Polymer:nanoparticle memory devices with electrode-sensitive bipolar resistive switches by exploring the electrical contact between a bulk metal and metal nanoparticles

Abstract

Electrode-sensitive bipolar resistive switches are observed on devices with a polystyrene film blended with gold nanoparticles capped with conjugated 2-naphthalenethiol (Au–2NT NPs) sandwiched between Al and Au electrodes. The bipolar resistive switches render the devices important application as nonvolatile memory devices. This manuscript reports the operation mechanism of these polymer:nanoparticle memory devices through the analyses of conduction mechanisms, investigation of the effects of the active film thickness and the Au–2NT NP loading on the resistive switches, and Raman spectroscopy of Au–2NT NPs for the devices in two resistance states. The electrical contact between the Al electrode and Au–2NT NPs plays a key role in the resistive switches. The total resistance for the charge transport through the polymer:nanoparticle memory devices includes the resistance (Rf) for the charge transport across the active polymer:nanoparticle film and the resistance (Rc) through the electrical contact between the active film and the Al electrode. Both resistances change during the resistive switches, but the change in Rc is the dominant factor. The threshold voltage (Vth) for the resistive switch is predominantly affected by the contact between the active film and the Al electrode, and it also slightly depends on the thickness of the active film and the loading of Au–2NT NPs in the active film. The changes in Rc and Rf are ascribed to the effect of the external electric field on the charge transfer between the Al electrode and Au–2NT NPs and the electrical field-induced charge trapping on Au–2NT NPs, respectively.