Structural characterizations and electrical properties of pyrolyzed polyimide containing silicon in the main chain

An insulating silicon-containing polyimide (SiDA-BDA), derived from polycondensation of bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride and benzidine, was converted into a conducting material after pyrolysis at 800–1000 °C in a nitrogen atmosphere. The maximum room temperature conductivity (σRT) of about 68 S cm−1 was obtained for SiDA-BDA film pyrolyzed at 1000 °C for 1 h. X-ray photoelectron spectroscopy (XPS) studies showed that the nitrogen atoms tended to evaporate quickly at pyrolysis temperature (Tp) higher than 800 °C while the silicon atoms tended to form silicon carbides and silicon oxycarbides as the pyrolysis temperature increased. The conducting behavior of the pyrolyzed SiDA-BDA films is in some ways typical of semiconductors while in other ways it is typical of conductors and can be described by a modified Mott’s 3D variable-range hopping (3D VRH) model.