Memory stabilities and mechanisms of organic bistable devices with giant memory margins based on Cu2ZnSnS4 nanoparticles/PMMA nanocomposites

Abstract

Organic bistable devices (OBDs) were fabricated utilizing nanocomposites made from a blend of Cu2ZnSnS4 (CZTS) nanoparticles within a polymethyl methacrylate (PMMA) matrix on a polyethylene terephthalate substrate. Energy dispersive X-ray spectroscopy profiles, X-ray diffraction patterns, and high-resolution transmission electron microscopy images showed that the polycrystalline CZTS nanoparticles were randomly distributed in the PMMA layer. The current-voltage (I-V) curves at 300 K for the fabricated OBDs showed bidirectional switchable and current hysteresis behaviors, indicative of the removal of sneak current paths without an additional layer with characteristics of diode or selector. The removal of the sneak current paths prevented the leakage current of the OBDs, resulting in an increase of the current of high conduction (ON) level. The maximum ON/low-conduction (OFF) ratio of the current bistability for the fabricated OBDs was as large as 1 x 10(9). The write-read-erase-read sequences of the OBDs showed rewritable nonvolatile memory behaviors. The ON or the OFF states could be retained for 1 x 10(5) cycles, indicative of excellent memory stability. The ON/OFF ratio of 10(9) was maintained after 10(5) cycles. The memory mechanisms of the fabricated OBDs are described on the basis of the I-V results. (C) 2015 Elsevier B.V. All rights reserved.