Ramsey, I have been pondering the PR for a few day
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Posted On: 09/21/2018 5:38:01 PM
Re: Puravida19 #10489
Ramsey, I have been pondering the PR for a few days now as there are many things unsaid in it - and have had to take a crash course in Perovskite, something I have not done previously because of my prejudice based on its historical lack of stability and longevity.
It is not said whether the PQD are lead-free or not. Have we now moved to the 'a little lead under RoHS' won't hurt anyone sales camp? My reading is the amount of lead is under the allowance guidelines, and the increased efficiency means less overall active material is used in a display so it is not a concern except for marketing perhaps. The PR did not say "lead-free".
Cadmium has been used in solar cells for a long time by First Solar. Are their solar panels banned anywhere because of that? Is there a double standard for solar vs display use of these metals? I believe there is, and Perovskite PV might be very acceptable while not so in displays. We'll see. If the performance and cost are so much better than existing materials, there could be a strong push for acceptance.
QMC intends to inkjet materials onto both display and PV films. The QD are in a polymer/monomer solution which hardens and encases them rendering them inert. The plastic substrates have to be environmentally resistant for many years use. There is little chance of toxic materials leaching out unless the package is damaged somehow. Other considerations need to be addressed such as recycling. The fact that QDSC can be very lightweight and transportable might mean they are easier to recycle and transform old polymer films into something new like Ikea furniture. This article discusses the environmental problems of recycling displays or solar cells - http://energypost.eu/if-solar-panels-are-so-c...xic-waste/
A Google search of "Perovskite" returned 4 million hits.
A Google search of "Perovskite Vapor" returned over 400K hits
A Google search of "Perovskite Inkjet" returned only 65000 hits
Inkjet is a recent advance in Perovskite technology. Common deposition methods are vapor deposition and spin coating. Typical layers of Perovskite are 250-450nm by vapor as opposed to under 100nm by inkjet.
The following are my guesses based on reading between the lines in the PR. It is pure speculation on my part and I offer it for what its worth, and welcome discussion.
One term frequently repeated in the PR that I have never seen before is 'high-purity', as in 'extremely high-purity PQDS with significantly improved stability.' What does high-purity mean? First, I find it repeated in Perovskite literature as a desirable feature and one that is challenging to accomplish. That is why I have not heard it before. Terms I have heard are 'uniform' and 'selectivity' and I think they are equivalent to high-purity. Desirable characteristics of Perovskite include that they be a perfect cubic structure (selectivity for high quantum yield) and same uniform size (for narrow FWHM for color purity). Both characteristics are very typical of QMC continuous flow process synthesis.
If you examine TEM images of vapor-deposition Perovskite you will see an amorphous mass of layers of perovskite. The perovskite butt up against each other forming a rough lattice and layers of material, as I said, between 250 to 450nm in depth.
Here is something unsaid which seems singular and revolutionary -
Inkjetable quantum dots have to be applied using a liquid medium, typically a
polymer or monomer. You can't inkjet a mass of QD together, each has to be a separate unit. It seems that QMC Perovskite QD are made similar to all their other QD, and far different from typical perovskite synthesis processes. So, each PQD can be shelled like any other QMC QD, and it is then protected from both becoming unstable or degrading, and its longevity is assured just like the candy coating on an M&M prevents the chocolate from melting in your hands. That is revolutionary for PQD IMO.
It is not said whether the PQD are lead-free or not. Have we now moved to the 'a little lead under RoHS' won't hurt anyone sales camp? My reading is the amount of lead is under the allowance guidelines, and the increased efficiency means less overall active material is used in a display so it is not a concern except for marketing perhaps. The PR did not say "lead-free".
Cadmium has been used in solar cells for a long time by First Solar. Are their solar panels banned anywhere because of that? Is there a double standard for solar vs display use of these metals? I believe there is, and Perovskite PV might be very acceptable while not so in displays. We'll see. If the performance and cost are so much better than existing materials, there could be a strong push for acceptance.
QMC intends to inkjet materials onto both display and PV films. The QD are in a polymer/monomer solution which hardens and encases them rendering them inert. The plastic substrates have to be environmentally resistant for many years use. There is little chance of toxic materials leaching out unless the package is damaged somehow. Other considerations need to be addressed such as recycling. The fact that QDSC can be very lightweight and transportable might mean they are easier to recycle and transform old polymer films into something new like Ikea furniture. This article discusses the environmental problems of recycling displays or solar cells - http://energypost.eu/if-solar-panels-are-so-c...xic-waste/
A Google search of "Perovskite" returned 4 million hits.
A Google search of "Perovskite Vapor" returned over 400K hits
A Google search of "Perovskite Inkjet" returned only 65000 hits
Inkjet is a recent advance in Perovskite technology. Common deposition methods are vapor deposition and spin coating. Typical layers of Perovskite are 250-450nm by vapor as opposed to under 100nm by inkjet.
The following are my guesses based on reading between the lines in the PR. It is pure speculation on my part and I offer it for what its worth, and welcome discussion.
One term frequently repeated in the PR that I have never seen before is 'high-purity', as in 'extremely high-purity PQDS with significantly improved stability.' What does high-purity mean? First, I find it repeated in Perovskite literature as a desirable feature and one that is challenging to accomplish. That is why I have not heard it before. Terms I have heard are 'uniform' and 'selectivity' and I think they are equivalent to high-purity. Desirable characteristics of Perovskite include that they be a perfect cubic structure (selectivity for high quantum yield) and same uniform size (for narrow FWHM for color purity). Both characteristics are very typical of QMC continuous flow process synthesis.
If you examine TEM images of vapor-deposition Perovskite you will see an amorphous mass of layers of perovskite. The perovskite butt up against each other forming a rough lattice and layers of material, as I said, between 250 to 450nm in depth.
Here is something unsaid which seems singular and revolutionary -
Inkjetable quantum dots have to be applied using a liquid medium, typically a
polymer or monomer. You can't inkjet a mass of QD together, each has to be a separate unit. It seems that QMC Perovskite QD are made similar to all their other QD, and far different from typical perovskite synthesis processes. So, each PQD can be shelled like any other QMC QD, and it is then protected from both becoming unstable or degrading, and its longevity is assured just like the candy coating on an M&M prevents the chocolate from melting in your hands. That is revolutionary for PQD IMO.
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