Dynamic percolation theory is a relatively simple mathematical model of a disordered system that relates concentration of conductor sites within a theoretical lattice structure to the flow or percolation of charge, particularly ionic diffusion. Below a threshold concentration, or the percolation threshold, the substance is an insulator, and above that concentration it is a conductor. Over the past 10 years, Ratner and Nitzan have examined the properties both of electron transfer within molecules and electron transport in molecular wire junctions 11
Nov 29, Adding an optoelectronic component to molecular electronics Nanowerk Spotlight One of the many fascinating concepts in nanotechnology is the vision of molecular electronics where researchers are investigating nanostructured materials to build electronics from individual molecules.
If realized, the shift in size from even the most densely packed computer chip today would be staggering.
To get a feel for the dimensions involved, just consider that a single drop of water contains more molecules approx. The nanoelectronics engineers of the future might be capable of using individual molecules to perform the functions in an electronic circuit that are performed by semiconductor devices today.
Molecular electronics aims at the fundamental understanding of charge transport through molecules and is motivated by the vision of molecular circuits to enable miniscule, powerful and energy efficient computers. A research team in Germany has now demonstrated that rigidly wired molecules can emit light under voltage bias.
This result is important for fundamental science but it also adds to the molecular electronics vision an optoelectronic component, i.
For this purpose, a team led by Krupke and Marcel Mayora professor of chemistry at the University of Basel in Switzerland, synthesized a specifically designed rod-like molecule with a fluorescent core and electrodes of carbon nanotubes.
The researchers developed a special technique that allowed them to place this molecule between electrically biased carbon nanotube electrodes. They then used the spectroscopic fingerprint of the molecule as evidence for the molecular electroluminescence. Moreover the electronic and optical properties of the molecule and the carbon nanotube electrodes had to be tailored such that electron transport and light emission is possible.
After dielectrophoretic deposition ba metallic nanotube black bridges palladium electrodes grey and is free-standing above a trench in silicon oxide green. Electrical breakdown opens a gap in the nanotube c. Light emission from the molecule under voltage bias V is detected and analyzed in an optical microscope setup e, not shown.
Another team member, Christoph W. He was then able to place the molecules from solution in between the nanotube electrodes by dielectrophoresis, an electric field-induced form of self-organization. Krupke notes that the necessary stability of the nanotube-molecule-nanotube junctions to survive high biasing is provided by special anchor groups at the molecule ends.
The team is currently fabricating junctions with various central chromophores to obtain molecular light-emitting devices that operate at different emission wavelengths. A major challenge will be to tailor molecules with a level energy scheme to reduce non-radiative electron transfer.
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The quest for a molecular rectifier is among the major challenges of molecular electronics. We introduce three simple rules to design an efficient rectifying molecule and demonstrate its functioning at the theoretical level, relying on the NEGF-DFT technique.
With “smaller and faster” as the driving mantra of the electronics industry, single-molecule devices represent the ultimate limit in electronic miniaturization. In , molecular electronics pioneers Mark Ratner and Arieh Aviram theorized that an asymmetric molecule could act as a rectifier, a one-way conductor of electric current. In nanotechnology: Molecular electronics. The use of molecules for electronic devices was suggested by Mark Ratner of Northwestern University and Avi Aviram of IBM as early as the s, but proper nanotechnology tools did not become available until the turn of the 21st century. Avik Ghosh Research Professor, Theoretical Condensed Matter Physics Ph.D., , Ohio State University.
In nanotechnology: Molecular electronics. The use of molecules for electronic devices was suggested by Mark Ratner of Northwestern University and Avi Aviram of IBM as early as the s, but proper nanotechnology tools did not become available until the turn of the 21st century.
James R. Heath and Mark A. Ratner Molecular Electronics.
modify electronic behavior, providing both switching and sensing capabilities on the single-molecule scale. Dynamical stereochemistry. Many molecules have mul-tiple distinct stable geometric structures or .
The construction of a very simple electronic device, a rectifier, based on the use of a single organic molecule is discussed.
The molecular rectifier consists of a donor pi system and an acceptor pi system, separated by a . Molecular electronics APA.
Jortner, J., Ratner, M. A., & International Union of Pure and Applied Chemistry. (). Molecular attheheels.com Mead, Oxford [England.