Dear Firas,

welcome!

What you have is deposited grains on the surface of the glass. They scatter the light as if they are of powder nature on the Glass.

I would propose that you remelt the film and re-solidify it by LASER annealing or by a rapid thermal annealing using radiation heating.

In summary you need post heat treatment which is to remelt and solidify the film. After this process the layer will be transparent.

Best wishes

I think, it is all about hydrophobic or hydrophilic nature of your substrate-solvent combination. It can be characterized with contact angle measurements.

You may try FTO or ITO coated glass or other transparent substrates. The foggy nature mainly depends on how much DMF prefers to get stuck on the substrate under use. So, vary the solvent or the substrate to get rid of it.

When your coating becomes foggy, you observe just crystallization of your metal complex. You may solve your problem by making your coating glassy. This is possible if the compound used for coating is dissolved in the saturated solvent vapors. See, for example, Article Smart Polymorphism of Thiacalix[4]arene with Long-Chain Amid...

Otherwise, you may add to your solution some polymer that prevent crystallization of your complex

drop casting is not the best way to get a good coating (unless, perhaps, in some superhydrophobic cases). You should try, if possible with your materials, spin coating or better spray coating with very small droplets (of the order of few tens of microns diameter).

Souvik Bhattacharjee

Thank you very much for your suggestions .

I have tried but the problem still not solved.

Valery V Gorbatchuk

Thank you very much for your suggestions.

You are right using polymer could solve the problem.

Giuseppe Curro

Dear Souvik Bhattacharjee,

Thank you very much for your suggestions.

I have tried spin coating but the problem still not solved

When you are annealing the film at hot plate cover it with a petri dish. Before that add a few drop of DMF on the inner walls of the petri dish that would be close to the film during annealing. Basically you have to anneal it in DMF atmosphere. Do not exceed temperature over 150 degree C.

Before anneal it, you can also keep it in vacuum for 10 min (it is called aging).

Dear Firas,

welcome!

What you have is deposited grains on the surface of the glass. They scatter the light as if they are of powder nature on the Glass.

I would propose that you remelt the film and re-solidify it by LASER annealing or by a rapid thermal annealing using radiation heating.

In summary you need post heat treatment which is to remelt and solidify the film. After this process the layer will be transparent.

Best wishes

Abhishek Maiti Thank you so much

I will try your suggestion