A team lead by researchers at the University has found that the lead in solar cells, which is toxic, may be able to be replaced by tin.
Lead-free perovskite solar cells promise to be cheap and easy to mass produce and have already achieved a 17% efficiency at turning sunlight into electricity after just two years of research.
‘Perovskite’ is the term for a particular mineral crystal structure, most commonly a calcium titanium trioxide mineral, but the term is applicable to anything else with the same kind of structure.
In a paper to be published in the journal Energy & Environmental Science, the researchers report that they have created the first lead-free perovskite solar cell. Previous experiments with lead perovskite cells had shown them to be quite efficient.
Nakita Noel, of the University’s Department of Physics, said, “The amount of lead in perovskite solar cells is actually quite tiny. However even in small quantities, the toxicity of the lead could be a barrier to commercialization and as such we’ve started looking into different non-toxic elements to incorporate into the solar cell.”
Tin has been reported to work in pervokskites before, but not in solar cells, which is why their use in this way is so innovative. The metal is completely non-toxic and is capable of carrying a high charge of electricity which make it great for use in solar cells.
The technology is not without its current problems, however, as tin perovskites are unstable in the form in which they are used in the solar cells. This means that when the tin comes into contact with moisture or oxygen it reacts to form a more stable compound, which destroys its charge neutrality and causes the structures inside the solar cell to break down. The team of scientists are currently working on ways to prevent this oxidation.
A mathematician at Exeter College, said, “I think that it would be great if they can get this to work better in the long term. If they can make solar cells more efficient, people would see them as a decent alternative to fossil fuels.”
Nakita Noel agrees, saying, “Hopefully our research will cause a bit of a stir in the academic community and prompt more research into lead-free, more environmentally friendly solar cells. It certainly opens up more avenues for the development of perovskites using different metals. Who knows, we may even find something that surpasses the efficiency of silicon cells.”
