Regulating the electrical resistive switching behaviors of polyimides through different steric hindrance substituents on 2,7-position of tetraphenyl fluorene diamines moieties

Three novel polyimides (PI(TPF-Br BPDA), PI(TPF-Ph BPDA), and PI(TPF-Ph-OMe BPDA)) with tetraphenyl fluorene (TPF) were synthesized and tested. The laboratorial results showed that the constructed electronic devices exhibited different memory behaviors due to the different steric hindrance substituents (bromine atom, phenyl, and 3,5-dimethoxyphenyl) in 2,7-position of TPF molecule. The memorizers based on PI(TPF-Br BPDA) and PI(TPF-Ph BPDA) presented volatile dynamic random access memory (DRAM) feature with turn-on voltages of −2.39 and +1.45 V, as same as −1.71 and +1.74 V, separately. However, the PI(TPF-Ph-OMe BPDA) based apparatus exhibited non-volatile write-once read-many-times memory (WORM) behavior with turn-on voltage of −1.13 V, due to the more charge traps of 3,5-dimethoxyphenyl moieties and higher dipole moment. The switching mechanism was verified by quantum simulation of energy level, electrostatic potential (ESP) surface and dipole moment. These results indicated that the electrical memory performance of the synthesized TPF-based PIs could be adjusted by modifying the electron donor structure.

Flexible Multifunctional Aromatic Polyimide Film: Highly Efficient Photoluminescence, Resistive Switching Characteristic, and Electroluminescence

We report a flexible multifunctional aromatic polyimide (BTDBPI) that shows yellow-green fluorescence with high photoluminescence quantum yield (PLQY) of 30% in the film state. The nonvolatile "write once-read many" (WORM) characteristic in a memory device with the configuration of ITO/BTDBPI/Au indicates that BTDBPI possesses organic semiconductor behavior. Moreover, polymer light-emitting diodes (PLEDs) with the structure of ITO/PEDOT:PSS/BTDBPI/TPBI/Mg-Ag exhibits an interesting dual-emission phenomenon that originates from the electroluminescence (EL) of the BTDBPI nanometer film (yellow-green, 525 nm) and TPBI (deep blue, 380 nm), demonstrating that BTDBPI shows both the charge-transporting and EL properties.

Synthesis and non-volatile electrical memory characteristics of triphenylamine-based polyimides with flexibility segments

Two triphenylamine-based polyimides (PI(TPA-PMDA) and PI(TPA-BPDA)) containing a flexibility segments were prepared. The memory device of ITO/PI(TPA-PMDA)/Al exhibited write-once read-many-times (WORM) memory behavior, however, the memory device of PI(TPA-BPDA) demonstrated flash-type memory characteristics.