“We were really excited to discover this: when two UV absorbing materials, namely TiO2 and graphene quantum dots, were mixed together, they started to absorb in the visible range. More significantly, the bandgap can be tuned by the size of graphene quantum dots,” said Dr Li, associate professor in the Environmental Engineering and Queensland Micro- and Nanotechnology Centre. “We named the phenomenon ‘quantum-confined bandgap narrowing’ and this mechanism may be applicable to all semiconductors, when they are linked with graphene quantum dots. Flexible tuning of bandgap is extremely desirable in semiconductor-based devices.”
Such a mechanism may allow the design of a new class of composite materials for light harvesting and optoelectronics.