How many rare and/or nasty raw materials do they need though?
Shouldnāt need any - perovskites are a naturally occurring group of Ca-Ti oxides, cation embedding mostly seems to involve other transitional metals close to Ti, so no immediately-obvious need to throw anything scary into the mix.
I hope youāre right (cos thatās well beyond my chemistry) but youāre forgetting companiesā willingness to fuck everything to increase profit
Given that you can buy standard panels with 22% efficiency which last for 25 years now
https://www.sunpowercorp.co.uk/products/maxeon-solar-panels
my flabber remains mostly unghasted for now.
Itās got lead in it which is, technically, toxic. But the active parts are all in thin layers, so each cell only contains a tiny amount of anything. Cadmium sulphide PV cells (obviously) contain cadmium, but so little that when I last looked they could be sold as ācadmium freeā. Even in California. As long as the production plant is well-managed and the much thicker substrate material is harmless (often silicon, sometimes glass, even stainless steel) then you neednāt worry about toxicity.
Weāve had multijunction cells for a long time. IIRC the Mars rovers use them. Hereās one thatās 30% efficient. The trick is to find structures which are cheap and reliable to make, where the production is scalable and where the lifetime is good. Perhaps thatās where the perovskites show promise ?
VB
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The efficiency over lifetime curve is also worth looking at.
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Anything that doesnāt lean too hard on Strategic Materials (esp. rare earths) seems to be part of the motivation. The 30% PVs use all kinds of scary and/or rare stuffā¦
Gallium, arsenic, indium and phosphorus on a silicon substrate. Arsine and phosphine will hurt you if you breathe them but weāve been making semiconductors out of these materials for many decades and we know how to handle them perfectly well. Galliumās not really rare (by-product of bauxite and zinc-ore refining). Thereās as much phosphorus as we want and thereās too much arsenic. Thereās a bit of an issue with indium. Which is a shame because like tin it has a lovely cry when you bend it (I have heard it).
VB
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You are a font of useless, but interesting, information. Long may it continue 
Sounds as if it is throwing up
I remember the indium as sounding nicer than that. I went to a talk once given by Norman Booth who was trying to raise funds for an indium detector for solar neutrinos. The problem was youād need tons and tons of indium. Heād already acquired quite a lot and he brought a bloody great ingot of it along with him (maybe 60cm x 10cm x 10cm). I donāt remember anything about the talk Iām afraid. But I do remember him bending this thing (indiumās very soft) and it letting out a sort of plaintive creaky squeal. Weird.
VB
I have a drawer of old mobile phones that would probably crash the the commodities market were I to recycle them.
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Iāll take that as a compliment 
.
VB
As you should 
He is also a fount of useful knowledge.
This does not make him any less annoying.
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That just comes naturally 
.
VB
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We were in the Liverpool store last week and it had piles of LPs. Being a tight git (and having already spent my allowance for the day) I didnāt buy any but they had hundreds of records
Vinyls 
HMVkuntz
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you will notice I didnt refer to vinyl (singular or plural) in my commentā¦ and it is the grauniadā¦