Optical properties of electrochemically synthesized polypyrrole thin films: the electrolyte effect

Polypyrrole thin films are prepared by the potentiostatic mode of electrodeposition at +0.7 V versus a saturated calomel electrode (SCE). The polypyrrole films are prepared in the presence of different electrolytes such as:p-toluene sulphonic acid (PTS), oxalic acid and H 2 SO 4 . The prepared films are characterized by UV-vis absorption spectroscopy and normal reflectance measurements. The electrochemically synthesized films are semiconductor in nature. The band gap energy of polypyrrole thin films is found to be 1.95, 1.92 and 1.79 eV for H 2 SO 4 , oxalic acid and p-toluene sulphonic acid, respectively. The normal reflectance spectroscopy of polypyrrole films shows that the maximum reflectance is in the presence of p-toluene sulphonic acid; this is may be due to a more distinct microstructure than the others. The optical constants such as the extinction coefficient, refractive index, optical conductivity, etc. are calculated and studied with various electrolytes.