Probing the relationship of cations-graphene interaction strength with self-organization behaviors of the anions at the interface between graphene and ionic liquids

The influence of molecular cations on the dynamic self-organization of anion at the interface between graphene and ionic liquid (IL) is investigated by selecting same anion ILs (N,N-diethyl-N-(2-methoxyethyl)-N-methylammonium bis(trifluoromethylsulfonyl)imide (DEME-TFSI) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-TFSI)) as the top gate of double-gate graphene filed effect transistors (DG-GFETs). The selected ILs have similar viscosity and conductivity but exhibit distinctly different effects on device performance. From electric transport properties of the DG-GFETs and infrared spectroscopy, it is found that stronger BMP-graphene interactions facilitate faster self-organization of the TFSI anions on graphene. The results introduce an important role of the interfacial cation-graphene interactions that contribute to molecular self-organization, and clearly show the significant impact interfacial effects offer for tuning macroscopic device performance.