Multi-functional polyimides containing tetraphenyl fluorene moieties: fluorescence and resistive switching behaviors

Abstract

Two novel aromatic polyimides (PIs), TPF27OPI and TPF99OPI, with a tetraphenyl fluorene (TPF) unit as the electron donor (D) and a 4,4′-oxydiphthalic dianhydride (ODPA) unit as the electron acceptor (A) were synthesized and characterized. Both of the as-synthesized PIs showed obvious photoluminescence properties, and compared with TPF27OPI, where the fluorene unit is located in the polymer main chain, TPF99OPI with a fluorene unit in the side chain showed stronger fluorescence and a fluorescence blue shift in the film state. The memory device with a sandwich configuration of ITO/TPF27OPI/Al showed the nonvolatile “write once, read many” (WORM) switching behavior, while that of ITO/TPF99OPI/Al exhibited “static random access memory” (SRAM) switching behavior. Both of the devices exhibited a stable ON/OFF current ratio above 10⁴ and a long operation time, following 10⁴ pulse reading cycles with no obvious degradation in current. The mechanism of the resistive switching behaviors was discussed using the experimental and molecular simulation results. These multi-functional polyimides showed attractive potential applications in the field of polymer optoelectronic devices and memory devices.