Multilevel nonvolatile transistor memories using a star-shaped poly((4-diphenylamino)benzyl methacrylate) gate electret

Multilevel nonvolatile transistor memories were fabricated using star-shaped poly((4-diphenylamino) benzyl methacrylate) (star-PTPMA) electret dielectric for charge storage and N,N'-bis(2-phenylethyl)perylene-3,4,9,10-bis(dicarboximide) (BPE-PTCDI) as an n-type semiconductor. Charges were controllably stored by applying a negative voltage bias, detected by shifting the threshold voltage, and this device retained the digital states even when the supplied voltage was removed. The multilevel data storage characteristics obtained by applying different gate voltages suggested that the device possessed nonvolatile write-many-read-many (WMRM) memory behaviors. The electronic charges were transferred and permanently accumulated in the gate electret from the restricting region of the star-PTPMA with well-defined charge trapping elements, but not in the case of linear-PTPMA. P-type pentacene was also used as a semiconductor layer to clarify the operating mechanism under a gate electric field. Our results demonstrated the significance of the architecture effect of the polymer electrets for nonvolatile organic transistor memory devices and their potentials in high-density data storage. NPG Asia Materials (2013) 5, e35; doi:10.1038/am.2012.64; published online 1 February 2013