What those treatments are doing - oxidizing the surface to generate hydroxyl, carboxyl, etc groups that are polar and hydrophilic.

You may be able to do the same thing with a liquid treatment - treat the surface with H2O2 for example. You will probably have to work out the time, temperature, concentration for optimal oxidation

thank you for the answer, i will try H2O2 with UV treatment James E Hanson

Hello, I would like to give an update regarding my previous question. Is it possible that the film has already formed, but I simply can't see it? I'm starting to feel hopeless.

Here are the methods I’ve tried so far:

Sample A:

• Multiple solvent baths using ultrasonication followed by drying (DI Water and IPA)
• Added 6% ethylene glycol (EG) to PEDOT:PSS
• Spin coated at 1000 rpm for 30 seconds

Sample B:

• Multiple solvent baths using ultrasonication followed by drying (DI Water and IPA)
• Added 10% IPA to PEDOT:PSS
• Spin coated at 1000 rpm for 30 seconds

Sample C:

• Multiple solvent baths using ultrasonication followed by drying (DI Water and IPA)
• Substrate treated in H₂O₂ under UV light chamber
• Added 10% IPA to PEDOT:PSS
• Spin coated at 1000 rpm for 30 seconds

I haven’t performed any advanced characterization yet—just tested with a simple double-probe multimeter. None of the samples showed any conductivity.

Is it possible that the film has actually formed, but it's too thin to be visible to the naked eye?

here the picture of sample C

and here the soource article of treatment for each sample come from

Sample A : Article Post-treated PEDOT:PSS doped with 2-ethoxyethanol films as t...

Sample B and C:

https://www.ossila.com/pages/how-to-spin-coat-pedot-pss