Electropolymerization of polyaniline thin films

Abstract

Polyaniline (PANI) thin films have been electrochemically synthesized onto conducting glass substrates. The current study demonstrates that the properties of PANI films depend on the concentration of dopant acid. Well-adherent PANI coatings were obtained under potentiodynamic conditions during sequential scanning of the potential region between −0.35 V and +1.7 V with respect to silver/silver chloride. The structural, optical, and morphological properties of PANI films were studied with the aid of X-ray diffraction (XRD), Raman spectroscopy, ultraviolet–visible (UV-Vis) absorption spectroscopy, photoluminescence (PL) spectroscopy, and field-emission scanning electron microscopy (FESEM). Current–voltage (I-V) measurements were performed to study the electrical properties of PANI films. The XRD peaks observed at 2θ = 15.4°, 24.2°, and 25.1° confirm the synthesis of emeraldine form of PANI. The strong absorption peaks observed in the UV-Vis absorption spectra at 317 nm (π–π* interband transition), 371–427 nm (polaron band transition), and 750 nm (bipolaron band transition) confirm the formation of emeraldine oxidation state of PANI. A broad peak attributed in the PL spectra around 395 nm is related to the transition from polaronic band to the π band. All the intense bands attributed in the Raman spectra are associated with the emeraldine oxidation state of PANI. FESEM images reveal the formation of fibers and belts of PANI. Highly conducting thin films of PANI deposited at higher concentrations of dopant acid were confirmed by I-V measurements.