Printed electrochemical devices using conducting polymers as active materials on flexible substrates

This paper reports some of our initial works in pursuit of a simple and low-cost method of fabricating all-organic electrochemical diodes, triodes, and transistors on flexible plastic or paper substrates. Conducting polymer poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT: PSS), utilized as an active component, is deposited by spin-coating or printing techniques. The devices are directly fabricated from design without the need for masks, patterns, or dies. The output characteristics of both half-wave and full-wave rectifier circuits from two-terminal diodes show stable performances at frequencies below 5 Hz. In three-terminal tunable triodes, threshold voltage can be tuned in the range between 0.25 and 1.6 V In Jour-terminal transistors, ambipolar operation function can be realized in one single device. I-ON/I-OFF current ratios of 10(3)-10(4) have been achieved in the triode and transistor at operating voltages below 3 V In addition, the device applications in electrochromic displays, logical circuits, as well as the switching speed of the circuits and device stability, are discussed.