From Tape to Transistor: A Low-Cost and Cleanroom-Free Route to Flexible Vertical Organic Electrochemical Transistors

Vertical organic electrochemical transistors (vOECTs) combine high current density, large transconductance, and fast switching speeds, clearly outperforming traditional planar OECTs. These features make them highly attractive for high-sensitivity and high-frequency applications, including biosensing and neuromorphic computing. However, current fabrication methods remain complex and costly, typically requiring cleanroom facilities and advanced microfabrication techniques. Here, we introduce a low-cost, cleanroom-free approach to fabricating flexible vOECTs by thermally evaporating gold onto commercial polyimide tape. This straightforward process eliminates the need for lithography or shadow masks, simplifying device production. The resulting transistors show high transconductance, excellent ON/OFF ratios, and stable operation. Furthermore, their integration into a unipolar inverter highlights their suitability for organic electronic circuits. Overall, this work presents an accessible and scalable fabrication route for flexible vOECTs, opening opportunities for next-generation bioelectronic and computing platforms.