Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo


Unsupported browser: Your browser does not meet modern web standards. See how it scores »

{ action.text }

Inside fossil-fuel and nuclear-power plants, as well as in cars and trucks, the lion’s share of energy in fuel is wasted as heat rather than converted into electricity or mechanical power. But the search for a practical material that can convert at least some of this waste heat into electricity has been long and frustrating.

Researchers have long known that some inorganic semiconductors can do this. Indeed, deep-space probes have been powered by using such materials. But these inorganic materials are costly and difficult to make, and have low efficiencies. Now, new research shows that certain organic molecules produce voltage when exposed to heat. Ultimately, they could be much cheaper and thus more practical to implement.

“This is the first demonstration that you can use organic molecules in this kind of energy generation,” says Rachel Segalman, professor of chemical engineering at the University of California, Berkeley, who with her colleagues reported new measurements last week in Science Express. “That’s really significant because they are so inexpensive and abundant,” she says.

Experts had previously theorized that some organic molecules could have the qualities necessary to generate electricity from heat. But until now, they lacked experimental proof, which the Berkeley researchers were able to provide by isolating and measuring the properties of just a few molecules of organic substances called benzene dithiols at a time.

These were “very difficult experiments,” says Brian Sales, a senior research scientist at the Oak Ridge National Laboratory, who was not involved with the work. The researchers trapped a few molecules between a sheet of gold and the ultrafine gold tip of a scanning tunneling microscope, which is so sharp it can end in a single atom. They heated up the gold surface and measured, via the microscope tip, the voltage that was created. “These are the type of difficult experiments that get nanotechnology past the ‘picture’ stage [and] into the realm of real science,” Sales says.

The experiments showed that the organic molecules have the three qualities that make for good thermoelectric materials. The first is the ability to create a voltage. But this works best when the materials have two other qualities: they do not conduct heat, but they do conduct electrons. That way, applying heat, rather than just raising the temperature of the material, actually drives electrons, creating a current.

18 comments. Share your thoughts »

Credit: Image By: Ben Utley and Courtesy of Arun Majumdar.

Tagged: Energy, electricity, efficiency, thermoelectrics

Reprints and Permissions | Send feedback to the editor

From the Archives


Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me