Researchers at Boston College and MIT have used nanotechnology to achieve a major increase in thermoelectric efficiency, a milestone that paves the way for a new generation of products - from semiconductors and air conditioners to car exhaust systems and solar power technology - that run cleaner.

The team's low-cost approach involves building tiny alloy nanostructures that can serve as micro-coolers and power generators. The findings represent a key milestone in the quest to harness the thermoelectric effect, which has both enticed and frustrated scientists since its discovery in the early 19th century. The effect refers to certain materials that can convert heat into electricity and vice versa. But most materials that conduct electricity also conduct heat, so their temperature equalizes quickly. In order to improve efficiency, scientists have sought materials that will conduct electricity but not similarly conduct heat.

Using nanotechnology, the researchers at BC and MIT produced a big increase in the thermoelectric efficiency of bismuth antimony telluride - a semiconductor alloy that has been commonly used in commercial devices since the 1950s - in bulk form. The success using the relatively inexpensive and environmentally friendly alloy in bulk form means the discovery can quickly be applied to a range of uses, leading to higher cooling and power generation efficiency. Boston College physicist Zhifeng Ren, one of the leaders of the project, said: "This method is low cost and can be scaled for mass production." The research was supported by the Department of Energy and by the National Science Foundation, reveals the institute’s press release.