12 Dec 2014 Nano-Hype and PV-Hype
Am I the only one to be exasperated by the hype constantly being generated by "nano" and by "PV" (photovoltaics, solar cells)?
I've been especially exasperated by the recent hype over "spray-on solar cells" which seems to me to combine the worst of both hypes. The specific science doesn't concern me here. It's no doubt jolly good as science. It's the hype that bugs me.
Researchers (rightly) get excited about any new effect that can generate some volts over a 1cm2 of test sample with some respectable efficiency. The problem is that scaling up from 1cm2 to 1GW of installed capacity (the only thing that's going to make a significant difference to the planet) is generally impossible for most of these lab ideas. Never mind the problems of stability to heat, light, moisture over a 20+ year lifetime. The real challenge is actually getting the power out of a cell. This sounds trivial - until you try to do it. You have to have some very good conductor on the non-sun side and if your PV coating is just a few 100nm thick (as many of the interesting nano-PV systems are) then this conductor has to be smooth to a few nm, otherwise you get short circuits through the film. This is easy to do on a gold-sputtered glass for a 1cm2 test piece but essentially impossible in the real world.
Even worse, you have to have some sort of transparent conductive system on top of your 100nm of nanostuff. Unfortunately even the best ITO is nowhere near conducting enough to extract the large currents that panels should produce. So you need silver which, of course, is not transparent. So you have to have some compromise with silver "bus bars" and transparent conductors like ITO or PEDOT:PSS. Again the question is how do you put these down onto your 100nm nanostuff, day after day, kilometre after kilometre?
My heretical view is that all research on fancy PV layers should stop and wait till someone's found the right, generic solution for extracting current from fancy nanolayers. Once that's been done then all the players with fancy layers know that their system has to be compatible with the extraction methodology. This will kill the majority of PV ideas which stand no chance anyway and would focus resources on ideas that could really make it big. People working on green technology have to realise that there is a limit to our resources. 99% of PV research away from the mainstream is a waste of resource because those 5% efficiency 1cm2 devices will never see (literally) the light of day.