Hi, guys..
These days, I have some problem in OPV processing.
To be more specific, the active film is OK right after spin casting. But while drying it, the film is getting hazy..... it is changed to be worse.. like an attached picture....
Does anyone know why this problem is happening? or how to solve this probelm?
Please let me know what should I do to solve it....
Hi Jisu,
It is hard to be sure without knowing the materials, but if the whole film got hazy, it suggests some large (~several 100 nm) crystallization or aggregation happens in the mixed BHJs. This process could slowly proceed after deposition of the films. My suggestion is check the films under optical microscopy or AFM. The possible solution could be adding a good solvent in the system (stability of the device may be still the problem, though).
Jisu,
The materials look OK, I would not expect severe crystallization problem. But the haziness means there are some light-diffusive structure in the film, so I recommend you to check the film morphology anyway.
I am sorry but I am not sure about the reason now. If you use the same CF for the fabrications, it would not be the solvent (otherwise, long-stored CF sometimes generates acid, which may change the solubility). Maybe there are specific interaction between the components? If so, it could be interesting:) KT
Hi Jisu,
The large crystallization is due to poor film morphology of the active layer where you have more reflected photons. Decreasing the film thickness or using a different solvent system may help. I also suggest you to check with AFM to understand the multi-components that cause this haziness.
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