Structural and optical characteristics of charge transfer complex of plasma deposited 2-(diethylamino)ethyl methacrylate thin films and iodine

Abstract

The effect of iodine doping on the optical and structural characteristics of plasma polymerized 2-(diethylamino)ethyl methacrylate (PPDEAEMA) thin films are described in this paper. Scanning electron micrographs show that both as-deposited and iodine doped PPDEAEMA thin films are homogeneous. Thermogravimetric analysis demonstrates the stability temperature as 560 K for iodine doped PPDEAEMA. The degradation temperature of iodine doped PPDEAEMA is slightly greater than that of as deposited PPDEAEMA. Fourier transform infrared spectroscopy shows shifts in absorption bands due to the incorporation of iodine in PPDEAEMA. The absorption coefficient and allowed direct and indirect transition energy gaps were calculated from the ultraviolet–visible absorbance spectra. The energy band gap value decreases due to iodine doping. Urbach energy, steepness parameter and extinction coefficient were calculated as well for the PPDEAEMA thin films of thicknesses 100, 200 and 300 nm which were iodine doped for 45, 360 and 720 min.