Benchmarking break-junction techniques : electric and thermoelectric characterization of naphthalenophanes

Titelangaben

Hurtado-Gallego, Juan ; van der Poel, Sebastiaan ; Blaschke, Matthias ; Gallego, Almudena ; Hsu, Chunwei ; López-Nebreda, Rubén ; Mayor, Marcel ; Pauly, Fabian ; Agraït, Nicolás ; van der Zant, Herre S. J.:
Benchmarking break-junction techniques : electric and thermoelectric characterization of naphthalenophanes.
In: Nanoscale. Bd. 16 (2024) Heft 22 . - S. 10751-10759.
ISSN 2040-3372
DOI: https://doi.org/10.1039/d4nr00704b

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Abstract

Break-junction techniques provide the possibility to study electric and thermoelectric properties of single-molecule junctions in great detail. These techniques rely on the same principle of controllably breaking metallic contacts in order to create single-molecule junctions, whilst keeping track of the junc- tion’s conductance. Here, we compare results from mechanically controllable break junction (MCBJ) and scanning tunneling microscope (STM) methods, while characterizing conductance properties of the same novel mechanosensitive para- and meta-connected naphtalenophane compounds. In addition, thermo- power measurements are carried out for both compounds using the STM break junction (STM-BJ) tech- nique. For the conductance experiments, the same data processing using a clustering analysis is per- formed. We obtain to a large extent similar results for both methods, although values of conductance and stretching lengths for the STM-BJ technique are slightly larger in comparison with the MCBJ. STM-BJ thermopower experiments show similar Seebeck coefficients for both compounds. An increase in the Seebeck coefficient is revealed, whilst the conductance decreases, after which it saturates at around 10 μV K−1. This phenomenon is studied theoretically using a tight binding model. It shows that changes of molecule-electrode electronic couplings combined with shifts of the resonance energies explain the correlated behavior of conductance and Seebeck coefficient.