The School of Photovoltaic and Renewable Energy Engineering at the University of New South Wales (UNSW) in Australia have claimed a breakthrough in generating solar power at night using infrared light from radiated heat.
They used thermoradiative diode, a semiconductor device that's made up of materials found in night-vision goggles, to generate the power. They claim even though it is night time, it is still solar power as the earth absorbs the sunlight from the sun during the day and during the night this same energy radiates back into the outer space in the form of infrared light.
Though they were able to generate around 100,000 times less than that supplied by a solar panel, the researchers are confident of its potential to generate the same at a larger scale in the future with further research. "At a temperature differential of only 12.5 °C, we measure a peak thermoradiative electrical power density of 2.26 mW/m2 for a photodiode emitting near 4.7 μm, with an estimated radiative efficiency of 1.8%, according to the researchers.
UNSW's research paper has found its way into scientific journal ACS Photonics.
"Photovoltaics, the direct conversion of sunlight into electricity, is an artificial process that humans have developed in order to convert the solar energy into power. In that sense the thermoradiative process is similar; we are diverting energy flowing in the infrared from a warm Earth into the cold universe," said one of the paper's co-authors, Dr Phoebe Pearce.
To prove their point, the team refers to the 1st silicon solar cell launched in 1954 whose efficiency was only 2% back then, but modern day cells have an efficiency of around 23%.
""Even if the commercialization of these technologies is still a way down the road, being at the very beginning of an evolving idea is such an exciting place to be as a researcher," said Co-Author of the paper Dr Michael Nielsen. "By leveraging our knowledge of how to design and optimise solar cells and borrowing materials from the existing mid-infrared photodetector community, we hope for rapid progress towards delivering the dream of solar power at night."