Understanding the role of electrode composition on the current-voltage response of Cu/PEDOT: PSS/ITO memristive device.

Resistive switching devices with metal/PEDOT:PSS thin film/metal sandwich configuration, display pinched hysteretic current-voltage (i-v) response to periodic voltage input, a signature of memristors. Several studies have focused on revealing the switching mechanism using symmetric electrode materials like Gold (Au) or Aluminum (Al). Realizing the influence of asymmetric electrode composition on the i-v response of PEDOT:PSS, using copper (Cu) as an electrode material is currently missing. Therefore, our objective is to study the role of Cu on the memristive i-v response of Cu/PEDOT:PSS/ Indium Tin Oxide (ITO) devices.

Here we build microscale planar electrodes of different compositions (Cu, Au, ITO) on non-conductive silicon wafers with an inter-electrode gap of 5 µm. We spin-coat PEDOT:PSS onto the electrodes. Initial i-v analysis shows fading of hysteresis across cycles for Cu-Cu electrode devices and no hysteresis for Au-Au devices. These results differ from the bipolar hysteretic i-v response we observed repeatedly in vertically stacked Cu/PEDOT:PSS/ITO devices with macroscale electrodes. These results highlight the importance of using dissimilar electrode materials to achieve bipolar resistive switching in PEDOT:PSS memristors. Therefore, through i-v measurements and microscopy techniques, we aim to reveal the role of dissimilar electrodes on the switching mechanism of the planar Cu/PEDOT:PSS/ITO device.