Molecular scale electronics | EPFL Graph Search

Molecular scale electronics, also called single-molecule electronics, is a branch of nanotechnology that uses single molecules, or nanoscale collections of single molecules, as electronic components. Because single molecules constitute the smallest stable structures imaginable, this miniaturization is the ultimate goal for shrinking electrical circuits. The field is often termed simply as "molecular electronics", but this term is also used to refer to the distantly related field of conductive polymers and organic electronics, which uses the properties of molecules to affect the bulk properties of a material. A nomenclature distinction has been suggested so that molecular materials for electronics refers to this latter field of bulk applications, while molecular scale electronics refers to the nanoscale single-molecule applications treated here. Fundamental concepts Conventional electronics have traditionally been made from bulk materials. Ever since their invention in 19

Templating Approach Towards Lamellar Carbon Nanomaterials from Oligo(phenylene) Amphiphiles

Dragana Paripovic

Templating approaches based on the self-assembly of block-copolymers represent a powerful tool for the preparation of ordered carbon-containing nanomaterials. Combining such strategies with the use of well-defined amphiphilic precursors with sp2-carbon-rich cores provides a way to better tailor carbon nanostructures with predetermined morphologies. This thesis, therefore, explores a soft templating approach using the self-assembly of linear poly(ethylene oxide)-substituted oligo(phenylene) amphiphiles as both a template for the formation of lamellar structures and sp2-carbon-rich source for the synthesis of ordered carbon nanostructures. Our investigations showed that a series of such coil-rod-coil molecules with different numbers of phenylene units in their core exhibited a rich polymorphism of tilted lamellar phases in bulk over a wide range of temperatures. We found that the self-assembly of the oligo(phenylene) rods into lamellar domains induced nanoscopic confinement of the poly(ethylene oxide) chains, resulting in a significant increase of their melting point to temperatures of up to 228 °C. Moreover, the cooperative self-assembly of the hexa(phenylene) amphiphile with sol-gel aluminosilicate precursors enhanced by solvent evaporation, and the subsequent carbonization of the obtained mesophases at 600 °C successfully furnished lamellar carbon-aluminosilicate nanocomposites. Following this approach, macroscopically oriented films of nanocomposites were prepared on a substrate by a shearing technique. Detailed structural characterization of the film morphology revealed lamellae with macroscopic order, an ¿edge-on¿ orientation relative to the substrate, as well as periodicities on the order of the molecular length scale. Furthermore, an ordered lamellar porous carbon was prepared by successfully etching the aluminosilicate phase, giving rise to a porous material with a large surface area that was appeared to be promising for hydrogen storage applications.

EPFL2014

Controlling Single Molecule Conductance by a Locally Induced Chemical Reaction on Individual Thiophene Units

Klaus Kern, Hagen Klauk, Ivan Pentegov, Verena Katharina Schendel, Uta Schlickum, Peter Wahl

Among the prerequisites for the progress of single-molecule-based electronic devices are a better understanding of the electronic properties at the individual molecular level and the development of methods to tune the charge transport through molecular junctions. Scanning tunneling microscopy (STM) is an ideal tool not only for the characterization, but also for the manipulation of single atoms and molecules on surfaces. The conductance through a single molecule can be measured by contacting the molecule with atomic precision and forming a molecular bridge between the metallic STM tip electrode and the metallic surface electrode. The parameters affecting the conductance are mainly related to their electronic structure and to the coupling to the metallic electrodes. Here, the experimental and theoretical analyses are focused on single tetracenothiophene molecules and demonstrate that an in situ-induced direct desulfurization reaction of the thiophene moiety strongly improves the molecular anchoring by forming covalent bonds between molecular carbon and copper surface atoms. This bond formation leads to an increase of the conductance by about 50 % compared to the initial state.

WILEY-V C H VERLAG GMBH2020

Lamellar carbon-aluminosilicate nanocomposites with macroscopic orientation

Enzo Bomal, Yannik Fontana, Anna Fontcuberta i Morral, Holger Frauenrath, Emadeddin Oveisi, Dragana Paripovic

Novel preparative approaches towards lamellar nanocomposites of carbon and inorganic materials are relevant for a broad range of technological applications. Here, we describe how to utilize the co-assembly of a liquid-crystalline hexaphenylene amphiphile and an aluminosilicate precursor to prepare carbon-aluminosilicate nanocomposites with controlled lamellar orientation and macroscopic order. To this end, the shear-induced alignment of a precursor phase of the two components resulted in thin films comprising lamellae with periodicities on the order of the molecular length scale, an "edge-on" orientation relative to the substrate and parallel to the shearing direction with order on the centimeter length scale. The lamellar structure, orientation, and macroscopic alignment were preserved in the subsequent pyrolysis that yielded the corresponding carbon-aluminosilicate nanocomposites.

ROYAL SOC CHEMISTRY2021

Templating Approach Towards Lamellar Carbon Nanomaterials from Oligo(phenylene) Amphiphiles

Dragana Paripovic

EPFL2014