Synthesis and memory characteristics of novel soluble polyimides based on asymmetrical diamines containing carbazole

- Two diamines (BNBCD, CBMCD) and four novel soluble polyimides have been prepared.
- The resulting polymers were fully characterized by UV-vis, PL, TGA, CV, XRD, etc.
- PI-a, PI-b and PI-c showed flash type memory traits, PI-d showed a WORM type.

Two novel asymmetrical carbazole-based diamines 9-(2-(1,1′-binaphthyl-4-yl)benzyl)-9H-carbazole-3,6-diamine (BNBCD) and 9-((4′-(9H-carbazol-9-yl)biphenyl-2-yl)methyl-9H-carbazole-3,6-diamine (CBMCD) were synthesized. A series of novel soluble aromatic polyimides were prepared from these diamines by poly-condensation with Pyromelitic dianhydride (PMDA) and 2,2′,3,3′-biphenyl tetracarboxylic dianhydride (BPDA) via a two-step procedure. The resulting polymers were fully characterized, they exhibited excellent organosolubility and high thermal stability with the temperature of 5% weight loss under nitrogen atmosphere over 400 °C. Resistive switching devices with the configuration of Al/polymer/ITO were constructed from these polyimides by using conventional solution coating process. The memory devices based on PI-a, PI-b and PI-c exhibited a flash type memory capability, whereas the PI-d presented a write once read many times (WORM) memory capability.

Four novel soluble carbazole-containing polyimides were prepared from BNBCD and CBMCD by poly-condensation with Pyromelitic dianhydride (PMDA) and 2,2′,3,3′-biphenyl tetracarboxylic dianhydride (BPDA) via a two-step procedure. The PI-based devices exhibited flash type memory behaviors and WORM memory character.