Nonvolatile transistor memory devices based on high-k electrets of polyimide/TiO2 hybrids

Novel nonvolatile memory behaviors of n-type N,N′-bis(2-phenylethyl)-perylene-3,4,9,10-tetracarboxylic diimide (BPE-PTCDI) based organic field-effect transistors (OFET) using the new polyimides (PIs), (poly[9,9-bis(4-(4-amino-3-hydroxyphenoxy)phenyl)fluorene-oxydiphthalimide]) PI(F-ODPA) and (poly[4,4′-bis(4-amino-3-hydroxyphenylthio)diphenyl sulfide-oxydiphthalimide]) PI(3S-ODPA), and their PI/TiO2 hybrids as electrets are reported. The OFET memory devices derived from PI(F-ODPA) with π-conjugated fluorene moieties exhibited a larger memory window (8.6 V), and could be further enhanced by introducing TiO2 (up to 20 wt%) into the PIs. In addition, PI/TiO2 hybrids as electrets for memory devices also could effectively reduce the operating voltage, indicating that the charge transfer capability of TiO2 plays an important role in transferring and storing the charge for OFET memory devices.