July 19, 2021

THAT WAS EASY:

Removing the lead hazard from perovskite solar cells (Ecole Polytechnique Fédérale de Lausanne, 7/15/21, Science Daily)
    
"The solar energy-to-electricity conversion of perovskite solar cells is unbelievably high, around 25%, which is now approaching the performance of the best silicon solar cells," says Professor László Forró at EPFL's School of Basic Sciences. "But their central element is lead, which is a poison; if the solar panel fails, it can wash out into the soil, get into the food chain, and cause serious diseases."

The problem is that in most of the halide perovskites lead can dissolve in water. This water solubility and solubility in other solvents is actually a great advantage, as it makes building perovskite solar panels simpler and inexpensive -- another perk along with their performance. But the water solubility of lead can become a real environmental and health hazard when the panel breaks or gets wet, e.g. when it rains.

So the lead must be captured before it gets to the soil, and it must be possible to recycle it. This issue has drawn much and intensive research because it is the main obstacle for regulatory authorities approving the production of perovskite solar cells on a large, commercial scale. However, attempts to synthesize non-water-soluble and lead-free perovskites have yielded poor performance.

Now, Forró's group has come up with an elegant and efficient solution, which involves using a transparent phosphate salt, which does not block solar light, so it doesn't affect performance. And if the solar panel fails, the phosphate salt immediately reacts with lead to produce a water-insoluble compound that cannot leach out to the soil, and which can be recycled. The work is published in ACS Applied Materials & Interfaces.

It's always a bad day to be a Luddite. 

Posted by at July 19, 2021 12:00 AM

  

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