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Thermoelectric power generators that make electrical power from waste heat would be a useful tool to reduce greenhouse gas emissions if it weren't for a most vexing problem: the need to make electrical contacts to their hot side, which is often just too hot for materials that can generate a current.

The heat causes devices to fail over time.

Devices known as transverse thermoelectrics avoid this problem by producing a current that runs perpendicular to the conducting device, requiring contacts only on the cold end of the generator. Though considered a promising technology, the materials known to create this sideways voltage are impractically inefficient—or so scientists thought. 

Ohio State University researchers show in a new study that a single material, a layered crystal consisting of the elements rhenium and silicon, turns out to be the gold standard of transverse thermoelectric devices.

The scientists demonstrated that this single compound functions as a highly effective thermoelectric generator because of a rare property: simultaneously carrying both positive and negative charges that can move independently rather than running parallel to each other, which forces them to zig-zag their way to the contacts to generate an electrical current.

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