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Tuning ultrafast electron injection dynamics at organic-graphene/metal interfaces
Abhilash Ravikumar1, Gregor Kladnik, Moritz Müller
1Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 55, 20125 Milano, Italy. a.ravikumar@campus.unimib.it.
Nanoscale
|April 19, 2018
Summary
Ultrafast electron transfer from graphene to molecules is significantly slower on bilayer graphene due to substrate coupling differences. This impacts charge transfer dynamics at organic molecule-graphene interfaces.
Area of Science:
- Surface science
- Materials science
- Physical chemistry
Background:
- Graphene and bilayer graphene exhibit distinct electronic properties.
- Understanding charge transfer dynamics at interfaces is crucial for electronic applications.
- 4,4'-bipyridine serves as a model molecule for studying electron injection.
Purpose of the Study:
- To compare ultrafast charge transfer dynamics on epitaxial graphene versus bilayer graphene.
- To investigate the influence of graphene substrate coupling on electron injection.
- To elucidate the role of electronic states near the Fermi level.
Main Methods:
- First principles calculations.
- X-ray resonant photoemission spectroscopy.
- Utilizing 4,4'-bipyridine as a model system.
Main Results:
- Electron injection from substrate to molecule is approximately 4 times slower on bilayer graphene compared to epitaxial graphene.
- The observed difference is attributed to variations in the density of states near the Fermi level.
- Weakly coupled bilayer graphene exhibits slower charge transfer dynamics.
Conclusions:
- Graphene substrate coupling significantly influences ultrafast charge transfer dynamics.
- Differences in electronic structure dictate the efficiency of electron injection.
- This study provides insights into controlling charge transfer at organic-graphene interfaces.
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