Nonvolatile ternary memory devices were fabricated using the composite of polystyrene (PS) and graphene oxide(GO) as active layers, which have an reliable intermediate state. The current-voltage (I-V) curves of the indium tin oxide (ITO)/PS+GO/Al device under the external applied voltages exhibited current tri-stability with three conductivity states, which clearly revealed ternary memory performance. Under the stimulus of the external voltage, a stable intermediate conductivity state was observed. In the write-read-erase-read test, the ITO/PS+GO/Al device exhibited rewritable, nonvolatile, ternary memory properties. The resistance as functions of the time indicated that three conductivity states held for 2 × 105 s, suggesting that the good stability of the ITO/PS+GO/Al devices. HRTEM and XPS observation indicated that the Al top electrode reacted with oxygen within in GO.

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A novel multilevel resistive switching was observed in epoxy methacrylate resin (EMAR) and carbon nanotubes (CNTs) composite films fabricated by spin coating method. The fabricated devices demonstrated the rewritable nonvolatile memory characteristics. More significantly, the memory device based on EMAR+CNTs composite exhibits multilevel stable conductivity states with stable intermediate resistance states in response to the applied voltage. By setting different compliance current and content of CNTs in composite film, the multilevel ON-states and even the multilevel OFF-states have been observed in our memory device. As fabricated devices exhibited multilevel resistive switching with stable resistance ratio between different resistance states having good data retention and endurance characteristics. It offers a novel design strategy for solution processable multilevel data storage.

Nonvolatile memory devices based on active layers of poly(vinyl alcohol) (PVA) + graphene oxide (GO) hybrid composites have been fabricated. The performance of the ITO/PVA + GO/Al device was compared with that of the ITO/PVA/Al device. The ITO/PVA + GO/Al device showed excellent performance compared to the ITO/PVA/Al device (an ON/OFF resistance ratio of 1.2 × 10(2) at 1 V, V(SET )∼ -1.45 V and V(RESET) ∼ 3.6 V), with a higher ON/OFF resistance ratio of 3 × 10(4) at 1 V and lower operating voltages of V(SET) ∼ -0.75 V and V(RESET) ∼ 3.0 V. Furthermore, endurance performance and write-read-erase-reread (WRER) cycle tests manifest that the presence of GO in ITO/PVA + GO/Al devices makes them have better stability and repeatability. The results show that the performance of hybrid devices can be effectively enhanced by the introduction of GO into the PVA matrix.