Synthesis and optical characterization of acid-doped polyaniline thin films
Polyaniline has attracted much interest among researchers because of its reasonably good conductivity, stability, ease of preparation, affordability and redox properties compared to other organic compounds. In this work, Polyaniline (PANI) thin films were synthesized by chemical oxidative polymerization of aniline in the presence of Hydrochloric acidusing Ammonium peroxydisulfate as an oxidizing agent. The synthesised PANI thin films, doped with Tetraoxosulphate VI acid ( H2SO4) and Citric acid, were characterised using UV - Vis spectroscopy to investigate the variations in the optical properties. The thin films were found to be of the same thickness (0.2 µm) and their absorption spectra revealed two absorption peaks at around 300nm and 650nm for the pure PANI and the sample doped with Citric acid while that doped with H2SO4 had its peaks at 300 nm and 880nm. Doping reduced the direct band gap of the PANI from 2.75eV to 2.4eV.
Keywords: polyaniline thin film,organic compounds, chemical oxidant polymerization synthesized polyaniline, optical properties