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

Abstract

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.