Resistance Switch in a Minimal-Fullerene Chain in Vertically Stacked Electrodes

A switch element with a minimal-fullerene chain was prepared by spin coating a C60 pyrrolidine tris-acid (CPTA) film between two vertically stacked metallic electrodes. In this structure, the nanoscale length of the fullerene chain can be adjusted by changing the thickness of the CPTA film by changing spin-coating condition. The CPTA film had a rough surface that led to cause distance fluctuations between the two electrodes. At the thinnest point, a nanoscale chain could be selectively formed as a conductive channel that potentially exhibited binary resistance switching between high- and low-resistance states. This resistance change was primarily caused by the polymerization and depolymerization of the nanoscale C60 chain in response to external voltage inputs. When the film thickness was reduced to approximately 3.7 nm, corresponding to 3–4 fullerene chains bridging the two electrodes, a stable switching sequence was reproducibly achieved.