Graphene Oxide Layer-by-Layer Films for Sensors and Devices

Layer-by-layer films of poly (allylamine hydrochloride) (PAH) and graphene oxide (GO) were characterized, looking at growth with the number of bilayers, morphology, and electrical properties. The PAH/GO films revealed a linear increase in absorbance with the increase in the number of deposited bilayers, allowing the determination that 10.7 +/- 0.1 mg m(-2) of GO is adsorbed per unit of area of each bilayer. GO absorption bands at 146, 210, 247 and 299 nm, assigned to pi-pi* and n-pi* transitions in the aromatic ring (phenol) and of the carboxylic group, respectively, were characterized by vacuum ultraviolet spectroscopy. The morphological characterization of these films demonstrated that they are not completely uniform, with a bilayer thickness of 10.5 +/- 0.7 nm. This study also revealed that the films are composed of GO and/or PAH/GO fibers and that GO is completely adsorbed on top of PAH. The electrical properties of the films reveal that PAH/GO films present a semiconductor behavior. In addition, a slight decrease in conduction was observed when films were prepared in the presence of visible light, likely due to the presence of oxygen and moisture that contributes to the damage of GO molecules.

Automated summary

Characterization of layer-by-layer films of poly (allylamine hydrochloride) (PAH) and graphene oxide (GO) revealed an increase in absorbance with the number of deposited bilayers, identifying the adsorption of GO per unit area of each bilayer. The films were found to be composed of GO and/or PAH/GO fibers, with GO completely adsorbed on top of PAH, exhibiting semiconductor behavior. Electrical properties indicated a slight decrease in conduction in the presence of visible light, possibly due to oxygen and moisture-induced damage to GO molecules.