Ternary memory property of novel polyimide with backbone carbazole moiety and pendant triphenylamine moiety

The polyimide (TPA-Cz PI) was synthesized by the reaction of 9-(4 '-(4 '-diphenylamino)phenylbenzyl)-3,6-diaminocarbazole with 2,2 ',3,3 '-biphenyltetracarboxylic dianhydride through a classical two-step polymerization process. It exhibited excellent organo-solubility and self-extinguishing property. The synthesized TPA-Cz PI shown excellent film formation. The TPA-Cz PI film sandwiched between an indium tin oxide bottom electrode and Al top electrode. And the fabricated memory device exhibited ternary rewritable storage property in the bias with good data retention and the current ratio of 10(4):10(2):1 for ON2, ON1, and OFF states. Its current conduction mechanism by the I-V curves of different conduction models based on the experimental data was analyzed and used to illuminate the physical nature of resistance switching effects. The experimental result indicates that field-induced conformational ordering of the TPA-Cz PI chains and charge-transfer interaction between electron-donor and electron-withdrawing are responsible for the switching behavior. This work can provide a sketch for the design and selection of ternary state resistance random access memory materials in future research.