Abstract
Diarylethene-derived molecules alter their electronic structure upon transformation between the open and closed forms of the diarylethene core, when exposed to ultraviolet (UV) or visible light. This transformation results in a significant variation of electrical conductance and vibrational properties of corresponding molecular junctions. We report here a combined experimental and theoretical analysis of charge transport through diarylethene-derived single-molecule devices, which are created using the mechanically controlled break-junction technique. Inelastic electron tunneling (IET) spectroscopy measurements performed at 4.2 K are compared with first-principles calculations in the two distinct forms of diarylethenes connected to gold electrodes. The combined approach clearly demonstrates that the IET spectra of single-molecule junctions show specific vibrational features that can be used to identify different isomeric molecular states by transport experiments.
Highlights
Molecular junctions hold promise for the realization of novel miniaturized electronic circuits [1,2,3,4,5,6] as well as for thermoelectric energy conversion devices [7,8,9,10]
The absorption band of the closed form extends to a higher wavelength than those of the open form, suggesting that the closed form has a smaller highest occupied molecular orbital (HOMO)–LUMO gap
We have found that the HOMO is much closer to the Fermi energy than the LUMO, but the energy-dependent transmission still suggests that the single-level toy model is not straightforwardly applicable
Summary
Molecular junctions hold promise for the realization of novel miniaturized electronic circuits [1,2,3,4,5,6] as well as for thermoelectric energy conversion devices [7,8,9,10]. Measured electrical conductance and IET spectra are compared with first-principles calculations in open and closed forms of the photochromic molecule.
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