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Current issue

ELEKTRO 2/2018 was released on February 14th 2018. Its digital version will be available on March 12th 2018.

Topic: Electrical devices; Devices for smart grids; Internet of Things

Main Article
Power flow control in grid using power converters

SVĚTLO (Light) 1/2018 was released on February 5th 2018. Its digital version will be available on March 5th 2018.

Architectural and scenic lighting
Mexican light
Lighting design in a nutshell – Part 34
Lighting technology documentation – part 2 Schemes for scenic lighting

Luminaires and luminous apparatuses
NITECO LED luminaires – guarantied lifespan and warm white light not only for public lighting

Researchers first to create a single-molecule diode

27.05.2015 | PHYS.org | phys.org

Under the direction of Latha Venkataraman, associate professor of applied physics at Columbia Engineering, researchers have designed a new technique to create a single-molecule diode, and, in doing so, they have developed molecular diodes that perform 50 times better than all prior designs. Venkataraman's group is the first to develop a single-molecule diode that may have real-world technological applications for nanoscale devices.

With electronic devices becoming smaller every day, the field of molecular electronics has become ever more critical in solving the problem of further miniaturization, and single molecules represent the limit of miniaturization. The idea of creating a single-molecule diode was suggested by Arieh Aviram and Mark Ratner who theorized in 1974 that a molecule could act as a rectifier, a one-way conductor of electric current. Researchers have since been exploring the charge-transport properties of molecules. They have shown that single-molecules attached to metal electrodes (single-molecule junctions) can be made to act as a variety of circuit elements, including resistors, switches, transistors, and, indeed, diodes. They have learned that it is possible to see quantum mechanical effects, such as interference, manifest in the conductance properties of molecular junctions.

Since a diode acts as an electricity valve, its structure needs to be asymmetric so that electricity flowing in one direction experiences a different environment than electricity flowing in the other direction. In order to develop a single-molecule diode, researchers have simply designed molecules that have asymmetric structures.

Their results achieved rectification ratios as high as 250: 50 times higher than earlier designs. The "on" current flow in their devices can be more than 0.1 microamps, which, Venkataraman notes, is a lot of current to be passing through a single-molecule. And, because this new technique is so easily implemented, it can be applied to all nanoscale devices of all types, including those that are made with graphene electrodes.

Wohle article at Phys.org
Image Credit: Latha Venkataraman, Columbia Engineering