Volatile electrical switching and static random access memory effect in a functional polyimide containing oxadiazole moieties

Abstract

A solution-processable functional polyimide, P(BPPO)-PI, containing oxadiazole moieties (electron donors) and phthalimide moieties (electron acceptors) was synthesized. A switching device, based on a solution-cast thin film of P(BPPO)-PI sandwiched between an indium-tin oxide (ITO) bottom electrode and an Al top electrode, exhibits two accessible conductivity states and can be switched from the low-conductivity (OFF) state to the high-conductivity (ON) state when swept positively or negatively, with anON/OFFcurrent ratio on the order of 1×104. The device exhibitsON state "remanence", with the ON state retainable for a period of about 4 min after turning off the power. The ON state can be electrically sustained either by a refreshing voltage pulse of-1 V or by a continuous bias of-1 V. The "remanent" but volatile nature of the ON state and the ability to write, read, and sustain the electrical states with bias are characteristic features observed in a static random access memory (SRAM). The mechanisms associated with the memory effect were elucidated from molecular simulation results and changes in the photoelectronic spectrum of P(BPPO)-PI film when the device was switched between the ON and OFF states. © 2009 American Chemical Society.