Graphene Oxide Functionalized with Conjugated Polyelectrolyte for Nonvolatile Digital-Type Memristor and Encryption Applications

Abstract

Graphene and its derivatives-based molecular computation has ignited a revolution in global microelectronics industry due to their exceptional electronic quality and the transport properties. Current challenges include the optimization of low-temperature CMOS compatible processes and the improvement of large-scale production stability, but the collaborative development of the two-dimensional material family is accelerating technological breakthroughs. To switch graphene oxide (GO) between ON and OFF states in nanoelectronic memory devices, a novel conjugated polyelectrolyte, poly[9,9-bis(6ʹ-(3-methyl-1-imidazolium-yl)hexyl)- fluorene-alt-1,1,2,2-tetraphenylethene] (PFTPE-NMI+Br-), is non-covalently attached onto the GO surface to give the PFTPE-NMI+Br-:GO blends in which PFTPE-NMI+Br- acts as electron donor and GO serves as electron acceptor. The as-fabricated electronic device with a configuration of Al/ PFTPE-NMI+Br-:GO/ITO shows a nonvolatile ternary rewritable memory effect, with a switch-off voltage of +2.29V and two switch-on voltages of -1.22 and -2.03V. The observed OFF:ON1:ON2 current ratio reached up to 1:90:40000. This result can be assigned to the combination of two kinds of the charge transfer processes in the material system: one from PFTPE-NMI+Br- to GO, and another from the polymer backone to the imidazolium moieties. In contrast to PFTPE-NMI+Br-:GO, the PFTPE-NMI+Br-- based electronic device only shows write-once-read-many-times (WORM) memory performance, with a switch-on voltage of -1.45V. By taking advantage of the outstanding ternary memory performance and high OFF:ON1:ON2 current ratio exhibited by the device, a logic gate circuit encryption unit based on OR, XOR and AND logic gates has been constructed.