All Printed Vertical Organic Electrochemical Transistor

Recently printing techniques attracted significant attention for the fabrication of electronic devices especially organic electrochemical transistors (OECTs). Printing method is a low-cost additive process with fast prototyping and compatibility with different flexible or stretchable substrates. Poly(3,4-ethylenedioxythiophene) : polystyrene sulfonate (PEDOT:PSS) is a commonly used p-type material for OECTs due to its stability in aqueous media. Most of the reported OECTs to date have large channel lengths in tens of micrometers, which limits the transistor performance and transconductance. Downscaling the channel length is challenging by a common photolithography method. Here we used the printing technique to fabricate vertical configuration of OECTs where the channel length is defined by the thickness of printed active material (PEDOT:PSS), sandwiched between source and drain electrodes (silver electrodes). Printable semi-solid gel is used as an electrolyte for devices. We compared the planar configuration with vertical devices, and significantly higher transconductance is obtained for vertical configuration.