**5. Summary and conclusions**

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‐ led by light.
