Characterization and modification of optical properties of graphene oxide and reduced graphene oxide

Abstract

In this work, we focus on finding controlled methods to tune the optical properties of reduced graphene oxide (RGO) and graphene oxide (GO). This is accomplished by ozone treatment transforming RGO into GO or altering electronic properties of GO. This approach can yield drastic color (visible absorption) change and controlled increase in fluorescence intensity, optical band gap, fluorescence lifetime, and quantum yield. A reverse process: controllable quenching of this fluorescence is achieved by thermal treatment of GO. We attribute observed optical changes to the introduction/rearrangement of oxygen-containing functional groups on the graphitic platform. Following this scenario, we model the band structure of GO subject to ozone treatment via semi-empirical PM3 calculations, which, supported by our experimental data, helps in describing the origins of GO emission. This work also shows the feasibility of ozone and thermal treatments for controllable variation of GO optical properties desirable for a variety of applications in optoelectronics and biomedicine.