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

Abstract

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).