Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.
Advertisement
Produced by
With their large temperature differences between day and night, deserts make ideal locations for thermoradiative diodes, which generate electricity when they are hotter than their surroundings.Credit: Lovleah/iStock/Getty
Solar cells are an indispensable plank of the renewable energy transition, but they have an obvious limitation — they are useless at night. To fill this gap, scientists are exploring solar-cell-like devices that could generate electricity by exploiting the conditions at night.
Thermoradiative diodes are like solar cells in reverse. Solar cells generate an electric current by absorbing photons from a hotter object (i.e. the Sun), whereas thermoradiative diodes generate a current by emitting photons of infrared light into colder surroundings. As long as thermoradiative diodes are warmer than their surroundings, they will emit infrared radiation and generate electricity.
Now, power generation from a thermoradiative diode has been demonstrated experimentally for the first time by a team of physicists at the University of New South Wales (UNSW) in Sydney, Australia^1,2,3.
Defying common sense
“It’s counterintuitive that a material that emits radiation can generate electricity at the same time,” says Nicholas Ekins-Daukes, a professor at UNSW’s School of Photovoltaic and Renewable Engineering. “But that’s what we’ve succeeded in demonstrating.”
The amount of electricity that the thermoradiative diode, made from mercury cadmium telluride, generated was low – about enough to power a wristwatch from body heat. However, there’s room to improve performance 1,000 fold before thermoradiative diodes start bumping up against the maximum power permitted by thermodynamics.
Even at those efficiencies, they won’t be able to charge electric vehicles but they could be used to power household devices. “Many people leave their WiFi on overnight and charge their phones,” says Ekins-Dauke, who heads the UNSW Night-Time Solar Team. “There’s a light electrical load at night, which thermoradiative diodes could help supply in the future.”
A photograph of Nicholas Ekins-Daukes’ team taken using an infrared camera.Credit: The University of New South Wales
Powering satellites
A promising application for thermoradiative diodes in the nearer future is supplementing the power of satellites in low-Earth orbits, which typically cycle between 45 minutes of sunlight and 45 minutes of darkness. Laminating a thermoradiative diode on to a spacecraft’s surface could provide auxiliary power during the dark spells.
Ekins-Daukes’ team is working on a project funded by the United States Air Force for just such an application. “One of the project’s objectives is to optimize our thermoradiative diode technology as much as possible and then do a space flight,” he says.
It’s interesting to note that the development of silicon solar cells followed a similar path. They were demonstrated in the lab in 1953, but within five years they were being used in space.
“I’m saying to my team, ‘Those guys didn’t have the benefit of computers — they were working with slide rules and log tables — and they went from lab demonstration to space flight in five years’,” says Ekins-Daukes. “Let’s do the same with thermoradiative diodes.”
Filling in the blanks
In addition to plugging a gap that solar cells can’t cover, thermoradiative diodes fill a blank quadrant in physics textbooks.
In plots of current against voltage for optoelectronic devices, light-emitting diodes (LEDs) occupy the first quadrant (positive voltage; positive current), solar cells the second (positive voltage; negative current), and light detectors the third (negative voltage; negative current). But the fourth quadrant (negative voltage; positive current) is empty. That’s where thermoradiative diodes will fit in.
“The top left quadrant in all the textbooks has always been empty. That’s probably because the notion that electricity can be generated from infrared emission is so counterintuitive,” says Ekins-Daukes. “When I talk to people about it, they often respond: ‘Wow, you mean this is possible? That kind of blows my mind’.”
For more information visit UNSW School of Photovoltaic and Renewable Energy Engineering.
Nielsen, M. P. et al. Nat. Photonics 18, 1137–1146 (2024).
Article  Google Scholar 
Harrison, J. A. et al. iScience 27, 111346 (2024).
Article  PubMed  Google Scholar 
Nielsen, M. P. et al. ACS Photonics 9, 1535–1540 (2022).
Article  Google Scholar 
Download references
Nature Index: Energy
Global dementia collaboration reveals devastating impact of stroke
How cancer cells use mechanical forces to resist treatment
Making stable and sustainable solar power from perovskite cells
The unexpected danger from ‘ember storms’ during severe wildfires
Nature Index: Energy
Global dementia collaboration reveals devastating impact of stroke
How cancer cells use mechanical forces to resist treatment
Making stable and sustainable solar power from perovskite cells
The unexpected danger from ‘ember storms’ during severe wildfires
Nature Research Custom
© 2025 Springer Nature Limited

source