In this study, we demonstrate solution-processed memristor devices using a CdSe/ZnS colloidal quantum dot (CQD)/poly(methyl methacrylate) (PMMA) composite and their electrical characteristics were investigated. Particularly, to obtain stable memristive with large current switching ratio, the concentration of QDs in PMMA matrix was optimized. It found that QD 1 wt%, device exhibited high ratio ~...