Luminescent gold-poly(thiophene) nanoaggregates prepared by one-step oxidative polymerization

We report the facile synthesis, formation mechanism, and photoluminescent (PL) properties of gold-poly(thiophene) (Au-PTh) nanoaggregates. They were prepared by one-step oxidative polymerization, in which Au³⁺ ion was utilized as an oxidizing agent for the polymerization of thiophene. Transmission electron microscopy (TEM) and high-resolution TEM (HR-TEM) analyses demonstrated that the 'raspberry-like' Au-PTh nanoaggregates consist of individual Au NPs covered by PTh and stabilized by Tween 80. For Au-PTh nanoaggregates, a clear red shift in the SP peak was observed in the UV absorption spectra as compared with pristine Au nanoparticles (NPs). This red shift of the SP band is a consequence of the location of π-conjugated PTh on the surface of Au NPs, resulted from a strong binding between sulfur atoms of PTh and the Au NPs (sulfur-gold interaction). The strong interaction between the gold and sulfur atoms of PTh in the Au-PTh nanoaggregates was observed by X-ray photoelectron spectroscopy (XPS) analysis. The SP effect contributes to the PL intensity enhancement of the Au-PTh nanoaggregates and was confirmed by confocal laser scanning microscopy (CLSM).