Tailoring the Resistive Switching WORM Memory Behavior of Functionalized Bis(triphenylamine)

To better understand the structure-property relationship and the significance of the donor-acceptor (D-A) system in resistive memory devices, a series of new organic small molecules with A -N-D -N -A-and D -N-D -N-D-based architecture comprising a bis(triphenylamine) core unit and ethynyl-linked electron donor/acceptor arms were designed and synthesized. The devices with A -N-D -N-A structures exhibited write-once-read-many memory behavior with a good retention time of 1000 s while those based on D -N-D -N-D molecules presented only conductor property. The compound with nitrophenyl substitution resulted in a higher ON/OFF current ratio of 104, and the fluorophenyl substitution exhibited the lowest threshold voltage of -1.19 V. Solubility of the compounds in common organic solvents suggests that they are promising candidates for economic solution-processable techniques. Density functional theory calculations were used to envision the frontier molecular orbitals and to support the proposed resistive switching mechanisms. It is inferred that the presence of donor/acceptor substituents has a significant impact on the highest occupied molecular orbital-lowest unoccupied molecular orbital energy levels of the molecules, which affects their memory-switching behavior and thus suggests that a D-A architecture is ideal for memory device resistance switching characteristics.

Automated summary

In order to comprehend the relationship between structure and property as well as the significance of the donor-acceptor system in resistive memory devices, a series of new organic small molecules were designed and synthesized. The devices with A-N-D-N-A structures exhibited write-once-read-many memory behavior, while those based on D-N-D-N-D molecules only showed conductor property. The presence of donor/acceptor substituents significantly influenced the memory-switching behavior, suggesting that a D-A architecture is ideal for resistance switching characteristics in memory devices.