Making graphene luminescent by adsorption of an amphiphilic europium complex

We fabricated luminescent chemical vapor deposition-grown monolayer graphene sheets with an adsorbed europium complex, EuLC₁₈, and characterized their luminescence properties. The EuLC₁₈/graphene sheets clearly showed several photoluminescence peaks in a wavelength region from 580 to 694 nm, which were attributed to the ff transitions of the Eu ion. Luminescence was obtained via a photo-antenna effect, in which the ligands of EuLC₁₈ absorbed the photo-excitation energy and transported it to the Eu excitation. Although the absolute luminescence quantum yield of the EuLC₁₈/graphene sheet was as low as 0.5% due to the interaction between graphene and EuLC₁₈, we demonstrated that graphene sheets can be made luminescent simply through adsorption of the luminescent Eu complex on the graphene surface.