Evidence for Electron Transfer between Graphene and Non-Covalently Bound π-Systems

Area of Science:

• Materials Science
• Nanotechnology
• Organic Chemistry

Background:

• Hybridizing graphene with molecules offers potential for novel material applications.
• Characterizing these graphene-molecule hybrids requires advanced methods.

Purpose of the Study:

• To present a wet-chemical non-covalent functionalization method for graphene using cationic π-systems.
• To characterize the interaction between graphene and functionalizing molecules.
• To explore the doping effects and potential applications of the resulting hybrids.

Main Methods:

• Synthesis and characterization of tricationic benzimidazolium salts.
• Fabrication of graphene hybrids via non-covalent functionalization.
• Characterization using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS).
• Density Functional Theory (DFT) calculations.
• Fabrication and testing of graphene field-effect transistor (FET) devices.

Main Results:

• Successful non-covalent functionalization of graphene with tricationic benzimidazolium salts.
• Observation of p-doping in graphene due to the adsorbed cationic π-systems.
• Reduction of tricationic molecules via electron transfer from graphene, accompanied by counterion loss.
• Confirmation of strong p-doping in fabricated monolayer graphene/hybrid FET devices.

Conclusions:

• The developed method enables detailed characterization of graphene-molecule interactions.
• The observed p-doping effect in graphene is significant and controllable.
• These findings lay the groundwork for developing novel sensor applications based on analyte/molecule interactions and doping effects.