Polyelectrolytes-assisted layer-by-layer assemblies of graphene oxide and dye on glass substrate

Abstract

Pyronin Y (PyY) and graphene oxide (GO) were assembled on a glass substrate by the electrostatic layer-by-layer (LbL) method with the assistance of polyelectrolytes. Firstly, the glass surface was modified with the successive adsorption of positively charged PEI (polyethylenimine) and negatively charged PSS (poly(sodium-p-styrenesulfonate)) to enhance the loading of PyY molecules and GO sheets. Secondly, PyY molecules and GO sheets were loaded on the glass substrate depending on their charges after the successive adsorption of polyelectrolyte layers via a procedure of {PEI/GO/PEI/PSS/PyY/PSS}_n. Thus, the LbL thin films containing PyY molecules and GO sheets, which remained stable for months, were homogeneously coated on the glass substrate. The photophysical and morphological features of the LbL films were examined. The spectroscopic data of the LbL films based on PyY revealed that H-aggregate and monomers structures of the dye molecules in the LbL films were formed by a function of the number of layers. Furthermore, the effect of immersion time on the molecular interaction of PyY molecules with the other components were studied in detail. SEM (scanning electron microscope) was used to examine the morphologies of as-prepared LbL thin films. SEM images revealed that the morphologies of LbL thin films were changed by the immersion time and the number of layers.