Photophysics of Graphene Quantum Dots and Their Composites

The emission from the GQDs consists of various complex processes. It is still a debatable topic, to discuss the origin of emission from the GQDs. There have been several attributions to the emission origin such as sp2 domains, free zigzag sites, and functional groups. Seeing a true intrinsic blue emission from colloidally synthesized GQDs is challenging because it is dominated by other emission components from functional molecules. Further graphene in its sheet form behaves like a metallic. The present chapter describes the photophysics of GQDs, and graphene sheet nanostructures with strong intrinsic blue emission characteristics through the formation of a composite. The incorporated zinc atoms have helped to interconnect the graphene QDs into a composite solid sheet, in such a way that graphene has all of the above-described properties. Since the composite graphene sheet structure has been found to exhibit strong blue emission, unlike metallic graphene sheets, this property was found to be due to the energy bandgap opened to nature.