Blooming antennas

In full bloom: A scanning electron microscopy image produced by Jessica Wang of a vertical tetraanaline semiconductor crystal. Credit: UCLA

Amazing how science can, sometimes, be so romantic...

Scientists at the California NanoSystems Institute at UCLA have created a conductive polymer that can be grown vertically to produce an antenna able to capture light coming from any direction.

In the last ten years researchers have been exploring various ways to replace silicon electronics with carbon based electronics for its latter promises of lower energy consumption and better conducting characteristics. Graphene is now on the workbenches in many labs around the world and it is expected that we are going to see the first chips, graphene based, in the next decade, although a full displacement of silicon is not likely for several more years.

What is likely to happen is to have carbon based electronics entering in a few niches. This is the case for this result obtained by growing on a graphene layer polymer of a composite, tetraaniline.  A polymer is basically a long chain of atoms forming a molecule. Tetraaniline form conductive crystals joined one another that stick out from the graphene layer like poles (or flowers from a field, look at the image where the tip, the flower, has been rendered in colour). 
Scientists have discovered a way to grow these "flowers" creating a field of conductive material that could be used as a photovoltaic panel (this in theory, it still has to be demonstrated in practice). 

The advantage of this 3D structure is in the possibility of harvesting light beams incoming from several directions. In today's photovoltaic panels the active surface is flat and can harvest only light beams hitting it from above (and only those having an incidence angle close to 90°, quite a bit of research has been going on to increase the effectiveness of rays hitting at different angles).

The properties of the tetraaniline polymer are tied to the ways the crystals are connected one another. By changing the connection one can create an antenna to absorb light and convert it into electricity or they can be used to emit light (the reverse process, using electrons to generate photons).

What researchers at UCLA did was to find a way to finely tweak a solution of crystals to have them growing in the right pattern to have the desired properties. And at the same time they came up with a blossoming meadow...

You may also want to read the announcement from iBM on a new way to use carbon nanotubes to scale down on transistor size at the level of 1.8nm.

Author - Roberto Saracco

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