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https://www.chemistryworld.com/features/...19.article

EXCERPTS: Since perovskite solar cells were first reported in 2009, their record efficiency has gone from 3.8% to over 25%. Scarcely a week passes without a breakthrough unveiled in stability, efficiency or applicability. The world is awash with perovskite start-ups and spin-outs from top universities. And yet if you try to buy solar cells for a rooftop or campervan, you will be offered only silicon or perhaps less efficient thin film alternatives. Now the commercial launch of perovskite solar cells is planned this year, and the question of whether they will bear the burden of expectation becomes ever more urgent.

[...] Perovskites ... attract the photovoltaics community for many reasons. Perhaps most importantly, they are easily made by crystallisation from solution. This doesn’t produce defect-free films, but it doesn’t need to. ‘These materials are almost entirely ionic,’ says Snaith. ‘When you have a defect, the energy of that defect is close to or in the continuum of states. The consequence is that we can have a very high density of crystal defects but they work very well for a solar cell.’ Moreover, the perovskites of interest are often made entirely from Earth-abundant materials, with 10TW installation requiring just a few days of lead production, for example.

Perovskites are also extremely attractive for ‘tandem’ solar cells, comprising sequential layers with different bandgaps to make more efficient use of broad-spectrum light...

[...] The main obstacles to perovskites’ commercialisation, however, have been instability issues...

[...] With multiple groups trying to push various perovskite solar cell designs from the laboratory to the market, it becomes increasingly important to develop standardised methods to compare their long-term durability. Extrapolating how long a perovskite solar cell will last, however, is tricky. There is no perovskite-specific ‘accelerated ageing’ test because no-one truly knows how perovskite solar cells will degrade after – hopefully – 25 years or more in the field...

[...] Snaith remains bullish, noting that a perovskite research project co-funded by the EU’s Horizon 2020 had conducted an environmental impact assessment on perovskite on silicon tandem cells and concluded that the environmental impact of adding the perovskite was positive...

[...] Asked to name the single biggest issue facing the stability of perovskite solar cells, Snaith laughs. ‘I’ll argue that there is no issue,’ he says; ‘There’s certainly things you need to get a handle on to make the stuff stable. It’s very easy to make unstable perovskite solar cells.’ (MORE - missing details)