I fabricated the pure MAPbI3 perovskite thin films before by spin-coating and Diethyl ether anti-solvent, and I could get some beautiful black and mirror-like perovskite surface. Then I transferred to the recipe with (FAMACS) combination and FA is the main part still with diethyl ether as anti-solvent, but the surface looks foggy and there is a ring in the middle. The thin film could still show a strong PL peak at the expected position, but I am not sure if it is normal for a perovskite layer that could be fabricated to a high-efficiency solar cell?
If strong PL is detected from the active layers of solar cells, the cell efficiency must be very low due to excitons forming PL not current.
I think you'll just have to try it, some features visible by eye make a difference, some don't. In terms of maximum current, the optimum surface is antireflective, i.e. matt (non-shiny) and black. But that changes once you add coatings anyway.
I disagree with the prior comment. As long as your cell is not connected to anything (i.e. at open circuit), strong PL is a sign of good absorber quality.
Foggy sample and the ring is a common problem when the anti-solvent step is still unoptimized. Its a manual step which is very delicant and demands accuracy . Perhaps , i would say to check the quantity you use ( maybe need less) , try dripping process of antisolvent lasting ~ 1s and distance between pippete and sample approximately 1 cm .
Jinze Cai I am also having a similar problem with the formation of the foggy layer and ring at the center. I think Nikolaos Tzoganakis argument is valid. Moreover, I have also observed that FA cation might have some role in assisting the formation of the ring at the center of the film. Since I have not seen ring formation for pristine MAPbI3 based perovskites.
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nanostructures
- Thin Films