Towards the Manipulation of Defects and Dopants to Functionalise Graphene - a DFT Based Study and Development of New Theoretical Methods

Abstract

Graphene is a material, which is exhibiting a rising research interest over the last few years due to its unique properties and various possible applications. Possible applications range from optical sensing and drug delivery up to fuel and solar cells as well as composite materials. Based on experimental findings, first principle theory of electronic structure calculations (DFT) shall be used to examine the effects of p/n-doping and defects on the material’s properties as to find a way of band gap tuning and to understand the underlying mechanisms of it. Not only graphene shall be examined in this context but also hexagonal Boron-Nitride Nanosheets (h-BNNs). Especially a radical functionalisation of h-BNNs with oxygen, nitrene and carbene is of interest. Based on DFT, IR spectra, Raman spectra and structural properties shall be computed and compared with experimental results. Density of States and Band structures shall be calculated as to understand the electronic properties of the examined materials. These results shall build the basis for working on further questions and to develop methods beyond DFT as to find a better description of the systems of interest. Further questions of interest are for example how the radicals adsorb on the h-BNNs, how magnetic impurities or the adsorption of magnetic materials change the properties of graphene or h-BNNs and how environmental effects influence the adsorption of different molecules on graphene. Methods describing dynamical correlations (e.g. Dynamic Mean Field Theory) are of interest in the context of working with strongly correlated materials. Furthermore, coarse grained methods offer a better description of dispersion forces and can be used to receive a better description of environmental effects. In this context, the development of double hybrid functionals may be of interest as well since they also tend to give a better description of dispersion forces. Another point of interest is the examination of charge transport properties with graphene-based electrodes, for example with methods based on the Landauer-formalism.