To better understand the structure-property relationships, two novel aromatic diamines containing tetraphenyl fluorene (TPF) moiety through triphenylamine (TPA) unit and carbazole (Cz) unit modification are designed and synthesized, respectively. Four thermally stable and excellent solubility polyimides are prepared and characterized. The excellent film-formation ability and thin film stability are investigated by X-ray diffraction (XRD) and atom force microscopy (AFM) measurements, respectively. The memory devices are fabricated, PIs films with low water uptakes sandwiched between indium-tin oxide (ITO) ground electrode and Al top electrode, and exhibit nonvolatile write-once read-many-times (WORM) memory behaviors with low threshold voltages, due to increasing the retention time through regulating the energy level. The current conduction mechanisms of all devices are linearly fitted by theoretical conduction model. Molecular simulations are used to demonstrate switching mechanism and the memory effects. The experimental results provide a sight for the design-adjustable switching voltage of memory devices. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1630-1644