An all-in-one memory cell based on a homopolymer with a pyrene side chain and its volatile and nonvolatile resistive switch behaviors

Abstract

Due to their processability and flexibility, nanosheets of functional polymers showed promising applications in high capacity memory and flexional organic electronics. In this paper, we are interested in preparing a homopolymer nanofilm based ternary memory device with two different memory performances (non-volatile and volatile). Two monomers, 2-methyl-acrylic acid 4-(1-cyano-2-naphthalen-1-yl-vinyl)-phenyl ester (MNPE) and 2-methyl-acrylic acid 4-(1-cyano-2-pyren-1-yl-vinyl)-phenyl ester (MPPE), with the same structure except for the terminal conjugated group, were synthesised. Their corresponding homopolymers: PMNPE and PMPPE were obtained from monomers MNPE and MPPE by the use of the atom transfer radical polymerisation (ATRP) method, respectively. The sandwich-structure memory devices using PMNPE and PMPPE as active layers were prepared. Through the current–voltage (I–V) measurement of sandwich-structure memory devices based on PMNPE and PMPPE, memory devices based on PMNPE show binary WORM memory behaviour, while memory devices based on PMPPE exhibit a rewritable ternary memory behaviour (0, 1, 2, three conductivity states), in which the “1” and “2” states can be switched with bias switching. Their storage mechanism was speculated and discovered by experiments. The pyrene conjugated plane was much larger than that of naphthalene, so the storage mechanism for ternary behaviour involved an inversion of configuration and a charge transfer process, and the inversion of configuration was reversible and offered the rewritable behaviour. Our result provided a new ‘all-in-one’ memory cell to extend the performance of multilevel data storage devices.