Epoxy resin solves solar tech pollution problems


Addition to perovskite cell manufacture makes them environmentally friendly. Andrew Masterson reports.


Perovskite solar cells are cheap, durable and efficient, but their lead content currently restricts wide-scale use.

Ashley Cooper/Getty Images

The addition of a specially designed polymer could solve one of the major problems associated with perovskite solar cell (PSCs) technology, researchers reveal.

PSCs are made from a hybrid of organic and inorganic metal halide and represent a highly promising avenue for the development of low cost and highly efficient renewable energy generation.

Improvements in manufacture in the past few years have seen the cells reach efficiencies of 22%, making them as efficient as the more common, but costlier, silicon-based technologies.

However, significant problems persist, not the least of which is the tendency of the cell matrix to sustain damage during storm events and consequently leak lead into the environment.

"Although PSCs are efficient at converting sunlight into electricity at an affordable cost, the fact that they contain lead raises considerable environmental concern," explains Yabing Qi, of the Okinawa Institute of Science and Technology in Japan.

Qi and his colleagues, however, may have come up with a solution.

In a paper published in the journal Nature Energy, they outline the addition of a protective layer of “self-healing” epoxy resin to the surface of PSCs.

To test its efficacy, the researchers recreated an extreme weather event in the laboratory – smashing the cells with a hammer to approximate heavy hail, then dousing the remnants in acidic water to simulate polluted rains.

The cells coated with the epoxy, they reported, leached lead at an order of magnitude less than the uncoated controls. This was largely because its molecular structure, when deformed by force, partially reconfigures when exposed to sunlight, or heat.

“Epoxy resin is certainly a strong candidate, yet other self-healing polymers may be even better,” explains Qi.

“At this stage, we are pleased to be promoting photovoltaic industry standards, and bringing the safety of this technology into the discussion. Next, we can build on these data to confirm which is truly the best polymer.”

Lead-free variants of PSCs are available, but their efficiencies are presently much lower than the lead-containing versions.

A study published in the journal Nature Communications early in 2019 reported that they are “plagued with the critical issues of low efficiency and poor stability”.

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5978106/
  2. http://dx.doi.org/10.1038/s41560-019-0406-2
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6318336/
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