An international team of scientists has demonstrated for the first time that it is possible to generate a measurable amount of electricity in a diode directly from the coldness of the universe.
The infrared semiconductor device faces the sky and uses the temperature difference between Earth and space to produce the electricity. In contrast to leveraging incoming energy as a normal solar cell would, the negative illumination effect allows electrical energy to be harvested as heat leaves a surface.
Shanhui Fan, an author on the paper responsible for presenting the concept, said, "In terms of optoelectronic physics, there is really this very beautiful symmetry between harvesting incoming radiation and harvesting outgoing radiation."
Today's technology, though, does not capture energy over these negative temperature differences as efficiently.
By pointing the device towards space, where temperature approaches mere degrees from absolute zero, the group was able to find a great enough temperature difference to generate power through an early design.
Masashi Ono, another author on the paper, explained, "The amount of power that we can generate with this experiment, at the moment, is far below what the theoretical limit is."
Calculations made after the diode created electricity showed that, when atmospheric effects are taken into consideration, the current device can theoretically generate almost four watts per square metre, roughly 1 million times what the group's device generated and enough to help power machinery that is required to run at night.
By comparison, today's solar panels generate 100 to 200 watts per square metre.
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