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O: Fachverband Oberflächenphysik

O 49: Poster Session - Organic Molecules on Inorganic Substrates: Electronic, Optical and Other

O 49.8: Poster

Tuesday, March 17, 2020, 18:15–20:00, P2/EG

First Principles Studies of Electrical Conductance and Thermopower Properties of π-Conjugated Organometallic Complexes in Single Molecule Junctions — •Jannis Jung¹, Tatsuhiko Ohto², Hirokazu Tada², and Doreen Mollenhauer¹ — ¹Institute of Physical Chemistry, Justus Liebig University, Giessen, Germany — ²Division of Frontier Material Science, Osaka University, Osaka, Japan

Single molecule junctions, consisting of a molecule connecting two bulk material electrodes, have a long history of research, which focuses on their electrical properties and uses in electronics. In particular, molecular junctions containing organometallic complexes showed high Seebeck coefficients and low thermal conductance, making them a promising thermoelectric material.

Here, the influence of the binding nature between a complex and differently structured gold surfaces as well as the influence of large side chains of the ligands to the electron transmission was investigated by density functional theory calculations using the Non-Equilibrium Green’s Function (NEGF) method. Therefore, we studied junctions containing transition metal (Ru and Pt) complexes with highly π-conjugated ligands binding to different surface contacts. We showed a shift of the conductive (HOMO) orbitals towards the Fermi energy, effectively increasing the Seebeck Coefficient. Furthermore, intramolecular dispersion interactions can lead to a decrease of the electric conductance.