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O: Fachverband Oberflächenphysik

O 55: Organic Molecules on Inorganic Substrates IV: Adsorption and Growth II

O 55.1: Talk

Wednesday, March 29, 2023, 15:00–15:15, CHE 91

Bias-dependent conductivity switching and rectification in metallocene-based molecular junctions — Yangbiao Liu¹, Andika Asyuda¹, Heinrich Lang², Egbert Zojer³, and •Michael Zharnikov¹ — ¹Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg, Germany — ²Fakultät für Naturwissenschaften, Anorganische Chemie, Technische Universität Chemnitz, D-09107 Chemnitz, Germany — ³Institute of Solid State Physics, NAWI Graz, Graz University of Technology, 8010 Graz, Austria

Self-assembled monolayers (SAMs) of ferrocenyl/ruthenocenyl-substituted biphenylthiolates and fluorenethiolates on Au(111) exhibit two distinct conductance states (CS) in two-terminal junctions featuring a sharp tip of eutectic GaIn as top electrode. When only negatively biasing the junction, the original, high CS is preserved, while the junction is switched to a low CS when applying only positive biases. Comparing the current values for these two states, one gets an effective rectification ratio of more than 1000 - a value comparable to the best performing molecular diodes but attained already at particularly low voltages. Significantly, the switching between the conduction states is reversible and the initial, high CS can be recovered by the application of a negative bias. Moreover, as shown by the example of one of the SAMs studied, when sweeping the junction alternatingly to the maximum positive and negative bias voltages (as usually done in literature), fully symmetric J-V curves are observed. This means that for a symmetric sweeping of the junction, the effective rectification disappears.