Controlled Synthesis of Novel Functionalized Graphene Derivatives and Hybrid Structures

• Applicant: Professor Dr. Siegfried Eigler
• Subject Area: Solid State and Surface Chemistry, Material Synthesis
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 392444269

Carbon is unique and is the basis for life on earth. Many key-technologies, ranging from drug delivery to electronic applications, are based on carbon and make our modern civilization possible. Graphene has unique electronic properties and is outperforming conductive polymers by far. However, more important is the ability to functionalize the basal plane of graphene, an approach that allows introducing specific functions. We successfully introduced the controlled chemistry of oxo-functionalized graphene and this approach yields a high quality of graphene from flakes of water-soluble precursors. With this project, we want to advance the chemical methods for functionalization of graphene and aim on the synthesis of graphene derivatives with only one specific functional group to reduce the heterogeneity of this class of materials. This approach will lead to a deeper understanding of the properties. In particular, the C-C bond formation with oxo-functionalized graphene as precursor will give control over functionality and solubility of products for the first time and may be the basis to develop highly selective sensors in the future. Moreover mechanistic investigations for the formation of oxo-functionalized graphene will be conducted to identify the source of oxygen of its oxo-functionalities. That knowledge will be of utmost importance to either avoid or control the formation of lattice defects. We will synthesize functional charged pi-systems of different shape to study the interaction of the charged pi-systems with the surface of graphene and oxo-functionalized graphene, respectively. The evaluation of the photophysical and electronic properties will reveal how these systems can contribute to the development of selective sensors, solar cells or transparent and conductive coatings. The electrostatic and cation-pi interactions will be exploited to either stabilize graphene in solution or to tune the doping level of graphene. The evaluation of the molecular interaction with the surface of individual flakes of graphene and the change of electronic properties will be determined by Raman spectroscopy and in electronic devices. This approach allows quantifying the effect of doping. The gained knowledge will contribute to understand layered systems.Layered structures will be built by following self-assembly strategies. Layer-by-layer architectures of graphene derivatives and molecular layers will be prepared as novel graphite intercalation compounds with specific function for the first time. Stimuli, such as proton transfers will modulate the electronic properties of graphene inside the layered system. The changed electronic properties can subsequently related to pH values. These studies can lead to electronic pH sensors on the nm-scale. The basic investigations conducted in this project will advance the research field of organic electronics.

• DFG Programme: Research Grants