Role of oxadiazole moiety in different D-A polyazothines and related resistive switching properties

Two donor-acceptor (D-A) polyazothines (PAs), incorporating the oxadiazole entity either acting as an electron acceptor (A) to form D-A structured PA-1 with the triphenylamine donor (D), or acting as a donor to form D-A structured PA-2 with the 3,3'-dinitro-diphenylsulfone acceptor, have been successfully synthesized via a polycondensation reaction. The variation in the role of the oxadiazole moiety in the D-A polymers, together with the use of different top electrode metals, leads to interesting electronic transport properties and various resistive switching behaviors of the present polyazothines. Pt-electrode devices based on a PA-1 active layer show a rewritable memory effect with poor endurance (less than 20 cycles), whereas the PA-2 based Pt devices exhibit write-once read-many-times (WORM) memory behavior. For the Al-electrode devices, both PAs demonstrate a much improved resistive switching effect, and the endurance of the PA-2 devices is better than that of the PA-1 devices. The difference in the electronic transport and memory properties of the four devices may originate from the different charge injection/extraction and electron transfer processes of the sandwich systems, and will provide guidelines for selecting both the proper D and A moieties in D-A polymers and electrode metals for high-performance resistance random access memories (RRAMs).