Mussel-Inspired Polydopamine Coating for Flexible Ternary Resistive Memory.

In recent years, numerous organic molecules and polymers carrying various functional groups were synthesized and used in fabrication of wearable electronic devices. Compared to previous materials that suffer from poisonousness, stiffness and complex film fabrication, we circumvent above matters by taking advantage of mussel-inspired polydopamine as our active material to realize resistive random access memories (RRAMs). Polydopamine thin films were grown on indium tin oxide glass catalyzed by Cu2 SO4 /H2 O2 and characterized by Fourier infrared spectroscopy (FT-IR), UV/Vis spectroscopy and scanning electron microscopy. The Al/Polydopamine film/ITO devices possess ternary memory behavior with good ternary device yield with two threshold voltages around 1.50 V and 3.50 V, long data retention over 104  s of continuous reading or 104 pulse reading. The two resistance switchings are attributed to defects functioning as charge traps and the formation of conductive filaments. A flexible device based on Al/polydopamine film/ITO/polyethylene terephthalate retains its ternary memory behavior after being bent with a bending radius of 1.54 cm and bending cycles up to 5000, demonstrating good compatibility and flexibility of polydopamine.