Preparation of Propiolic Acid Doped Polyaniline and Investigation of Opto-electronic Properties

Abstract

Among the conducting polymers, polyaniline is of vital importance as an electronic material [1, 2, 3, 4] because of its easy synthesis, environmental stability, reversible proton dopability, redox recyclability, cost-effectiveness, and reasonable electrical conductivity. Electrical and optoelectronic applications of conducting polymers often require high current densities that can be achieved by either heavy doping or a high-level carrier injection. Polyaniline occurs in four oxidation states (i.e., leucoemeraldine, emeraldine base, emeraldine salt, and pernigraniline), out of which only emeraldine salt is conductive in nature (the others are insulating in nature). Polyaniline (PANI) exists in a variety of forms that differ in chemical and physical properties [5, 6, 7, 8, 9]. Polyaniline is one of the most promising conducting materials for applications in optoelectronics and microelectronics devices. The doping of polyaniline can be accomplished through protonic acid and oxidative doping. Protonic acid doping of emeraldine base units results in complete protonation of imine nitrogen atoms to give the fully protonated emeraldine salt [10, 11]. The AC (alternative current) conductivity properties of Polyaniline (PANI) and doped PANI parallel plate materials were investigated by impedance spectroscopy. The real part of conductivity (sigma '), and the real part of impedance (Z(p)(')) were measured in the logarithmic frequency range of 100 to 1.5x10(7) Hz at 25, 40, 50 and 100 degrees C temperatures. The AC conductivity value of the undoped PANI is high values for polymeric materals to ionic conduction and electrode polarization in low frequency. The alternative current (AC) conductivity increases with increasing MB concentration and the frequency.