Using solar vitality could also be higher for the surroundings than burning by means of fossil fuels, however the course of nonetheless isn’t precisely excellent. Making silicon-based solar panels is energetically costly and we nonetheless don’t know what to do with the silicon as soon as the panels are carried out getting used.
There is a less expensive way to make solar panels, additionally referred to as photovoltaics (PVs), utilizing crystal constructions referred to as perovskites. However, perovskite crystals include toxic parts like lead, which wants to be processed rigorously as soon as these solar panels attain the top of their lifespan. And thus far, researchers have had to use toxic natural solvents like dimethylformamide to recycle such solar panels.
A yummy sandwich
Now, in a paper revealed in Nature, scientists have described one other, doubtlessly greener way of coping with the issue. Using a water-based recycling answer, they’ve reported a way to degrade and recycle used perovskite. They have been additionally in a position to get again high-quality perovskite crystals, which may doubtlessly be used once more for making new solar cells.
“It’s kind of a complex chemistry to make the water solution usable and very stable for perovskite recycling, to fully remove the [the use of] organic solvents,” Xun Xiao, a postdoctoral researcher at Linköping University in Sweden and lead writer of the paper, stated.
Perovskite solar cells are made up of a number of layers. The perovskite layer is sandwiched between supplies that may conduct and transport expenses, on this case metallic electrodes and glass sheets.
“People have been very excited about [perovskite PVs] for a decade or more now because very quickly they have been able to achieve very high power conversion efficiencies,” Rhys Charles, a researcher within the chemical engineering division at Swansea University within the UK defined. “So you could deliver an extremely cheap solar energy technology, but there are some things that have been holding the field back.”
Stability is considered one of them: perovskite solar cells have a shorter lifespan.
Improving solar vitality
“Early attempts to recycle these devices have all focused on capturing lead. Now, people are taking a little bit more of a holistic view of it,” Charles continued. “From a circular economy point of view, recycling is also important because they want to capture the major impact materials [that] they use again. “
For a circular economy, the aim is to keep the product — in this case the components of a perovskite solar cell — in use for as long as possible, to minimise waste. This way, if the cells are made again with recycled components, they would have a much lower environmental impact, which means lower emissions and lower cost associated with solar energy generation.
Thus far, the only way to recycle these important materials has been to use toxic organic solvents.
Acids and salts
Dissolving and recycling the lead-containing perovskite layer in water was a major challenge to overcome. For this, the scientists added three key salts to help in the recycling process.
The first salt they added was sodium acetate. The acetate ions bound with the lead ions in the perovskite, making a highly soluble lead acetate that dissolved well in water.
They then added sodium iodide and hypophosphorous acid to help regenerate pure perovskite crystals in their water solution. Sodium iodide contains iodide ions that help repair and restore the degraded perovskite, such that when the solution is cooled, high-quality, pure perovskite crystals re-emerge from the solution.
The acid acts as a long-term stabiliser, ensuring the water solution can be reused and that the quality of the recycled crystals remains high.
‘Solved the problem’
“I’m pleased to see this focus on recycling, remanufacturing, and green chemistry,” stated Matthew Davies, a professor of chemical engineering at Swansea University. “It lays the foundation for perovskite PVs to deliver on their promise as a low-cost, high-efficiency solar technology within a circular economy, avoiding the large-scale waste challenges faced by earlier PV technologies.”
The scientists additionally developed options made from ethanol and ethyl acetate to dissolve different elements of the perovskite solar cell, after which they have been in a position to recycle every part to reuse together with the perovskite crystals. Then they reassembled the solar cell layer by layer and located that the effectivity was virtually the identical as utilizing recent supplies, even after being recycled up to 5 occasions. They have been additionally in a position to re-obtain about 99% of the completely different layers even after a number of rounds of recycling.
“These guys seem to have solved the problem; they seem to be able to use this aqueous system to recycle the cells and make them again with high efficiency,” Charles stated. “If it can be scaled [up] and if it works as well as the paper claims, it could potentially overcome some of the most significant barriers to commercialising perovskites and solve some of the key environmental concerns about the technologies as well.”
Charles additionally careworn the necessity to underpin scientific and industrial progress, particularly when it got here to environmental applied sciences, with life cycle assessments. Life cycle evaluation, he defined, is an strategy to quantify all of the impacts of a expertise throughout its whole life cycle, from the beginning to when one has the ultimate product. “But you can go further,” he stated. “Then you can look at the use phase of the technology and the end-of-life phase as well.”
“I always enjoy it when I see these things underpinned by life cycle assessment, to make sure there aren’t unintended consequences and to make sure the research really is targeting the key environmental problems for the technology,” Charles added. “I’d like to see more of that as well, as just standard practice.”
Rohini Subrahmanyam is a contract journalist in Bengaluru.
Published – April 21, 2025 05:30 am IST
