Structural and dielectric properties of conjugated polynitrile thin films deposited by plasma polymerization

Plasma-polymerized 4-biphenylcarbonitrile (PPBPCN) thin films have been deposited by plasma polymerization technique. The effect of the discharge power on the chemical structure, surface composition and morphology of the PPBPCN thin films were investigated by Fourier transform infrared, UV–Visible absorption spectra, X-ray photoelectron spectroscopy, and atomic force microscopy. Structural and morphology characterizations show that a conjugated PPBPCN thin film with a high retention of the aromatic ring structure of the starting monomer can be deposited at a low discharge power. The plasma-synthesized film is homogeneous and quite suitable for the measurement of dielectric properties. The dielectric measurement shows that the dielectric constant of PPBPCN thin films decreased with frequency and increased with temperature.