Synthesis and memory properties of a series of novel asymmetric soluble polyimides

Two asymmetric diamines [1,1′-biphenyl]-4-yl(3,5-diaminophenyl) methanone (BPDAM) and (3,5-diaminophenyl)(4′-(naphthalen-1-yl)-[1,1′-biphenyl]-4-yl) methanone(DANPBPM) were synthesized by Suzuki coupling reaction from (4-bromophenyl)(3,5-diaminophenyl) methanone (BDAM) and corresponding arylboronic acid. A series of polyimides exhibiting organic solubility were prepared from 2,2′,3,3′-biphenyl tetracarboxylic dianhydride(BPDA) and these above three new diamines via a two-stage process. The obtained polymers showed outstanding organic solubility and high thermal stability. And studies have shown that the storage device with a sandwich type configuration of Al/polyimide/ITO was prepared by the traditional liquid spin coating technology, which showed the storage capacity of flash memory type. All the polyimide-based devices showed bistable conductivity switching and nonvolatile memory behavior that had long preservation period and high ON/OFF electric current, the rate of which was 104.

Effect of a "Zn Bridge" on the Consecutively Tunable Retention Characteristics of Volatile Random Access Memory Materials

Polyimide memory materials with a donor-acceptor structure based on a charge-transfer mechanism exhibit great potential for next-generation information storage technology due to their outstanding high-temperature resistance and good dimensional and chemical stability. Precisely controlling memory performance by limited chemical decoration is one of core challenges in this field. Most reported work mainly focuses on designing novel and elaborate electron donors or acceptors for the expected memory behavior of polyimides; this takes a lot of time and is not always efficacious. Herein, we report a series of porphyrinated copolyimides coPI-Znx (x=5, 10, 20, 50, 80), where x represents the mole percentage of Zn ion in the central core of the porphyrin. Experimental and theoretical analysis indicate that the Zn ion could play a vital bridge role in promoting the formation and stabilization of a charge-transfer complex by enhancing the hybridization of local and charge transfer (HLCT) excitations of porphyrinated polyimides, endowing coPI-Znx with volatile random access memory performance and continuously tunable retention time. This work could provide one simple strategy to precisely regulate memory performance merely by altering the metal content in porphyrinated polyimides.