Influence of the Number of Anchoring Groups on the Electronic and Mechanical Properties of Benzene‐, Anthracene‐ and Pentacene‐Based Molecular Devices

Abstract

One of the central issues of molecular electronics (ME) is the study of the molecule-metal electrode contacts, and their implications for the conductivity, charge-transport mechanism, and mechanical stability. In fact, stochastic on/off switching (blinking) reported in STM experiments is a major problem of single-molecule devices, and challenges the stability and reliability of these systems. Surprisingly, the ambiguous STM results all originate from devices that bind to the metallic electrode through a one-atom connection. In the present work, DFT is employed to study and compare the properties of a set of simple acenes that bind to metallic electrodes with an increasing number of connections, in order to determine whether the increasing numbers of anchoring groups have a direct repercussion on the stability of these systems. The conductivities of the three polycyclic aromatic hydrocarbons are calculated, as well as their transmission spectra and current profiles. The thermal and mechanical stability of these systems is studied by pulling and pushing the metal-molecule connection. The results show that molecules with more than one connection per electrode exhibit greater electrical efficiency and current stability.

Coherent Electron Transmission across Nanographenes Tethered to Gold Electrodes: Influence of Linker Topology, Ribbon Width, and Length

“…Previous studies on highly symmetric GNR molecules show that, when multiple linking groups are present, a strong interfacial coupling gives rise to an enhanced conductance of highly symmetric molecular junctions. 61,62 In our case, the molecules are not symmetric so that the benefits of multiple linkers are not limited to the symmetry effects depicted in refs 60 and 61. In particular, the alignment of the HOMO with respect to the Fermi energy of gold is also responsible for the increase in conductance, since the two anchoring groups induce a larger broadening of the transmission peak due to the coupling between gold and the molecule and hence a higher transmission value at zero volt.…”

Synthesis of Electro-active Compounds Suitable for Adsorption on Metal Surfaces

“…As mentioned in section I, multidentate thiols have often been used and the influence of the number of anchoring sulfur groups on the properties has been examined theoretically for benzene-and anthracene-based molecular devices. 25 Generation of TTF-tetrathiolate by treatment of the tetrakis(cyanoethyl) compound 29 with caesium hydroxide using Becher's method, 19 has been used to form monolayers with structure 30 on gold (Scheme 8). 26 Application of the same procedure to the TTF derivatives 31 with long alkyl chains at the other side likewise gives self-assembled monolayers based on structure 32.…”

A Bipodal Dicyano Anchor Unit for Single‐Molecule Spintronic Devices

“…Recently, a variety of S-based multidentate anchor groups have been widely investigated in an attempt to enhance the stability and versatility of self-assembled monolayers (SAMs). [36][37][38][39][40][41][42][43] [30] We employed 7,7,8,8-tetracyanoquinodimethane (TCNQ) as a model system, the structure of which is shown in Figure 2.…”

“…[36,37] This is a standard method to design molecular electronic devices and obtain a detailed understanding of coherent electron transport through a single molecule. [36][37][38][39][40][41][42][43]…”