Controlled Nonvolatile Transition in Polyoxometalates-Graphene Oxide Hybrid Memristive Devices

Graphene oxide (GO)-based nonvolatile memory has triggered tremendous interest owing to its high mechanical flexibility, high optical transparency, low cost fabrication, and environmental friendly manufacture for future flexible and transparent electronic devices. Although various data storage types with different switching mechanisms have been demonstrated, challenges still exist in controlling of the memory performances. Here, polyoxometalates (POMs), a type of molecular oxide cluster, is coassembled into the GO-based memory through electrostatic layer-by-layer deposition approach. Assisted by the catalytic activity of POMs, the GO can be reduced to reduced graphene oxide (RGO) under UV irradiation. By this catalytic photoreduction reaction, two types of memory characteristics can be obtained including the write-once-read-many-times (WORM) derived from the GO-based memory and the rewritable bipolar resistive switching arising from the RGO-based counterpart. It was verified that the transition between the WORM and bipolar resistive switching is associated with the modulation of the interface barrier of POM and GO junction. Furthermore, charge trapping/detrapping process is proposed to account for the mechanism of the two memory types. This work offers valuable insight into the new design of tunable memory characteristics and emphasizes the significant role of POMs in modifying the interface features.