Effect of the ZnS shell layer on the charge storage capabilities of organic bistable memory devices fabricated utilizing CuInS2–ZnS core–shell quantum dots embedded in a poly(methylmethacrylate) layer

The electrical characteristics of organic bistable memory devices (OBDs) fabricated utilizing CuInS2 (CIS) core or CIS–ZnS core–shell quantum dots (QDs) embedded in a poly(methylmethacrylate) (PMMA) layer on indium–tin-oxide (ITO) coated glass substrates were investigated. X-ray photoelectron spectroscopy spectra demonstrated that the stoichiometries of the QDs embedded in a PMMA layer were CIS or CIS–ZnS QDs. Current–voltage measurements on Al/CIS or CIS–ZnS QDs embedded in PMMA layer/ITO glass devices at 300K showed current bistabilities. The maximum ON/OFF current ratios of the OBDs with CIS or CIS–ZnS QDs were approximately 1×103 and 1×105, respectively. The retention number of ON and OFF states was measured by 1×105. The memory mechanisms of the OBDs with CIS or CIS–ZnS QDs are described on the basis of the experimental results.