Altering the Position of Phenyl Substitution to Adjust Film Morphology and Memory Device Performance

In this study, two structural isomers α-PBT and β-PBT, which only differ in the phenyl substituent position on the quinoline chromophore, have been designed and successfully synthesized. The influences of substituent position on the film morphology and the storage performance of the devices were investigated. Both molecules employed in the memory devices exhibited same nonvolatile binary (write-once-read-many-times; WORM) characteristics, but the switch threshold voltage (Vth) of the β-PBT-based device was clearly lower than that of the α-PBT-based device. Simulation results demonstrate that the variation of the phenyl substituent position led to different intermolecular stacking styles and thus to varied grain sizes for each film morphology. This work illustrates that altering the phenyl substituent position on the molecular backbone could improve the quality of the film morphology and reduce power consumption, which is good for the rational design of future advanced organic memory devices (OMDs).