Benedikt Klein and coworkers of SFB 1083, together with external collaborators, have gained new insight into interfacial interactions of Stone-Wales graphene defects by using molecular models.
Graphene is an astonishing two-dimensional material with diverse and technologically important properties. However, these properties are heavily dependent on topological defects, which have a direct impact on the graphene/metal interface. A common defect is the Stone-Wales (SW) defect, consisting of two five- and two seven-membered rings resulting in a non-alternating bonding situation. Researchers of the SFB 1083 projects A4 (Gottfried) and A6 (Tonner) investigated the interface between a SW defect and a metal by mimicking the defect with the molecule azupyrene. Pyrene was used as a model for defect-free graphene of the same size as azupyrene. The experiments were complemented by extensive modelling of the graphene-embedded defects.
In the present work, it was shown by a multi-technique approach (XPS/UPS, NIXSW, NEXAFS, TPD, LT-AFM, DFT) that the embedded defects, modelled by azupyrene, undergo enhanced bonding and electron transfer with a Cu(111) surface. This indicated by increased bond energies of 68 kJ/mol, by 0.9 Å reduced bond distances and enhanced charge transfer. The consistent experimental results were corroborated by DFT calculations.
The defect-induced enhanced electronic coupling at the graphene/metal interface is expected to have significant impact on the performance of (opto-)electronics, e.g., by increasing charge injection rates. Tailoring the topological structure of graphene layer may result in the development of new or imprived devices.
B.P. Klein, A. Ihle, S.R. Kachel, L. Ruppenthal, S.J. Hall, L. Sattler, S.M. Weber, J. Herritsch, A. Jaegermann, D. Ebeling, R.J. Maurer, G. Hilt, R. Tonner-Zech, A. Schirmeisen, J.M. Gottfried
Topological Stone–Wales Defects Enhance Bonding and Electronic Coupling at the Graphene/Metal Interface
ACS Nano (2022) DOI:10.1021/acsnano.2c01952
Prof. Dr. J. Michael Gottfried
SFB 1083 project A4
Tel.: 06421 28-22541