Changes in the optical properties of as-deposited plasma polymerized 2,6-diethylaniline thin films by iodine doping

• Optical properties of iodine-doped plasma polymerized 2,6-diethylaniline thin films.
• The surface morphology was smoother after iodine doping.
• Iodine doping significantly decreased the optical energy gap.
• The optical parameters changed according to the iodine doping period.

In this study, plasma polymerized 2, 6-diethylaniline (PPDEA) thin films of different thicknesses were synthesized using a glow discharge plasma polymerization method. Scanning electron microscopy showed that the surface morphology of an as-deposited PPDEA thin film was comparatively smooth after iodine doping. The iodine-doped PPDEA was found to be thermally stable up to ca about 560 K, which was slightly lower than that observed for as-deposited PPDEA. Ultraviolet-visible spectroscopic analyses demonstrated that iodine doping resulted in a significant decrease in the optical energy gap. As the doping period increased, the direct optical transition energy gap was reduced from 3.56 to 2.79 eV and the indirect optical transition energy gap was decreased from 2.23 to 1.97 eV. Thus it is observed that, the optical parameters of as-deposited PPDEA thin films with different thicknesses can be modified with different iodine doping periods.