Current–voltage characteristics of single-molecule diarylethene junctions measured with adjustable gold electrodes in solution

Abstract

SummaryWe report on an experimental analysis of the charge transport through sulfur-free photochromic molecular junctions. The conductance of individual molecules contacted with gold electrodes and the current–voltage characteristics of these junctions are measured in a mechanically controlled break-junction system at room temperature and in liquid environment. We compare the transport properties of a series of molecules, labeled TSC, MN, and 4Py, with the same switching core but varying side-arms and end-groups designed for providing the mechanical and electrical contact to the gold electrodes. We perform a detailed analysis of the transport properties of TSC in its open and closed states. We find rather broad distributions of conductance values in both states. The analysis, based on the assumption that the current is carried by a single dominating molecular orbital, reveals distinct differences between both states. We discuss the appearance of diode-like behavior for the particular species 4Py that features end-groups, which preferentially couple to the metal electrode by physisorption. We show that the energetic position of the molecular orbital varies as a function of the transmission. Finally, we show for the species MN that the use of two cyano end-groups on each side considerably enhances the coupling strength compared to the typical behavior of a single cyano group.

Incorporating single molecules into electrical circuits. The role of the chemical anchoring group

“…55,90,92 A junction formation probability of 60% has been observed in the case of cyano-terminated diaryloligoynes, 90 which is similar to the percentages found for structurally similar OPE diamine junctions. 55,90,92 A junction formation probability of 60% has been observed in the case of cyano-terminated diaryloligoynes, 90 which is similar to the percentages found for structurally similar OPE diamine junctions.…”

Light‐Induced Switching of Tunable Single‐Molecule Junctions

“…The transmission for 1on t ( T ≈ 7 × 10 −4 ) is higher than for 2on t ( T ≈ 5 × 10 −5 to 2 × 10 − 4 ). Still, both values are higher than those observed for DAEs with shorter side‐arms and lower switching efficiency 15, 27. Apparently, decoupling of the excited states of the switching core by the OPE wires does not result in a reduced conductance.…”

Electronic transport through short dsDNA measured with mechanically controlled break junctions: New thiol–gold binding protocol improves conductance

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