Charge dynamics on size confined conducting polymers through electron paramagnetic resonance spectroscopy

Abstract

Abstract A complete understanding of single electron behavior in mesoscopic conjugated polymers is necessary for the development of advanced organic light emitting diodes, spintronics, flexible electronics and bioelectronics. In this study, we investigate the charge dynamics of conjugated polymer nanowires (CPNWs), synthesized using polypyrrole (PPy) and poly (3, 4- ethylenedioxythiophene) (PEDOT) and having diameters of 100 and 200 nm. The electrical properties and magnetic behavior of charges at the localized doping sites are probed using temperature dependent I–V analysis and electron paramagnetic resonance (EPR) spectroscopy. The I–V curves indicate that the applied bias and the diameter of the CPNWs, as well as their crystallinity, are important factors for charge injection and transport along the polymer chain. The EPR experiments show a relative increase in the spin relaxation time of PPy whereas a corresponding decrease is observed for PEDOT, as the diameter decreases. Based on the experimental results, the size effect and the interaction between charge carriers within the one-dimensional conducting polymer are discussed considering the doping states. These results are expected to extend the understanding of electronic behaviors in mesoscopic conjugated polymers.