Selective Fabrication of Single‐Molecule Junctions by Interface Engineering

Abstract

Recent progress in addressing electrically driven single‐molecule behaviors has opened up a path toward the controllable fabrication of molecular devices. Herein, the selective fabrication of single‐molecule junctions is achieved by employing the external electric field. For molecular junctions with methylthio (–SMe), thioacetate (–SAc), amine (–NH2), and pyridyl (–PY), the evolution of their formation probabilities along with the electric field is extracted from the plateau analysis of individual single‐molecule break junction traces. With the increase of the electric field, the SMe‐anchored molecules show a different trend in the formation probability compared to the other molecular junctions, which is consistent with the density functional theory calculations. Furthermore, switching from an SMe‐anchored junction to an SAc‐anchored junction is realized by altering the electric field in a mixed solution. The results in this work provide a new approach to the controllable fabrication and modulation of single‐molecule junctions and other bottom‐up nanodevices at molecular scales.

A review of oligo(arylene ethynylene) derivatives in molecular junctions

“…261 Another innovative development is the use of an external electric field to influence junction formation probability in STM-BJ experiments. 262 It was found that OPEs with methylthio anchoring groups were increasingly likely to form junctions as the bias was increased, whereas thiol, amine and pyridyl anchors all showed reduced junction formation probability with increasing bias. This meant it was possible to demonstrate selective, preferential junction formation in a mixture of methylthioand thiol-anchored OPEs based on the applied electric field.…”

“…This meant it was possible to demonstrate selective, preferential junction formation in a mixture of methylthioand thiol-anchored OPEs based on the applied electric field. 262 OAE derivatives are outstanding candidate molecules for developing novel molecular junction methodologies and as benchmark compounds for investigations of modifications to existing techniques. The ease with which structural modification can be achieved facilitates the translation of OAE wires to new electrode surfaces that require alternative anchoring groups.…”

Tracking Confined Reaction Based on Host–Guest Interaction Using Single‐Molecule Conductance Measurement

“…First, the strong electric field in the nanogap has an enrichment influence on molecular adsorption, so as to improve the local concentration and accelerate the reaction. [17] Second, the strong electric field, as generated by the applied bias, can further accelerate the reaction rate. [27] This finding also demonstrated the advantage of STM-BJ method, since it provides a safe and convenient method to study reaction under strong electric fields.…”

Grid-Based Correlation Analysis to Identify Rare Quantum Transport Behaviors

“…Single-molecule electronics have the potential to enable cheap and efficient circuit fabrication at the ultimate size limit and also provide an appealing test-bed for exploring intriguing physical phenomena at the nanoscale such as quantum interference, − spin filtering, , and interfacial coupling. − A significant and ongoing challenge in the investigation of transport through single-molecule systems, however, is extracting meaning from the large and stochastic data sets typically produced by experimental techniques such as the scanning tunneling microscope break junction (STM-BJ) − and mechanically controlled break junction (MCBJ). − Both of these methods involve forming and then breaking a thin metal constriction to create a single-molecule junction in the nanogap between two metal electrodes. The primary data collected is the conductance ( G = I / V ) through the junction during the breaking process as a function of how much the two sides have been pulled apart, known as a “breaking trace”.…”

“…The magnitude of this so-called “molecular yield” varies depending on the binding group strength, − molecular concentration, and other unknown or uncontrolled variables. , Figure uses simulated traces to illustrate that, for short molecules whose molecular plateaus mostly overlap with the tunneling background, low molecular yield can make the molecular signature functionally impossible to identify in both the 1D and 2D histograms. Partially for this reason, most break junction experiments focus on systems with molecular yields >10%, ,,,,, and often approaching 100%, ,, because this produces histograms with clear molecular features. However, high molecular yields increase the risk of measuring multi-molecule rather than the desired single-molecule features .…”