Optical properties of functionalized graphene

Hybrid nanostructures are an emerging field in current research. The goal is to tailor material systems with desired electronic or optical properties by functionalization with molecules. Based on the density matrix formalism, we present a theoretical study on the optical properties of graphene functionalized with photoactive spiropyran molecules. Our calculations reveal the impact of the functionalization conditions on the absorption spectrum of graphene-based hybrid nanostructures. In particular, we find that the molecular coverage has a significant effect on the optical transition energy and shape, while the molecular dipole orientation plays a minor role.

The external molecular dipole field induces changes in the optical properties of graphene. Inset: The photoactive spiropyran molecules can be optically switched into the merocyanine configuration that is characterized by a pronounced dipole moment [after Guo et al., J. Am. Chem. Soc. 127(43), 15045 (2005)].