ScienceFirst practical single-molecule diode created in Columbia University lab by NRI Scientist

First practical single-molecule diode created in Columbia University lab by NRI Scientist

Indian American scientist Latha Venkataraman and her team from Columbia University have created the first ever single molecule diode that can be described as ‘functional’ in the real world. A diode can be loosely called an electricity valve which helps current flow easily in only one direction. A perfect diode would allow zero resistance to current in one direction and infinite resistance in the other.

Venkataraman and her associates have used a new technique to develop a single molecule diode, resulting in it being able to perform 50 times better than what has been achieved till date. This opens up a huge number of application scenarios in the production of nanoscale devices. As technology moves towards miniaturization, the need for such breakthroughs is more pronounced than ever before.

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It’s not possible to go smaller than a single molecule. The problem with typical asymmetric conductance is that there’s not enough difference between the amount of current permitted to flow in both directions. Venkataram’s creation is capable of transporting 0.1 microamps in one direction, while merely enabling 1/250th of this to pass the other way. The details can be read in the paper titled ‘Single-Molecule Diodes with High On-Off Ratios through Environmental Control’, published in the journal Nature.

The concept of building such a single molecule diode was proposed by Arieh Aviram and Mark Ratner in the year 1974. Researchers have been chasing this dream of perfection since then. Venkataram and her colleagues brought about an environmental asymmetry around the molecular junction by submerging the active molecule with an ionic solution. Gold metal electrodes of various sizes were employed to contact the molecule. The combination is a manifestation of ‘functional miniaturization’ that’s practical in the real world.

But Venkataram and her team are obviously not satisfied with their stupendous accomplishment and are working to improve their highly functional single molecule diode. Scientists. What can you say!

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