Tuning PEDOT:PSS conductivity to obtain complementary organic electrochemical transistor

Organic electrochemical transistors (OECT) have been gaining importance due to their applications in biological and chemical sensing along with logic circuitry. Most OECT studies have utilized poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as the channel material which operates in depletion mode. Here, we have used PEDOT:PSS as the channel material and have demonstrated both depletion and accumulation mode OECTs by tuning its conductivity with over-oxidation. Over-oxidized PEDOT:PSS revealed that while the PEDOT degraded PSS remained intact after oxidation leading to a reduction in the electrical conductivity leaving the ionic conductivity intact. To the best of our knowledge this is the first demonstration of the PEDOT:PSS as an accumulation OECT device. The depletion mode device exhibits a threshold voltage of −0.5 V with a transconductance of 323.6 μS as compared to the accumulation device with a threshold of 0.52 V with a transconductance of 5.19 μS. Thus, we have demonstrated the use of a single organic semiconductor for fabricating both depletion and accumulation mode OECTs. This is technologically advantageous to achieve complementary for development of sensors, logic circuits and for reduction of low power consumption of devices.