RAMAN SPECTROSCOPY AND PHOTOLUMINESCENCE CHARACTERIZATION OF THE IODINE DOPED PLASMAPOLYMERIZED BIPHENYL THIN FILM

The iodine doped plasma-polymerized biphenyl thin film is investigated inthis study. Iodine atoms lead to increase the charge transfer complexes and change theelectronic equilibrium in the polymer structure due to their high electronegativity. Therefore,the iodine doped films show significant improvements in the electrical characteristics ascompared to the undoped ones. The results of Raman spectroscopy verify the presence of theiodined groups in the structure of deposited thin films. The number density of the iodinedgroups increases with increasing the radio frequency input power. The ID/IG ratio changes ina range from 0.40 to 0.72 for the undoped thin films while it decreases from 0.74 to 0.58 forthe iodine doped thin films which can be due to the rearrangement in the structure.Photoluminescence spectra show a broad red emission band at about 630 nm as well asunclear bands placed like small shoulders at 580 nm and 731 nm. These bands become toseem clearly after the iodine doping process. The conjugation length of the polymer thin filmsincreases with iodine doping as well as increasing the power values. All depositions areproduced using a capacitively coupled plasma system with 13.56 MHz radio frequencysource. During the doping process, the vaporized iodine material is directly exposed to theplasma discharge and mixed with the biphenyl polymer material. All results are characterizedin detail.