Fluorene based donor-acceptor polymer electrets for nonvolatile organic transistor memory device applications

Abstract

Fluorene based donor-acceptor polyimides, including poly[bis-(4-aminophenyl)fluorene-hexanediamide] [PA(BAP F-AC)], poly[bis-(4-aminophenyl)fluorene-hexafluoroisopropylidenediphthalimide] [PI(BAPF-6FDA)], poly[bis-(4-aminophenyl)fluorene-oxydiphthalimide] [PI(BAPF-ODPA)], and poly[bis-(4-aminophenyl)fluorene-1,2,4,5-cyclohexanetetracarboxylic diimide] [PI(BAPF-HPMDA)], as charge storage layer (electret) are employed for nonvolatile memory device applications. The polyimides are consisted of electron-donating fluorene diamine moiety (BAPF) and neutral (AC and HPMDA) or electron-accepting (6FDA and ODPA) moieties, respectively. The memory characteristics of these devices can be tuned from the EORM (erase once and read many times) behavior [PA(BAPF-AC)], semi-flash [PI(BAPF-ODPA)], [PI(BAPF-HPMDA)], to a flash type memory [PI(BAPF-6FDA)]. The PI(BAPF-6FDA) devices show the largest memory window of 77 V and a long retention time over 104 s with a high Ion/Ioff current ratio of 108. This is attributed to the largest torsion angle of PI(BAPF-6FDA) stabilizing charge transfer (CT) complexes. The write-read-erase-read cycles were stably operated over 100 cycles. This work provides a new insight into the relationship between the CT effect and the nonvolatile memory behavior. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 602–614