The procedure I have tried is as follows:
Firstly, I mixed PEDOT:PSS solution (Sigma Aldrich 0.5-1.0 % in water) in De-ionized water and did ultrasonication for 30 min.
Then magnetic stirring for 3 hours and again ultra-sonication for 30 min to homogenize the solution.
Then filtration using 0.45 um filter. The solution was filtered easily.
Then added ethylene glycol and again magnetic stirring overnight.
Finally did coating using spin coating at 2000 rpm for 30 secs.
The water, PEDOT:PSS, EG ratio was 52:41:7 % by weight of the solution.(taken from articles)
The main issue is that the film is very thin. How shall I form a 200 nm thick film. If I don't add water before filtration the PEDOT is not filtered.
@Dawar Ali,
Firstly, You shouldn't use the ultrasonic bath for polymers. The ultrasonic can damage the polymer chains.
Secondly adding DI water diluted your solution. Can you use 1 um PVDF filters for your PEDOT:PSS solutions?
To make thicker films you need to use low high-speed and high spin-speed for two steps. i.e. 500 rpm for 3 mins and 3000rpm for 20s.
Hope it helps.
@Dawar Ali,
Firstly, You shouldn't use the ultrasonic bath for polymers. The ultrasonic can damage the polymer chains.
Secondly adding DI water diluted your solution. Can you use 1 um PVDF filters for your PEDOT:PSS solutions?
To make thicker films you need to use low high-speed and high spin-speed for two steps. i.e. 500 rpm for 3 mins and 3000rpm for 20s.
Hope it helps.
Dear Dawar Ali,
I agree with Xuhua Wang, try to decrease the speed of spin until you get the desired thickness.
Best Regards
Hallo Dawar,
How do you treat your ITO substrates? Activation with oxygen or argon plasma could also help to obtain a higher film thickness...
Regards
Sebastian
Magnetic stirring is fine. A lot of publications didn't mention the details at all. Even you found some papers presented, you have work on your own procedures due to the variations of environment such as temperature and humidity.
In addition to the above good comments. Check how fresh is your PEDOT:PSS solution (expiration date). It is better to work with fresh solutions. If spin-coating homogeneity is not the necessarily demand you can also try doctor blade or casting techniques with or without some limiting edgings. You can also try to increase concentration of the parent solution.
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