Preparation, characterization and electronic and optical properties of plasma-polymerized nitriles

Conjugated polymers are among the most promising organic materials for optoelectronic devices. In such applications, the main fabrication challenge is to get uniform, defect-free and reproducible thin films of these materials. In this research, a series of novel plasma-polymerized 4-cyanopyridine (PPCPD) thin films of desired thickness were prepared through plasma polymerization under different glow discharge conditions. They were transparent, pinhole-free and uniform. The effect of the discharge power on the chemical structure and surface compositions of the plasma-polymerized 4-cyanopyridine (PPCPD) films was investigated by Fourier transform infrared (FTIR), UV-visible absorption spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS) and the deposition rate measurements. A high retention of the aromatic ring structure of the starting monomer in the deposited plasma films is obtained when a low discharge power of 3 to 10 W was used during film formation. A red shift in the maximum absorption wavelength (λ_max) for all the plasma-deposited films was observed as compared with the monomer absorption spectrum. The atomic force microscopy (AFM) measurement shows that the PPCPD film with quite smooth surface could be grown under a relatively low discharge power.