Should I add in 3A molecular sieves into the SnO2 solution with isopropanol added? I am planning to use it on top of perovskite (MAPbI3) layer but the water comes with the SnO2 solution can damage the perovskite layer, so the water has to be removed first
Centrifuge, pour off the water, add IPA, disperse and repeat a few times.
Filter through semi-permeable membranes. Dry under vacuum. Add ispropanol.
Thank you John Francis Miller and Yuri Mirgorod for the suggestions. I just worried that the additives (e.g. surfactant/stabilizers) and the pH comes with the stock solution will be gone if I re-disperse them after washing or drying. I'll try your suggestion. Also, may I ask will the colloids forms aggregate at the bottom of the centrifuge tube after centrifuging them? Will vacuum drying the solution also result in aggregation of the colloids? Thank you again.
Soo Yew Hang Replacing the water with a different liquid will change the pH. Indeed, there will be no pH since there will not be any H+ ions.
Both the centrifugation and filtration options have benefits and disadvantaged. Both require some investigation to optimize the process.
For centrifugation, any surfactants etc that are not attached to the particles will be removed. With filtration, the size of the filter pores and the molecular weight of the surfactants will determine how much, if any, is removed. Simple surfactants are likely to pass through the filter whereas very large polymer surfactants may be retained.
Whether or not centrifugation results in aggregated particles depends on how they are stabilized and other factors such as how big the particles are, their density and how long you centrifuge for.
It is likely that drying will lead to some irreversible aggregation. However, it will remove more water than the centrifugation option. You need to assess the maximum water concentration you can tolerate. If it is, say, 1%, then a few centrifugation/redispersion cycles may work well. If it has to be less than 0.1%, drying may be needed.
Of course, practically, the filter + drying is easier and quicker. Depending on how small and dense your particles are, an appropriate centrifuge could be expensive.
John Francis Miller and Yuri Mirgorod , thank you for this very useful opinion. I am want to deposit the SnO2 ETL layer in inverted perovskite solar cells. Therefore, I cannot use traditional SnO2.2H2O or SnO2.5H20. I want to know can I form a precursor for SnO2 deposition from dissolving anhydrous SnCl2 in Isopropanol with the same solution molarity (0.1 M or 0.2 M)?
Thank you!
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