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Evidence for Electron Transfer between Graphene and Non‐Covalently Bound π‐Systems
Author(s) -
Brülls Steffen M.,
Cantatore Valentina,
Wang Zhenping,
Tam Pui Lam,
Malmberg Per,
Stubbe Jessica,
Sarkar Biprajit,
Panas Itai,
Mårtensson Jerker,
Eigler Siegfried
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202000488
Subject(s) - graphene , materials science , molecule , raman spectroscopy , doping , chemical physics , covalent bond , x ray photoelectron spectroscopy , nanotechnology , steric effects , monolayer , electron transfer , counterion , chemical engineering , photochemistry , chemistry , ion , organic chemistry , optoelectronics , physics , engineering , optics
Hybridizing graphene and molecules possess a high potential for developing materials for new applications. However, new methods to characterize such hybrids must be developed. Herein, the wet‐chemical non‐covalent functionalization of graphene with cationic π‐systems is presented and the interaction between graphene and the molecules is characterized in detail. A series of tricationic benzimidazolium salts with various steric demand and counterions was synthesized, characterized and used for the fabrication of graphene hybrids. Subsequently, the doping effects were studied. The molecules are adsorbed onto graphene and studied by Raman spectroscopy, XPS as well as ToF‐SIMS. The charged π‐systems show a p‐doping effect on the underlying graphene. Consequently, the tricationic molecules are reduced through a partial electron transfer process from graphene, a process which is accompanied by the loss of counterions. DFT calculations support this hypothesis and the strong p‐doping could be confirmed in fabricated monolayer graphene/hybrid FET devices. The results are the basis to develop sensor applications, which are based on analyte/molecule interactions and effects on doping.