**Author details**

supported by the increase of total fluorescence intensity observed with increasing concentra‐ tion of PVA in solution. In fact, this increase is over an order of magnitude, although the

There is also another important aspect that must be considered when fabricating graphenebased hybrid nanostructures. An alternative approach to prepare layers of fluorophores on graphene substrates would be through spin coating of a solution of PCP complexes in PVA matrix. The obtained layers are much more uniform than those made by simple drop-casting, and it shows no systematic dependence on the PVA concentration. Rough estimations, based on the distribution of emission intensities measured as emission spectra or decay curves, suggest that the uniformity of the layers prepared with spin coating is about a factor of two better in terms of a standard deviation, as compared to the drop-casted samples. At the same time, the concentration of PCP complexes within the focal volume of the laser would dimin‐ ish considerably as compared with the drop-casting approach; thus, this parameter must be

Graphene and its derivative, reduced graphene oxide, are unique energy acceptors. While not exhibiting any fluorescence, both absorb energy in the whole visible spectral region with quite uniform efficiency. As such, graphene-based materials can be considered attractive plat‐ forms for light harvesting, energy conversion and biosensing. In this chapter, we described several experimental observations obtained for hybrid nanostructures composed of natural photosynthetic complex PCP and either graphene or reduced graphene oxide. Each studied structure sheds its own light on the mechanisms and processes that are taking place in such systems. We show that by controlling the composition of the solution and sample prepara‐ tion, it is possible to tune the efficiency of the energy transfer to graphene and thus deter‐ mine the sensitivity of energy transfer as a probing tool for interaction with graphene. The results obtained for PCP/rGO system indicate bimodal nature of the on-going interactions: in addition to commonly observed fluorescence quenching, we find pronounced and frequent events, where the emission of the PCP complexes is substantially enhanced. Last but not least, the uniqueness of graphene as energy acceptor manifests itself in a strong dependence of the energy transfer efficiency on the excitation wavelength. This observation allows drawing a completely new picture of the excitation dynamics, and the energy transfer, in systems where the properties of either acceptors or donors can be additionally and independently control‐

This research has been supported by the WELCOME project 'Hybrid Nanostructures as a Stepping Stone towards Efficient Artificial Photosynthesis' funded by the Foundation for

amount of the solution deposited on a substrate is in all cases identical.

carefully adjusted.

170 Recent Advances in Graphene Research

led by light.

**Acknowledgements**

**5. Summary and conclusions**

Sebastian Mackowski1,2\* and Izabela Kamińska1,3

\*Address all correspondence to: mackowski@fizyka.umk.pl

1 Optics of Hybrid Nanostructures Group, Faculty of Physics, Astronomy, and Informatics, Nicolaus Copernicus University, Torun, Poland

2 Baltic Institute of Technology, BalTech, Gdynia, Poland

3 NanoBioSciences, Institute of Physical and Theoretical Chemistry, TU Braunschweig, Braunschweig, Germany
