Comparative study of charge transfer between organic dye with graphene and its quantum dots

The absorption and photoluminescence spectra of fluorescein 27 (F27) in presence of graphene and graphene quantum dots (GQD) have been investigated quantitatively. The fluorescence intensity of F27-graphene hybrid system is reduced drastically as compared to free F27. In contrast, the GQDs enhance the luminescence by a factor of 1.5. The fluorescence quenching of F27-graphene hybrid system suggests a strong charge transfer (CT) from F27 to graphene. On the other hand, the fluorescence enhancement in case of GQD takes place due to the vdW type complex formation between GQD and F27. It is concluded here that while the F27-graphene, the CT complex is non-fluorescent in nature but with GQD a weak fluorescent complex formation takes place with a possibility of facilitating the energy transfer from the former to latter.