Chemistry Approach towards Graphene Nanoribbons with Defined Shape and Edge Structures

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Graphene as a two-dimensional atomic carbon monolayer has received tremendous attention in recent years, however, there is still a lack of methods to produce graphene sheets on insulating surfaces and graphene nanoribbons with reproducible defined shape and edge structures to obtain tailor made semiconductor properties. Within the present priority program, we are going to address especially these two issues from the chemical point of view. For the bottom-up synthetic approach towards graphene production on surfaces we will transfer our huge experience in solution based chemistry for the production of well defined giant polycyclic aromatic hydrocarbons (PAHs) into the requirements for surface chemistry. We propose a chemical route which is based upon the intramolecular cyclodehydrogenation (“graphitization”) of well-defined dendritic (3D) polyphenylene precursors in solution and on the surfaces. Especially for the production of graphene nanoribbons this approach is in stark contrast to other physical and chemical methods of graphene formation in terms of its (i) size and shape control (ii) structural perfection and (iii) processability (solution, melt, even gas phase). This bottom-up approach can further establish the link to graphene through the simple thermolysis of nanographene molecules on the surfaces. Beyond this, the chemical approach allows to attach anchor groups with high metal affinity at the both ribbon ends to enable self aligning between electrodes in principle. If this concept can be established, wide applications of graphene nanoribbons in electronic devices and material sciences should be possible in future.