Enhanced Polaron Delocalization in Phytic Acid-Doped Polyaniline Nanofibers

Polyaniline is a widely used conducting polymer because of its facile synthesis and unique optical and electrochemical properties. It has been demonstrated that protonation of polyaniline increases its conductivity by inducing the formation of polarons along the polymer backbone. These polarons are responsible for charge transport through the conjugated system. In this work, we investigate the impact of phytic acid (PA) doping on the electronic properties of polyaniline (PANi) synthesized via the oxidative polymerization method. The photophysical properties were studied using ultrafast transient absorption spectroscopy (TAS). Compared to undoped PANi, phytic acid-doped polyaniline (PA/PANi) exhibits enhanced charge carrier delocalization and prolonged polaron lifetimes, which indicates improved charge transport dynamics. The photophysical behavior observed at 300, 400, and 600 nm pump wavelengths shows the significant spectral changes that are attributed to protonation and cross-linking between PA and PANi. This enhanced charge carrier mobility is due to the formation of a three-dimensional (3D) interconnected mesh-like nanofiber structure upon PA doping. These findings provide insights into how molecular-level doping can be used to tune charge transport properties in conducting polymers, with potential applications for the design of advanced organic electronic and energy storage devices.