In a significant step toward sustainable solar energy, researchers at Linköping University and Cornell University have developed a water-based method to fully recycle perovskite solar cells (PSCs). This innovation eliminates the need for environmentally hazardous solvents while retaining the efficiency and stability of the original solar cells.
Perovskite solar cells have gained traction in the renewable energy sector due to their high efficiency, low-cost production, and lightweight properties. However, recycling and lead toxicity concerns have slowed commercialization, making it difficult for perovskite technology to compete with traditional silicon solar panels.
Feng Gao, professor of optoelectronics at Linköping University and co-author of the study, emphasized the significance of integrating sustainability early in the development of new solar technologies.
"If we don’t know how to recycle them, maybe we shouldn’t put them on the market at all," Gao said.
The Science Behind the Water-Based Recycling Process
Traditional recycling methods for solar panels rely on toxic solvents, such as dimethylformamide (DMF) and chlorobenzene, which pose environmental and health risks. The new approach replaces these solvents with aqueous solutions, making the recycling process safer, cheaper, and more efficient.
The process involves three steps. First, thermal processing is applied by heating the encapsulation layer to 150°C, which softens the protective coatings, allowing for the separation of materials without damage. Then, the perovskite layer is dissolved in a water-based solution containing sodium acetate (NaOAc), sodium iodide (NaI), and hypophosphorous acid (H₃PO₂). This ensures high-purity perovskite recovery. Finally, the solution is cooled to reform the perovskite crystals, which can be reintegrated into new solar cells.
"The biggest challenge was to recover phase-pure and high-quality perovskite crystals from the water solution," said Feng Gao. "We spent quite some efforts to make that happen."
A study published in Nature confirms that 99% of the materials in a perovskite solar cell—including glass, electrodes, perovskite layers, and charge transport layers—can be successfully recycled. Xun Xiao, postdoctoral researcher and co-author of the study, highlighted the novelty of the process:
"We can recycle everything – covering glasses, electrodes, perovskite layers, and also the charge transport layer," Xiao explained.
Efficiency and Economic Viability
A major concern with solar cell recycling is whether the recycled materials can perform as well as new materials. The researchers addressed this by testing the efficiency of the recycled perovskite cells. The results were impressive:
Recycled perovskite solar cells achieved an average power conversion efficiency (PCE) of 21.9%, with a champion efficiency of 23.4%. Even after five rounds of recycling, the efficiency remained nearly identical, with an average of 21.8% and a peak of 23.5%.
Further stability tests showed that 88.2% of the initial efficiency was retained after 504 hours of exposure to air at 85°C, and 87.7% after 552 hours of light soaking at 50°C. These findings indicate that the recycling process does not degrade the performance of perovskite solar cells, making it a viable long-term solution.
Fengqi You, a researcher at Cornell University, conducted a techno-economic analysis and found that implementing this recycling method at scale could significantly reduce production costs.
"Recovering everything from the front glass to the perovskite layer significantly cuts resource use and reduces long-term costs," You said. "This makes perovskite photovoltaics far more competitive."
Environmental Benefits and Lead Neutralization
One of the biggest criticisms of perovskite solar technology is its reliance on lead-based compounds, which can pose a risk of soil and water contamination if not properly disposed of. This new recycling process not only recovers the perovskite materials but also neutralizes lead ions, significantly reducing the toxicity risk associated with perovskite waste.
By diverting perovskite materials from landfills, the process helps mitigate electronic waste accumulation. Compared to landfilling, this method reduces resource depletion by 96.6% and human toxicity impact by 68.8%.
Fengqi You underscored the environmental significance of the breakthrough:
"The minimal energy required for water-based dissolution, combined with the high purity and reuse of recovered materials, led to significant environmental and economic benefits well beyond our initial expectations."
The Future of Perovskite Solar Technology
With the water-based recycling method proven in the lab, the next challenge is scaling it for industrial use. Researchers aim to make the process commercially viable for solar manufacturers and recyclers, ensuring perovskite technology remains both cost-effective and sustainable.
“There are many companies that want to get perovskite solar cells on the market right now, but we’d like to avoid another landfill,” said Xun Xiao. “In this project, we’ve developed a method where all parts can be reused in a new perovskite solar cell without compromising performance.”
By simplifying solar panel recycling, this breakthrough could cut costs, reduce waste, and accelerate clean energy adoption. With large-scale implementation underway, perovskite solar panels are set to reshape the industry. The question is no longer if they will go mainstream, but how soon.
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