Functionality of ruthenium complex self-assembled multilayer-based junctions at a low (~5%) and high (~50%) relative humidity

In the search of small and functional molecular devices, we have created and investigated 20 different self-assembled multilayers (SAMTs) each consisting of two self-assembled monolayers (SAM) on top of each other. We compare the molecular combinations to their inverse combinations, investigate their length dependence on the conductance and look for interesting features. Each SAM consists of one type of molecule (there are five different ruthenium complex molecules in total) and each bilayer is grown on an indium tin oxide substrate. Then current-voltage (I-V) curves are taken using conductive atomic force microscopy (C-AFM) to characterize the samples after the relative humidity (RH) of the setup has been brought to ≈ 5% and ≈ 50% respectively and the rectification ratio (RR) for each molecular combination is calculated. Double layers consisting of the same Ru-complexes and combinations of different molecules are measured. We find that while the shape of the I-V curves and the...Show moreIn the search of small and functional molecular devices, we have created and investigated 20 different self-assembled multilayers (SAMTs) each consisting of two self-assembled monolayers (SAM) on top of each other. We compare the molecular combinations to their inverse combinations, investigate their length dependence on the conductance and look for interesting features. Each SAM consists of one type of molecule (there are five different ruthenium complex molecules in total) and each bilayer is grown on an indium tin oxide substrate. Then current-voltage (I-V) curves are taken using conductive atomic force microscopy (C-AFM) to characterize the samples after the relative humidity (RH) of the setup has been brought to ≈ 5% and ≈ 50% respectively and the rectification ratio (RR) for each molecular combination is calculated. Double layers consisting of the same Ru-complexes and combinations of different molecules are measured. We find that while the shape of the I-V curves and the conductance of the combinations are different compared to those of their inverse combination, the rectification ratio (RR) (and in particular the direction of rectification) is not. The highest RR found is RRhumid = 10^(-2.0±0.6) at 1.0 V for the combination with bottom layer 1-Ru-N and top layer 2-Ru-N (decoupled). Furthermore, we see that while most bilayers have current values that agree to a conductance that decreases exponentially with the length, some do not. Lastly, we observe hysteresis in three samples. Our findings in this exploratory experiment contribute to the knowledge of charge transport in junctions consisting of layers of complex molecules.Show less

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Functionality of ruthenium complex self-assembled multilayer-based junctions at a low (~5%) and high (~50%) relative humidity