Unipolar nonvolatile memory devices with composites of poly(9-vinylcarbazole) and titanium dioxide nanoparticles

Organic-based devices with an 8 × 8 array structure using titanium dioxide nanoparticles (TiO2 NPs) embedded in poly(9-vinylcarbazole) (PVK) film exhibited bistable resistance states and a unipolar nonvolatile memory effect. TiO2 NPs were a key factor for realizing the bistability and the concentration of TiO2 NPs influenced ON/OFF ratio. From electrical measurements, switching mechanism of PVK:TiO2 NPs devices was closely associated with filamentary conduction model and it was found that the OFF state was dominated by thermally activated transport while the ON state followed tunneling transport. PVK:TiO2 NPs memory devices in 8 × 8 array structure showed a uniform cell-to-cell switching, stable switching endurance, and a high retention time longer than 104 s.