Abstract-A novel vertical architecture for all-printed organic electrochemical transistors, based on PEDOT:PSS, realized on flexible substrates is reported. The transistors are manufactured along both faces of paper or plastic substrates and via connections are realized using laser ablation and simple punch through using a pin. Successful modulation of the electric current that flows between the two sides of the substrate is achieved using electrolyte-gating and electrochemical modulation of the electronic charge transport of the bulk of the transistor channel. In addition to this, the transistors are exhibiting fast switching and high on/off current ratios.
Introductionuring the last decade the research field of printed electronics (PE) has experienced a tremendous advancement in terms of the performance of single electronic devices, complexity of functional printed systems, and also regarding potential application areas [1][2][3][4][5]. One of the prime key criteria to success with the printed-on-paper and printed-on-plastic electronics revolution is that simple and robust device architectures are developed so that large area, high throughput and low cost manufacturing techniques can be used. Various qualities of flexible plastic foils and cellulose-based papers are explored as the carrying substrates for PE, of which paper nowadays attracts an increased attention in part thanks to its environmentally friendly characteristics [6]. Various sensors [7], thin film transistors (TFTs) [8], displays [9] and supercapacitors [10] have been realized on paper and plastic foils [8,11,12]. Moreover, different high volume sheet-based or roll-to-roll printing, coating and lamination tools have been successfully utilized to manufacture complete device systems. However, the device structure of many PE components typically mimics the architecture of devices developed for electronics manufactured using inorganic rigid substrates such as silicon, or thin film devices produced using various evaporation and sputtering methods. Improvements in performance obtained in inorganic-based technologies have in part been achieved by using multi-stack structures [13,14]. A similar strategy could be utilized also for organic electronic components by constructing device architectures in a vertical configuration; for instance by printing materials on top of each other and to connect devices defined on both sides, using electrical vias, of the carrying flexible substrate to improve integration density and operation performance [15,16]. Here, we report such an electrical via approach to achieve organic electrochemical transistors (OECT), based on poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrene sulfonate) (PSS), that exhibit improved drain current switch on/off-ratio and switch time characteristics. The vertical OECTs have been realized on both paper and plastic substrates with electrical vias based on carbon paste. The gate, source, electrolyte and PEDOT:PSS channel are all located on the same side of the substrate, whereas the ...