Graphene-Based Hybrid Materials Incorporating Multichromophores

Abstract

Hybrid materials based on graphene have the potential to drive a variety of nanotechnological applications ranging from optoelectronics, to biomedical, as well as, industrial. Herein, we present an array of novel graphene-based materials incorporating one or more chromophore systems, anchored onto graphene through covalent or non-covalent interactions, targeted for energy conversion schemes.Graphene single- and/or few-layered graphene sheets have been prepared through ultrasonication processes, introducing minimal defects onto the graphitic backbone while affording comparatively large quantities to allow for chemical modification.1 The chromophores selected to form hybrid graphene nanoensembles, through covalent bond formation, range from pyrene, porphyrin and oligo-thiophene adducts.2 The resulting hybrids afforded stable suspensions in a variety of common organic solvents and allowed for detailed characterization in liquid phase. In addition, non-covalently formed graphene-based nanoensembles were also prepared and the various systems comprised of thiophene chromophores, but also pyrene-porphyrin and dual porphyrin systems.2 All synthesized hybrids have been extensively characterized with thermogravimetric analysis, microRAMAN, and optical techniques (absorption, steady state and time-resolved photoluminescence spectroscopy) among others to verify, the structural and optoelectronic properties of the nanoensembles. Also due to the increased solubility of the hybrids and the ability to form stable suspensions, electrochemistry was used to elucidate the energy levels of the chromophores, as well as the resulting hybrids, affording insight on the thermodynamically favored mechanisms in the system. Finally, time-resolved photoluminescence experiments verify the promotion of electronic communication of the chromophores with the graphene substrate.Financial support from GSRT/NSRF 2007-2013 through action “Supporting Postdoctoral Researchers” project GRAPHCELL PE5(2126) is acknowledged.ReferencesS. P. Economopoulos, N. Tagmatarchis, Chem. Eur. J. 2013, 19, 12930.S. P. Economopoulos, N. Tagmatarchis, Manuscript in preparation, 2014.