Perylenediimide-Graphene Donor-Acceptor Nanoensembles: Synthesis, Characterization and Photophysics

Graphene is an outstanding material, consisting of a two-dimensional (2D) single layer of sp²-hybridized carbon atoms bonded together in a hexagonal “honeycomb” lattice and presents remarkable electronic and mechanical properties, like quantum hall effect at room temperature, an ambipolar effect along with ballistic conduction of charge carriers, tunable bandgap and high elasticity.¹ These exceptional properties of graphene make it an ideal candidate in construction of transparent conducting electrodes that could be used in energy conversion and storage systems. However, the preparation of high quality few-layered graphene materials is still an issue that must be circumvented and solvent assisted exfoliation using flat aromatic organic molecules as exfoliating assistants reveals as an extraordinary tool for that purpose.²

Herein, we present the liquid exfoliation of graphite to few layered graphene sheets together with the non-covalent supramolecular functionalization of exfoliated graphene sheets by the custom synthesized 1-N-methylpiperazinyl-N,N’-di(2-ethylhexyl)-perylene-3,4,9,10-tetracarboxydiimide (Pip-PDI).³ The planar aromatic Pip-PDI has the ability to non-covalently interact with exfoliated graphene sheets, stabilizing them and preventing their reassembly. On the other hand, the presence of the piperazine moiety on the bay position of the PDI core in the Pip-PDI makes it an ideal electron donor, nicely coupled with electron accepting exfoliated graphene, hence forming a novel donor-acceptor nanoensemble. The new PDI-graphene ensemble was characterized by complementary spectroscopic and microscopy techniques. Furthermore, electronic communication between the counterparts of the PDI-graphene nanoensemble was identified and probed by photophysical and redox assays, while prototype photoelectrochemical cells were constructed and evaluated.

Financial support from GSRT/NSRF 2007-2013 through action “ARISTEIA ΙΙ” project FUNGRAPH (3150) and CTQ2011-26455 and Prometeo 2012/010 is acknowledged.

References

1. A. K. Geim, K. S. Novoselov, Nat. Mater. 2007, 6, 183.
2. S. P. Economopoulos, N. Tagmatarchis, Chem. Eur. J. 2013, 19, 12930.
3. N. Karousis, L. Martin-Gomis, K. Ohkubo, T. Hasobe, A. Sastre-Santos, S. Fukuzumi, N. Tagmatarchis, Manuscript in preparation, 2014.