New one-pot poly(3,4-ethylenedioxythiophene): Poly(tetrahydrofuran) memory material for facile fabrication of memory organic electrochemical transistors

The discovery of a new poly(3,4-ethylenedioxythiophene) (PEDOT) composite with unique memory characteristics has led to the demonstration of durable Organic ElectroChemical Transistors (OECT) based memory devices. The composites of PEDOT with polytetrahydrofuran undergo a structural collapse during electrochemical reduction that requires approximately 800 mV overpotential to re-open and is thus hindering the re-oxidation of the composite. This effect causes the composite at intermediate potentials to be able to have two different oxidation states and thereby resistances, depending on the "on" or "off " switching potential applied prior to the intermediate potential. Notably, this hysteresis is lasting over time and no drift has been observed. Impedance spectroscopy, in-situ UV-Vis spectroscopy, conductivity measurement, in-situ electrochemical quartz crystal microbalance, and differential scanning calorimetry were used to confirm and explain the switching memory phenomena. The OECT platform was used to validate the PEDOT:PTHF as a one-pot memory source-drain material where a threefold increase in drain current was observed between "off " and "on" mode of the transistor after modulation of the Ag/AgCl gate.