Jun 22 2009

Living in a Material World

Posted by: Jonathan Marshall

Pundits point to computers, wireless, the Internet, the Web and now clean tech as the revolutionary technologies of our time. But a strong case can be made that the enabling innovations behind most of those revolutions have been in the field of materials science.

Like Rodney Dangerfield, materials science--the study of the relationship between the atomic or molecular structure of matter and its macroscopic properties--doesn't get much respect outside of narrow professional circles. But the accelerating discovery of new materials with extraordinary properties is what makes advances in solar cells, lithium batteries and terabyte-level computer storage possible. They will be critical to helping the world achieve higher standards of living while using or producing energy more efficiently.

You won't see many stories in your local newspaper, but one of the hottest research areas for materials scientists is a two-dimensional crystalline form of carbon called graphene. A mere one-atom thick, it nonetheless manages to be the strongest material ever discovered. Unlike buckyballs or carbon nanotubes, which are also one atom thick, graphene lies flat, in sheets.

"In physics today, graphene is, arguably, the most exciting topic," says Tomás Palacios, assistant professor in MIT's Department of Electrical Engineering and Computer Science.

It usually behaves like a highly conductive metal, but scientists at Lawrence Berkeley National Laboratory have discovered a reliable way to make it act like a semiconductor (the basis of transistors), by doping it with the right chemicals. The new results make graphene a promising candidate for nanoelectronics (microelectronics is so 20th century) and "could enable new kinds of optoelectronic devices for generating, amplifying, and detecting infrared light," according to the lab's announcement.

Meanwhile, scientists at the University of Manchester have used graphene to create the world's smallest transistors--a mere one atom thick and 10 atoms wide. And at MIT, scientists have shown the ability of graphene to process electrical signals at frequencies a hundred times faster than normal semiconductors, opening up new windows for communications.

An Austin, Texas startup, Graphene Energy, hopes to use the miracle substance to make super high capacity ultracapacitors, which story energy electrostatically between two charged plates, rather than chemically as in batteries. Unlike batteries, ultracapacitors can charge and discharge millions of times without failing. Graphene-based ultracapacitors could have application in electric vehicles, forklifts or even for stabilizing electrical grids.

Because ultrathin graphene films are both transparent and highly conductive, they also show great promise as electrodes in solid-state solar cells. Graphene can also be used for touchscreens, light-emitting diodes, sensing gas molecules and even detecting microbes.

Research in the field was opened up in 2004 when a team of physicists at the University of Manchester first announced their production of graphene. (Their paper almost didn't get published because its claims were so exotic.) 

Highly impractical physicists love the stuff because it lets them explore theoretical questions of particle physics and even astrophysics in their labs without the need for multi-billion dollar particle colliders. The rest of us practical folks can look forward to a host of potentially life-changing applications.

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