What's boiling up in technology - the WEF vision - VII. Perovskite Solar Cells

A typical perovskite molecular structure. Credit: Texas Tech

Solar cells are now ubiquitous and their efficiency has somehow levelled out at around 25%. WEF has included perovskite among its 10 most impactful technologies in 2016 for their promises to increase significantly the efficiency of solar cells. Indeed perovskite based solar cells are easier to manufacture than silicon based cells, can be used anywhere (no temperature constraints) and keeps getting more efficient.

>>> Perovskite is a mineral discovered in the XIX century in the Ural mountains, based on calcium-titanium oxide aggregated in a special architecture. This same architecture can be replicated using different materials, like tin, lead, aluminium. In 2009 it was discovered that this particular molecular structure can be used to transform light into electricity with an efficiency of 3.8% (pretty low!) although it remained stable (it worked) for just a limited time. 

In 2012, at Oxford, researchers had a breakthrough managing to stabilise the compound and at the same time increase its efficiency. In 2016 perovskite based solar cells have reached a 22% efficiency (result obtained by EPFL researchers and announced in June 2016). At this level of efficiency perovskite based cells becomes better than silicon based solar cells, hence its inclusion in the ten most impactful technologies in 2016 by WEF makes a lot of sense.

Besides, whilst silicon based solar cells seems to have reached an efficiency plateau (although some way to boost their efficiency using solar concentrators are being studied), perovskite based solar cells keeps getting more efficient and there is a consensus that an efficiency around 33% is now within reach (the theoretical maximum efficiency limit has been calculated in 44%). Given the lower manufacturing cost it is a no brainer to predict their success. However, presently, the perovskite structure makes use of lead, that is an environmental poison, and this is stymieing its success.

Author - Roberto Saracco

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