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I'm a student working in a high school laboratory that is looking to pursue research into perovskite cells for next year, but I have some solubility and safety questions.

What would be a good solvent (please be specific) of copper(I) iodide?, copper(I) thiocyanate? Silver iodide?

I want to deposit these materials out of solution onto the substrate. Christians et al. in 2014 deposited copper(I) iodide from a 1:39 chlorobenzene/di-n-propyl sulfide solution, but my mentors have rejected chlorobenzene as a substance with high environmental toxicity and difficult disposal procedures.

Ideally, the solvent for any of the three compounds would dissolve the compound well, and then evaporate off with heating, while having no to low toxicity.

Additionally, I have received approval for purchasing methylammonium iodide and lead(II) iodide which I will dissolve in gamma-butyrolactone in 1:1 molar. There are no safety sheets for the product, methylammonium lead iodide, so my mentors wanted me to see if there were any harmful properties that would come about from making this compound, ie: is there anything more dangerous or something more to watch for from methylammonium lead iodide than methylammonium iodide or lead(II) iodide?

Article: An Inorganic Hole Conductor for Organo-Lead Halide Perovskite Solar Cells. Improved Hole Conductivity with Copper Iodide

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    $\begingroup$ Lead Iodide is a little nasty, (Iodomethyl)trimethylammonium iodide is okay. I'd say your product should be treated at least as hazardous as Lead Iodide. Chlorobenzene is indeed a pest. $\endgroup$ – Martin - マーチン May 29 '14 at 7:25
  • $\begingroup$ Copper (I) iodide is soluble in pyridine, not idea about silver iodide though. $\endgroup$ – permeakra Jun 29 '14 at 13:05
  • $\begingroup$ @permeakra If the choices are chlorobenzene and pyridine, I'd choose chlorobenzene every time. $\endgroup$ – buckminst Jul 21 '15 at 14:31
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Tell your mentor that to be concerned about chlorobenzene toxicity on perovskites is riddiculous. The most toxic thing in perovskites is the lead iodide...chlorobenzene´s toxicity is much lower than that. If he is so worried about toxicity, he should not work on perovskites.

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Lead is the main toxic factor, if you work in a fume hood and make sure that the solvents used in the process are not going to be inhaled by anyone else and that you wear gloves and wear goggles for protection you are reducing your exposure to the toxic properties of the Lead if absorbed into your skin or accidentally ingested, the reason is this is a very soluble form of Lead. Some might argue lead is used everywhere in the industrial electronics etc but it is the fact that Lead in perovskite solutions and powders is very soluble.

DMF is a solvent that often papers use, quite toxic as is chloroform, need to use them in the fume hood so you don't smell them, their smells are distinct so if you do smell them at least you know that you need to clear up a problem that has been created. When you anneal the perovskite substrate the solvent evaporates and you are left with a film of perovskite crystals. The HTM as you know is also drop casted or spin coated on in most cases and needs to be a solvent that will not react or dissolve the perovskite film.

Most groups use Chloroform and a mixture of others for the different additives for the Spiro HTM (Standard HTM at present) such as TbP. CuI is a HTM that is much cheaper than Spiro and while it is not as good the performance is good enough considering the cost. I just did a google and found https://en.wikipedia.org/wiki/Copper(I)_iodide } that it is soluble in: soluble in ammonia and potassium solutions insoluble in dilute acids I don't know though if those solvents would affect the HTM film after evaporation or spin coating or react with the perovskite film. Let me know or publish if you find they don't in any case while doing it WEAR PROTECTIVE GLOVES AND GOGGLES

The thing about the solvents is something I am not sure of, just make sure that when you do the work you have the relevant safety measures taken, fume cupboard, after using beakers with solvents, wipe/rinse with Acetone and Ethanol then wash the thing that contained your solvent in the relevant area.

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