Photo-modulable molecular transport junctions based on organometallic molecular wires

Abstract

Photo-modulable molecular transport junctions are developed via on-wire lithography-fabricated nanogap functionalized with a dithienylethene unit bearing two ruthenium fragments. A reversible and repeatable bi-state conductive switching upon alternate irradiation of UV and visible light can be distinctly observed. Theoretical calculations further suggest that bi-directional isomerization is due to the ruthenium moieties that modulate judiciously the electronic coupling between the photochromic part and the metal electrodes, and that the differences in electronic structure between the two isomers (open and closed states) are responsible for conductivity switching.

Orthogonally modulated molecular transport junctions for resettable electronic logic gates

“…Besides the conductivity disparity, the current ratios between ‘1’ and ‘0’ states of different devices exhibit a slight fluctuation (Supplementary Tables 1 and 2). However, these ratios are all located in the range of 10–20 times, which are consistent with theoretical44 or experimental1334 closed/open current ratios of single DTE derivatives, taking into account the high number of molecules loaded in the nanogaps. Such random fluctuation may be ascribed to slightly different orientations and conformations of functional molecules within each working device with variable roughness affecting the efficiency of the switching events.…”

“…1a) can achieve photo-triggered isomerization both in solution and in solid-state nanodevices. As previously demonstrated44, reversible photochromic processes are achieved upon irradiation with UV light for ring closure and visible light for ring opening in solution (Fig. 1b).…”

“…Therefore complex 1 is an ideal candidate to explore photo-/electro-switchable MTJs when incorporated into a pair of nanoelectrodes, as illustrated in Fig. 1d, which is also strongly supported by the theoretical calculations of molecular geometric reorganization and transmittance process through the molecule44.…”

Lanthanide Sensitization with Ruthenium Carbon-Rich Complexes and Redox Commutation of Near-IR Luminescence

“…In a similar way, the 1 H NMR signals from the dppe ligand are very deshielded with, for example, the o-phenyl proton signals at 13.44 and 11.59 ppm (7.17 and 6.97 ppm in [4]OTf) or the CH 2 −P signals at 7.86 and 6.68 ppm (3.30 and 3.20 ppm in [4]OTf). Finally, line broadening and paramagnetic shifts of the azafluorene moiety are also more important for [4]OTf. These differences may result from a different orientation of the anisotropy tensor of the Yb ion in comparison to that of the Ru(dppe) fragment in the allenylidene and acetylide complexes, since the Ru−Ln distance should be rather similar in both types of complexes.…”

Metal complexes in molecular junctions

“…25 In that direction, we recently developed a photo-modulatable molecular transport junction via onwire lithography-fabricated nanogaps functionalized with a dithienylethene (DTE) unit bearing two ruthenium fragments (Scheme 5). 26 Although the switching rates need to be improved for practical applications, a reversible and repeatable bi-state conductive switching upon alternate irradiation of UV and visible light could be distinctly observed. Theoretical calculations further suggest: (i) that the ruthenium acetylide moieties adjust judiciously the electronic coupling of the DTE fragment with the metal electrodes, avoiding electrode quenching of excited states upon irradiation as usually observed with metallic electrodes, and (ii) that the delocalization of the HOMO of the closed isomer lying near the Fermi level of the junction is high enough to lead to an efficient conductivity.…”