Highly-reproducible nonvolatile memristive devices based on polyvinylpyrrolidone: Graphene quantum-dot nanocomposites

Abstract

The properties of nonvolatile memristive devices (NMD) fabricated utilizing organic/inorganic hybrid nanocomposites were investigated due to their superior advantages such as mechanical flexibility, low cost, low-power consumption, simple technological process in fabrication and high reproducibility. The current-voltage (I-V) curves for the Al/polyvinylpyrrolidone (PVP): graphene quantum-dot (GQD)/in-dium-tin-oxide (ITO) memristive devices showed current bistability characteristics at 300 K. The window margins corresponding to the high-conductivity (ON) state and the low-conductivity (OFF) state of the devices increased with increasing concentration of the GQDs. The ON/OFF ratio of the optimized device was 1 x 10(4), which was the largest memory margin among the devices fabricated in this research. The endurance number of ON/OFF switching was above 1 x 10(2) cycles, and the retention time was relatively constant, maintaining a value above 104 s. The devices showed high reproducibility with the writing voltage being distributed between -0.5 and -1.5 V and the erasing voltage being distributed between 2 and 3 V. The ON state currents remained between 0.02 and 0.03 A, and the OFF state currents stayed between 10(-6) and 10(-4) A. The carrier transport mechanisms are illustrated by using both the results obtained by fitting the I-V curves and the energy band diagrams of the devices.