor (OECT) wearable devices with a biocompatible substrate and investigates its transfer and output characteristics under bending conditions. Initial studies focused on casting chitosan film and evaluating their biocompatibility via viability assays of cultured human cells, followed by vapor phase polymerization of highly conductive PEDOT:Tosylate layers on top of chitosan films. Subsequently, the modified chitosan substrate is employed in the fabrication of OECT devices with the top‐gate bottom‐contact configuration, enabling a comprehensive characterization of its transistor performance. Accordingly, the OECT operation showed good performance metrics, with a product of volumetric capacitance and mobility (the μC * product) of the conjugated polymer layer reaching 245.75 ± 48.57 F cm −1 V −1 s −1 , a normalized transconductance of 153.59 ± 24.01 S cm −1 , and a current output retention of up to 85% after 500 cycles of ON‐OFF testing. Nanoscratch testing revealed a high critical stress of nanoscratch ( σ c ) of 497 ± 40 MPa and an adhesive energy ( G c ) of 1.91 ± 0.34 J m −2 , indicating strong resistance to delamination and peeling. Under bending conditions, the devices retained up to 81% of their initial current signal and remained as high as 97% after returning unbended.