New device can turn heat energy to fuel

Scientists have developed a device that could turn the heat generated by electronics into a usable fuel source, an advance that may help save energy.
The device is a multicomponent, multi layered composite material called a van der Waals Schottky diode, said researchers at Washington State University (WSU) in the US.
It converts heat into electricity up to three times more efficiently than silicon - a semiconductor material widely used in the electronics industry, they said.
"The ability of our diode to convert heat into electricity is very large compared to other bulk materials currently used in electronics," said Yi Gu, physicist at WSU.

"In the future, one layer could be attached to something hot like a car exhaust or a computer motor and another to a surface at room temperature," said Gu.
"The diode would then use the heat differential between the two surfaces to create an electric current that could be stored in a battery and used when needed," he added.

The diode would then use the heat differential between the two surfaces to create an electric current that could be stored in a battery and used when needed, researchers said.
Instead of combining a common metal like aluminium or copper with a conventional semiconductor material like silicon, the researcher's diode is made from a multilayer of microscopic, crystalline Indium Selenide.

They used a simple heating process to modify one layer of the Indium Selenide to act as a metal and another layer to act as a semiconductor. They then used a new kind of confocal microscope to study their materials' electronic properties.
Unlike its conventional counterparts, the diode has no impurities or defects at the interface where the metal and semiconductor materials are joined together.
The smooth connection between the metal and semiconductor enables electricity to travel through the multi layered device with almost 100 per cent efficiency, researchers said.
"These imperfections trap electrons, impeding the flow of electricity. Gu's diode is unique in that its surface does not appear to have any of these defects," said Matthew McCluskey, physicist at WSU.

"This lowers resistance to the flow of electricity, making the device much more energy efficient," said McCluskey.
The study was published in The Journal of Physical Chemistry Letters.