Tristable Memory Devices Based on Soluble Polyimides Containing Pendant Carbazole and Phenyl Groups

As an important component of highly functional macromolecule semiconductor, two kinds of new diamine monomers, bis(5-amino-6-methoxy-[1,1'-biphenyl]-3-yl) methanone (BAMBPM) and bis(5-amino-4'-(9H-carbazol-9-yl)-6-methoxy-[1,1'-biphenyl]-3-yl) methanone (BACzMBPM) were used as raw materials. Two kinds of soluble aromatic polyimides were prepared from BAMBPM and BACzMBPM by polycondensation with 2,2',3,3'-biphenyl tetracarboxylic dianhydride (BPDA) via a two-step procedure. The obtained polyimides were sufficiently characterized, and showed superior organic solubility and excellent thermal stability, with a weight loss of 5 % weight loss above 300 degrees C. Memory devices with Al/polyimide/ITO structure were prepared by the traditional method of solution spin coating. Both devices show tristable characteristics, with high ON/OFF current ratios as high as 10(4) and long maintenance times of 10(4) seconds in the environmental atmosphere.