- Titel
- Categorising current-voltage curves in single-molecule junctions and their comparison to Single-Level Model
- Zitierfähige Url:
- https://nbn-resolving.org/urn:nbn:de:bsz:14-qucosa2-933444
- Erstveröffentlichung
- 2024
- Datum der Einreichung
- 07.06.2024
- Datum der Verteidigung
- 09.08.2024
- Abstract (EN)
- This thesis investigates the mechanically controlled break junctions, with a particular emphasis on elucidating the behaviour of molecular currents at room temperature. The core of this experimental investigation involves a detailed analysis of conductance, examining how it varies over time and with changes in the gap between electrodes. Additionally, this study thoroughly evaluates transmission properties, coupling effects, and current characteristics. A pivotal aspect of the research was the meticulous current measurement, followed by carefully selecting optimal data sets. This process set the stage for an in-depth analysis of resonant tunnelling phenomena observed through a single channel. Notably, these experiments were conducted under open atmospheric conditions at room temperature. A significant finding from this study is the recognition that our current model requires refinement. This adjustment is necessary to more accurately encapsulate a broader spectrum of molecular transport mechanisms. Furthermore, this work significantly advances our comprehension of quantum effects in single-molecule junctions, particularly concerning similar molecules to Corannulene extending to some organometallics. One of the essential disclosures is the identification of deviations in the transport model, primarily attributable to electron-electron interactions. This insight is crucial as it paves the way for developing a more comprehensive and precise model, enhancing our understanding of molecular-scale electronic transport.
- Freie Schlagwörter (EN)
- SLM, molecular electronics, organic electronics, single level model
- Klassifikation (DDC)
- 530
- Klassifikation (RVK)
- UO 3000
- GutachterIn
- Prof. Dr. Artur Erbe
- BetreuerIn Hochschule / Universität
- Dr. Francesca Moresco
- BetreuerIn - externe Einrichtung
- Prof. Dr. Artur Erbe
- Den akademischen Grad verleihende / prüfende Institution
- Technische Universität Dresden, Dresden
- Sonstige beteiligte Institution
- Helmholtz-Zentrum Dresden-Rossendorf, Dresden-Rossendorf
- Version / Begutachtungsstatus
- publizierte Version / Verlagsversion
- URN Qucosa
- urn:nbn:de:bsz:14-qucosa2-933444
- Veröffentlichungsdatum Qucosa
- 20.08.2024
- Dokumenttyp
- Masterarbeit / Staatsexamensarbeit
- Sprache des Dokumentes
- Englisch
- Lizenz / Rechtehinweis
CC BY-NC-ND 4.0- Inhaltsverzeichnis
List of Figures xi List of Tables xiii Acronyms xiii Terminology xv Symbols xvi Abstract xvii 1 Introduction 1 1.1 Motivation and Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Molecular Electronics Background . . . . . . . . . . . . . . . . . . . . . . . . 2 1.3 RelatedWork, the State of Art . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.4 Structure of the work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 Methods and Implementations 7 2.1 Mechanically Controlled Break Junctions Principle . . . . . . . . . . . . . . 8 2.1.1 Setups forMCBJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.2 Measurement Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.1.3 Electrical Diagramof theMeasurement . . . . . . . . . . . . . . . . . 15 2.1.4 Criteria to Select the Data . . . . . . . . . . . . . . . . . . . . . . . . 15 2.2 Experiment Realisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3 Molecules and Transport 20 3.1 Molecules in the Scope of this Thesis . . . . . . . . . . . . . . . . . . . . . . 20 3.1.1 Fixation of pi-Conjugated Molecules on Gold Surfaces via Thiol Bond 20 i 3.2 Ballistic Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3.2.1 Tunnelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3.3 Single Level Model (SLM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.3.1 Chemical Nature of theMolecular Channels . . . . . . . . . . . . . . 24 3.4 TransportMechanisms inMolecules attached toMCBJ . . . . . . . . . . . . 25 4 Results and Discussions 28 4.1 Discussions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 4.1.1 Opening Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 4.1.2 HistogramfromtheMeasurements . . . . . . . . . . . . . . . . . . . 30 4.2 Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 4.2.1 Current in Toluene . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 4.2.2 Current in Corannulene . . . . . . . . . . . . . . . . . . . . . . . . . 44 4.2.3 Current in Fe+3 Salen . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.2.4 Current Measurement after Consecutive Opening - Case Study: Fe+3 Salen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 4.2.5 Single LevelModel - Case Study: Corannulene . . . . . . . . . . . . . 53 4.2.6 Lorentzian Distribution and Fitting in Salen organometallics and Corannulene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.2.7 Single Level Model - Study of the case: Fe+3 Salen . . . . . . . . . . 66 4.3 Transmission and Coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 4.3.1 Transmission and Coupling - Case Study: Fe+3 Salen . . . . . . . . . 70 4.4 Conclusive Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 4.4.1 Hypothesis of Scattering . . . . . . . . . . . . . . . . . . . . . . . . . 76 5 Conclusion and Further Work 78 5.1 The CurrentMeasurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 5.2 Further Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 A Current with Mean Normalization i A.1 Categories ofMeasurements . . . . . . . . . . . . . . . . . . . . . . . . . . . ii A.1.1 Measurements without hysteresis or very small . . . . . . . . . . . . . ii A.1.2 Measurements with hysteresis . . . . . . . . . . . . . . . . . . . . . . vi A.2 Measurements without Fitting . . . . . . . . . . . . . . . . . . . . . . . . . . xii B Our best fits where the SLM fails xi