Synthesis and resistive switching characteristics of polyimides derived from 2,7-aryl substituents tetraphenyl fluorene diamines

Four novel aromatic diamines containing tetraphenyl fluorene (TPF) moiety were synthesized via a Suzuki coupling reaction. Then the four corresponding functional polyimides (PI(TPF-Ph), PI(TPF-Ph-Na), PI(TPF-2Na), and PI(TPF-Ph-OMe)) were prepared. The devices of PI(TPF-Ph) and PI(TPF-Ph-Na) displayed volatile DRAM behaviors with turn-on voltages of −1.80 and +1.62 V, as well as −1.34 and +1.36 V, respectively. The PI(TPF-2Na)-based device showed volatile SRAM behavior with turn-on voltages of −1.39 and +1.45 V. However, the PI(TPF-Ph-OMe)-based device exhibited non-volatile WORM behavior with turn-on voltage of −1.57 V. [Display omitted] •Four functional polyimides (PI(TPF-Ph), PI(TPF-Ph-Na), PI(TPF-2Na), and PI(TPF-Ph-OMe)) containing tetraphenyl fluorene (TPF) moiety and different substituent moieties were synthesized and characterized.•The memory devices of PI(TPF-Ph) and PI(TPF-Ph-Na) displayed volatile DRAM behaviors, however, the PI(TPF-2Na) device showed volatile SRAM behavior. And the PI(TPF-Ph-OMe) device exhibited non-volatile WORM behavior. Four new symmetric diamines (4,4′-(2,7-diphenyl-9H-fluorene-9,9-diyl)dianiline (TPF-Ph), 4,4′-(2,7-bis(4-(naphthalen-1-yl)phenyl)-9H-fluorene-9,9-diyl)dianiline (TPF-Ph-Na), 4,4′-(2,7-di([1,1′-binaphthalen]-4-yl)-9H-fluorene-9,9-diyl)dianiline (TPF-2Na), and 4,4′-(2,7-bis(3,5-dimethoxyphenyl)-9H-fluorene-9,9-diyl)dianiline (TPF-Ph-OMe)) containing tetraphenyl fluorene (TPF) core were synthesized through Suzuki coupling reaction, the corresponding four polyimides (PI(TPF-Ph), PI(TPF-Ph-Na), PI(TPF-2Na), and PI(TPF-Ph-OMe)) were prepared through polymerization reaction. The electrical memory measurement displayed that PI(TPF-Ph) and PI(TPF-Ph-Na) exhibited volatile dynamic random access memory (DRAM) behaviors, PI(TPF-2Na) possessed volatile static random access memory (SRAM) behavior due to the more distorted structure of 1,1′-binaphthalenyl moiety, and PI(TPF-Ph-OMe) showed non-volatile write-once read-many (WORM) behavior due to the presence of deeper charge traps and higher dipole moment of 3,5-dimethoxyphenyl substituent. They possessed low turn-on switching voltages and the ON/OFF current ratios were between 103 and 105 with the retention times up 4 × 103 s. Quantum simulations about energy levels, electrostatic potential (ESP) surfaces, and dipole moment were used to demonstrate the switching mechanism. The experimental results indicated that the electrical memory behaviors of the synthesized polyimides