Vacuum-deposited poly(p-phenylene) thin film and its structure, morphology and electronic properties

Poly(p-phenylene) (PPP) thin film was prepared by vacuum deposition from its parent powder PPP, and the structure, morphology and electronic properties have been studied by IR, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction and UV-Vis absorption spectroscopy. The IR spectrum gave evidence that the vapor-deposited PPP chain involves nine to ten p-phenylene rings. The SEM and AFM showed that the vacuum-deposited PPP film was composed of microcrystals of about 100 nm size with an amorphous part. The conductivity increased from 3.3 × 10−13 S/cm (non-doped) to 2.2 × 10−10 S/cm by iodine doping. A Schottky junction was formed between the PPP film and aluminum in a sandwich-type device.