Bottom‐Up Molecular Tunneling Junctions Formed by Self‐Assembly

Abstract

This Minireview focuses on bottom‐up molecular tunneling junctions – a fundamental component of molecular electronics – that are formed by self‐assembly. These junctions are part of devices that, in part, fabricate themselves, and therefore, are particularly dependent on the chemistry of the molecules selected. The discussion covers the history of these junctions as well as recent advances. It is broken into the broad categories of conformal and rigid contacts, which place different constraints on the molecules used to form the junctions. The intention of this Minireview is to give an overview of research efforts in molecular electronics that is targeted at chemists, whose efforts are playing an increasingly important role in molecular electronics.

Conformation-driven quantum interference effects mediated by through-space conjugation in self-assembled monolayers

“…Measuring well characterized, high-quality SAMs is paramount as, unlike top-down, single-molecule techniques (break junctions and so on) or few molecules techniques (conducting-probe AFM and so on. ), EGaIn is a bottom-up, large-area technique7 and is therefore sensitive to the detailed structure of the SAM because it defines the physical shape of the junction and the EGaIn//SAM interface212223.…”

“…And moving from top-down spectroscopic tools towards functional, device-like platforms2344041424344 will probably involve bottom-up molecular tunnelling junctions based on SAMs7, in which molecules are in a (liquid) crystalline state. Such junctions represent a form of nanotechnology closest to Nature in that the nanoscopic structure and function are simultaneously and inseparably defined by the equilibrium self-assembly of molecules; differences of 0.06 Å–0.11 Å can completely suppress QI in DFT simulations.…”

“…In self-assembled monolayers (SAMs), molecules are fixed in a specific conformation and binding geometry, arranging themselves in ordered, two-dimensional crystal-like domains. Tunnelling junctions comprising SAMs, therefore, fix molecules in a specific conformation and binding geometry that defines the smallest dimension of the junction, through which charges tunnel; they are a form of bottom-up nanotechnology67. The effects of conformational confinement on molecular charge-transport are particularly interesting in the case of π -conjugated molecules because conductivity (hopping) and transmission (tunnelling) are strongly related to the extent of electronic delocalization.…”

Advantages of Prefabricated Tunnel Junction-Based Molecular Spintronics Devices

“…12 However, developing a reproducible, commercially viable, long lasting and economical molecular device fabrication technology continues to be a major impediment. [11][12][13] Most of the molecular device fabrication approaches 5,12,14 attempted so far can be categorized under the following four groups 3,4 (i) Molecules sandwiched between a conducting¯lm and scanning tunneling microscope (STM) or conducting probe atomic force microscope (CPAFM) tip [ Fig. 1(a)], 15 (ii) molecular monolayer sandwiched between two conducting electrodes [ Fig.…”

Production of Liquid Metal Spheres by Molding

“…The droplets are composed of eutectic gallium and indium (EGaIn, 75 wt% gallium and 25 wt% OPEN ACCESS indium), which is liquid at room temperature [1] with low viscosity and high electrical conductivity (2.94 × 10 −5 ohm cm) [2]. EGaIn has been utilized in various applications, such as deformable antennas [3][4][5][6], self-healing wires [7,8], ultra-stretchable fibers [9], multiaxial stretchable interconnects [10,11], soft electrodes [12], microfluidic electronics [13,14] and sensors [15,16]. These applications are enabled by a thin oxide skin that forms spontaneously on the metal at ambient conditions, which allows EGaIn to form stable shapes that would otherwise be prohibited by surface tension [17,18].…”