Flexible Memristive Devices Based on InP/ZnSe/ZnS Core-Multishell Quantum Dot Nanocomposites.

The effects of the ZnS shell layer on the memory margin of flexible memristive devices based on quantum dots (QDs) with an InP/ZnSe/ZnS, core-multishell, structure embedded in a poly(methylmethacrylate) (PMMA) layer fabricated on a conductive indium-tin-oxide (ITO)-coated polyethylene glycol naphthalate (PEN) substrate were investigated. The maximum ON/OFF ratios of the devices based on QDs with an InP/ZnSe, core-shell, structure and with an InP/ZnSe/ZnS, core-multishell, structure were approximately 4.2 × 10 and 8.5×10, respectively, indicative of an enhanced charge-storage capability in the latter. After bending, the memory characteristics of the memristive devices based on QDs with the InP/ZnSe/ZnS structure were similar to those before bending. In addition, those devices maintained the same ON/OFF ratios for retention times longer than 1 × 10 s, and their endurance number of ON/OFF-switching was above 1 × 10 cycle. The reset voltages ranged from -2.3 to -3.1 V, and the set voltages ranged from 1.3 to 2.1 V, indicative of reliable electrical characteristics. Furthermore, the carrier transport mechanisms of the devices are described on the basis of the current-voltage results with the aid of the energy-band diagram. The memristive behaviors could be attributed to the electron-trapping effect of the QDs.