Optical and Morphological Properties of Electropolymerized Semiconductor Polyaniline Thin Films: Effect of Thickness

Electronic conductive polymers have aroused considerable research interest for their possible use in different technologically relevant applications, such as modified electrodes for electrocatalysis, energy storage devices, corrosion and sensors. Thin films of polyaniline (PAni) have been deposited on indium tin oxide substrate by electropolymerization using cyclic voltammetry. The thickness of thin films has been varied between 0.1 mu m and 7 mu m by controlling the number of cycles. The deposited thin films were characterized to investigate the morphological and optical properties with scanning electron microscopy (SEM), photoluminescence spectroscopy, UV-Vis spectroscopy and electrochemical spectroscopy impedance. The SEM micrographs revealed that the thin films possess porous structure with an assembly of numerous fibers. The morphology of thin films observed to vary with the number of cycles during the electropolymerization of aniline. Photoluminescence spectra show a broad peak around 373 nm due to inter-band transition between polaronic and pi bands. The optical band gap value was observed to vary from 2.58 eV to 2.31 eV as a function of film thickness.