I did the procedure described by saliba ( Article How to Make over 20% Efficient Perovskite Solar Cells in Reg...
) to make n-i-p PSCs. However, after perovskite deposition stains appeared in the cell (either in planar and mesoporous configuration). We tried making UV/ozone before depositing the mesoporous or perovskite layer, and the stains still appeared.Does someone know the cause of there stains?
Thank you
Dear Ana
Firstly your films are not homogenous. Did you use the spin-coating technique for your films? We can see the coated trace from either the chuck on the coated or spinning traces.
Secondly some dots on the films are likely from some particles in the solutions. Whether did your materials completely dissolved in the solvents?
For the spincoating problem, you can adjust your spincoating speed, duration and accelerated rate to overcome the traces or stains on the films.
Hope it helps.
Best wishes from Xuhua
Hello Xuhua,
Thank you for your answer! Yes, we deposit the perovskite layer through the one-step via anti-solvent method.
The perovskite solution we obtain is crystal clear, so I think the materials are completely dissolved.
We use the spincoanting program described by Saliba et al, but we can change to see if the stains disappear.
But what do you think about the purity of the perovskite precursors (PbI2, PbBr2, MABr and FAI)? They are stored inside the glovebox, but we have to take them out to weigh them. Do you think they absorb moisture?
And also, do you think these not high purities will significantly affect cell's performance?
- PbI2: 99 %
- PbBr2: 99.999 %
- FAI: 90-100 %
- MaBr: 90-100 %
Finally, do you think it is crucial to have a constant nitrogen flux inside the glovebox during the perovskite deposition?
Thank you so much for your help!
Ana
Dear Ana,
When you weigh your materials in the air, the moisture for sure can be absorbed by your materials. Make sure you could do ASAP to minimise the impact. The impurities in your materials definitely can affect the film quality to some extent, but most of important is to affect your cell performance and stability significantly.
Second point in your question is regarding your nitrogen filled glovebox when you do deposition by the solution processed technique, the constant flux nitrogen will help remove moisture or solvents quickly.
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