During fabrication of perovskite based solar cells; when PbI2 and CH3NH3I dropped onto PEDOT:PSS (HTL) coated ITO substrate, some additional solvent is also dropped onto the film (during spin coating) to do faster crystallization. Now question arises, what is the Solvent Induced Fast Crystallization (SIFCD) method used for fabraication of pervskite based solar cells? How it will affect crystallization of perovskite films? Is this applicable for other HTL/ETL materials?
Dear Hasan,
I would like to greet you for your the interesting series of questions about the perovskite solar cells.
I agree with the answer of Subrata that one needs to increase the supersaturation of the spices in the solution to increase the deposition rate. Subrata gave two methods to increase the supersaturation. The method of antisolvents may increase rapidly the supersaturation of the spices in the solution.
It is so as one increases the supersaturation the rate of nucleation increases and the film will grow more homogeneous with much less pinholes.
As a proposal, you can use rapid thermal annealing.
Best wishes
Dear Hasan Abbas,
Antisolvents are used to induce fast crystallization in perovskite film formation. Antisolvents to perovskite precursors are those solvents which do not dissolve the perovskite precursors. So, upon dripping antisolvents on perovskite precursor film during spin coating, antisolvents create supersatutation condition by displacing the perovskite precursor solvent (DMF/DMSO/GBL etc.). This supersaturation condition leads to fast precipitation/crystallization. Supersaturation conidition arises due to reduction of solubility product by adding antisolvents.
In conventional processing, thermal annealing is needed to evaporate the perovskite precursor solvent to create supersaturation condition. The main disadvantage of the conventional process is degradation of perovskite materials during thermal annealing and incomplete surface coverage by the film formed.
But in antisolvent processing need for a thermal annealing is not must if the boiling temperature of the antisolvent is low. Importantly, antisolvent induces fast cryatallization with homogeneous nucleation throughout the surface that leads to complete surface coverage. Some antisolvents for perovskite precursors are Chlorobenzene, Toluene, Diethyl ether, Dichloromethane etc.
For further study read the articles provided
1.Article A Fast Deposition-Crystallization Procedure for Highly Effic...
2. https://www.nature.com/articles/nmat4014
3. https://pubs.rsc.org/en/content/articlehtml/2014/ra/c4ra13212b
4.Article Room Temperature Fabrication of CH3NH3PbBr3 by Anti-solvent ...
Dear Hasan,
I would like to greet you for your the interesting series of questions about the perovskite solar cells.
I agree with the answer of Subrata that one needs to increase the supersaturation of the spices in the solution to increase the deposition rate. Subrata gave two methods to increase the supersaturation. The method of antisolvents may increase rapidly the supersaturation of the spices in the solution.
It is so as one increases the supersaturation the rate of nucleation increases and the film will grow more homogeneous with much less pinholes.
As a proposal, you can use rapid thermal annealing.
Best wishes
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