Effect of electrode materials and fabrication methods on resistive switching behavior of poly(3-hexylthiophene-2,5-diyl)-based resistive random access memory

We evaluated a simple and economical manufacturing method to fabricate a nonvolatile (NV) memory device, which is a fully vacuum-free solution-processed organic resistive random access memory (RRAM) device. A resistive switching (RS) layer was formed from poly(3-hexylthiophene-2,5-diyl), and top electrodes were formed from solvent-treated poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and Ag epoxy. For the comparison, organic RRAM with vacuum-evaporated Ag metal top electrode were also fabricated and evaluated the RS behavior depending on the top electrode materials. All the fully vacuum-free processed RRAM devices exhibited NV and bipolar RS behavior with the best ON/OFF ratio of > 10³ and set voltage of ~ 1 V while the organic RRAM with vacuum-evaporated Ag electrode had the highest ON/OFF ratio > 10⁵ and the lowest set voltage of 0.85 V. Although RS behavior of the fully vacuum-free processed RRAM was slightly inferior to the RRAM with vacuum-evaporated electrode, its inferior performance can be compensated from its merits of simple and low-cost fabrication.