Characterization and film forming application of polythiophene nanoparticles synthesized by Fe ³⁺-Catalyzed oxidative polymerization in aqueous medium

Polythiophene (PT) nanoparticles having different particle size were prepared by Fe ³⁺-catalyzed oxidative polymerization in aqueous medium. They were characterized by UV-vis spectroscopy, photoluminescence (PL) spectroscopy, scanning electron microscope (SEM), and transmission electron microscope (TEM). As the concentration of surfactant, i.e., polystyrene sulfonate (PSS), increased, the particle size of PT nanoparticles decreased from 52 nm to 20 nm. This was confirmed by SEM analysis. The increase of PL intensity was observed with the decrease of particle size of PT nanoparticles. This resulted from the increased total surface area of PT nanoparticles due to the particle size reduction. Furthermore, self-absorption effect also became weak as the particle size decreased. PT nanoparticles prepared by using PSS could be directly used to make film by annealing at 150 °C without any additional solvent casting procedure. This film showed the PL peak at 580 nm excitation wavelength. The resulting PT nanoparticles prepared by using PSS are potentially useful in fabricating high quality active layer for electroluminescence (EL) devices.