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The Newest Solar Technology: a Q and A with Professor Som Mitra

Professor Som Mitra Develops New Solar Cell Technology

Imagine if homeowners could print out plastic sheets of solar cells on inexpensive printers. Imagine further that the solar sheets could be plastered over the roofs of houses and generate electricity – acting in a sense like   mini-power stations for the houses. Such a technology would be an enormous boon to American’s growing environmental movement.

And that is the aim of Somenath Mitra, a professor of Chemistry and Environmental Sciences, who is experimenting with a solar cell derived from polymers that could one day power not only houses but cars, laptops and other consumer computers. Mitra’s solar research was featured in the June 2007 issue of the Journal of Materials Chemistry, published by the Royal Society of Chemistry,

Over the course of his teaching career, Mitra has published 70 journal papers and is the co-author of the book, Environmental Chemical Analysis. He edited another book titled Sample Preparation Techniques in Analytical Chemistry.  He holds five patents and has made more than 150 presentations at academic conferences. In the below interview, Mitra discusses his pioneering solar cell research.

Can you describe your pioneering solar cell research?
Conventional solar cells are made of silicon. But the material that is deposited on the silicon chips cannot be coated. I, however, am experimenting with polymers that when dissolved in a solvent become like a paint, and thus can be used as a coating. You can coat them or print them out on a surface. Developing organic solar cells from polymers is a cheap and potentially simple alternative energy. Solar cells can be inexpensively printed or simply painted on exterior building walls or roofs of houses and buildings. Imagine some day driving in your hybrid car with a solar panel painted on the roof, which is producing electricity to power the engine. The opportunities are endless.

How far advanced is your research?
My research is in the scientific stage, but I’m trying to establish the right chemistry for the polymers. It could take me five years or so to do that. The science goes something like this: When sunlight falls on an organic solar cell, the energy generates positive and negative charges. If the charges can be separated and sent to different electrodes, then a current flows. If not, the energy is wasted. But if you link cells electronically and form what is called a panel, like the ones currently seen on most rooftops, then you've got something.  The size of both the cell and panels vary. Cells can range from 1 millimeter to several feet; panels have no size limits. 

What is unique about your research on solar cells?
The solar cell uses a carbon nanotube complex, which is just a molecular configuration of carbon in a cylindrical shape. The name is derived from the tube’s tiny size. Nanotubes are 50,000 times smaller than a human hair. But one nanotube can conduct a current better than any electrical wire. 

You also use buckyballs in your research.
I and my research team take carbon nanotubes and combine them with tiny carbon buckyballs (a circular-shaped carbon structure) to form snake-like structures. Buckyballs trap electrons, although they can’t make electrons flow. But when you add sunlight to excite the polymers, the buckyballs will grab the electrons. Nanotubes, behaving like copper wires, will then make the electrons or current flow. It’s fascinating.

So once the chemistry is figured out, what are the possible applications of this research?
Theses solar cells, as stated above, will be source of power in which you power appliances, heating and cooling units, laptops, etc. They are a source of power. Someday homeowners will be able to print sheets of these solar cells with inexpensive home-based inkjet printers. They can then slap the finished product on a wall, roof or billboard to create their own power stations. Someday, I hope to see this process become an inexpensive energy alternative for households around the world.

(By Robert Florida, University Web Services)