Solution-processable graphene quantum dots

Graphene is a new addition to the family of carbon materials and is made of a single layer of carbon atoms packed in a honeycomb lattice. Graphene has many unique properties and great potentials for various applications. Among these fascinating properties, the size-dependent band gap and the large absorptivity are particularly interesting for light harvesting in photovoltaics.;We have developed a novel solubilizing strategy to prevent the aggregation of graphene quantum dots (QDs), i.e. nanosized graphenes. This enables us to synthesize highly soluble graphene QDs using well-developed carbon chemistry, so that we can make high-quality graphene QDs with uniformed size, precisely tailored geometry and functionalization. With this effective strategy, we have successfully synthesized graphene QDs with different sizes, shapes, and functionalization. Our studies show that bandgaps and redox potentials of the graphene QDs can be independently tuned, the former by size and the latter by functionalization. We have used these graphene QDs as light absorbers in dye-sensitized solar cells.