Last updated January 24, 2018 at 2:22 pm
Scientists may have solved the longstanding problem of energy loss in conversion of light to electricity. Are these perovskites the game changer?
Solar efficiency adds to the week’s good news science stories. Credit: EzumeImages/iStock
This week, the International Renewable Energy Agency forecast that renewable energy is going to be consistently cheaper than fossil fuels by 2020.
Solar energy will make up a sizable percentage of this renewable infrastructure but if you think that all the hard work is done, you’d be wrong.
There’s still plenty of room to improve solar cells and one research group recently stumbled upon an answer to a long standing problem.
Scientists from University of Groningen are working on maximising solar cell efficiency by capturing the energy normally lost during the conversion of light to electricity.
“This energy loss puts a limit to the maximum efficiency of solar cells,” said lead scientist from the University of Groningen, Maria Antonietta Loi.
They have created a new material based on perovskites – which, if you don’t know about them, have been touted as the next big thing in solar cell technology.
The new perovskite material slows the loss of the energy from “hot electrons” that are generated when an electron receives more energy than it needs to be extracted as electricity.
Hot electrons your cup of tea?
Think of hot electrons as cups of tea you’ve put in the microwave for too long. You have to wait for it to cool down before you can drink it. Think of all that wasted energy!
The scientists were tackling another challenge with solar cells when they made the discovery.
They were fabricating an environmentally friendly version of a perovskite solar cell which contained tin instead of lead.
But when they analysed their results, something interesting caught their eye.
“The results could only mean that the hot electrons produced in the tin-based solar cells took about a thousand times longer than usual to dissipate their excess energy” said Loi.
Hot electrons normally lose all the excess energy incredibly fast and by creating longer-lived hot electrons the scientists say that this could double the efficiency of perovskite solar cells from a maximum theoretical efficiency of 33% to 66%.
“The hot electrons gave off their energy after several nanoseconds instead of some hundred femtoseconds. Finding such long-lived hot electrons is what everybody in this field is hoping for” says Loi.
While this is an important step for solar cells, the actual mechanism which slows the energy loss from hot electrons will need to be studied further which could result in more super-efficient solar cells.
The researchers are optimistic about the impact this new material will have on solar cell efficiency and their part in a completely renewable energy future.
“These tin-based perovskites could be a game changer, and could ultimately make a big contribution to providing clean and sustainable energy in the future” said Loi.
The study was published in Nature Communications.
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