I have been trying to spin coat PEDOT:PSS onto a nano-textured silicon surface (nanopillars of 70 nm height). I'm using a water based dispersion and I always end up with the PEDOT:PSS layer deposited on top of the pillars instead completely filling up the space in between the nanopillars. Is there any to achieve a complete coating of the nanopillars?
Hi,
do you use a wetting agent?
How is the spacing between your pillars?
@Aditya Saha,
It is very likely that your PEDOT:PSS coating is much thinner than 70nm then. You may evaporate some water away inside PEDOT :PSS solution to make condescending solution. You would get thicker films to cover the pillars and gaps too.
Nina Feldhofer the spacing between nanopillars is around 56 nm.
Edit: I'm using X100 as a wetting agent and have also tried to make the substrate surface hydrophilic by treating it with a 3:1 H2O2:H2SO4 solution.
Xuhua Wang the thickness of the coating is actually around 110 nm. I have measured it with our SEM. I have even tried producing thicker coatings above 150 nm but the nanopillars somehow seem to be "supporting" the coating when I deposit it.
hm,
do you treat the samples before spincoating with HF acid, to get rid of the SiO2?
You could try different spin parameters.
Nina Feldhofer I try to spin-coat the PEDOT:PSS as soon as the samples are etched so there is little to no time for a new layer of SiO2 to form. I usually just treat the sample with HCl (which removes the mask) and piranha solution (to make the surface hydrophilic).
I have tried spin parameters that change the coating between 100 to 200 nm so far.
I'm currently thinking if there are ways to "force" PEDOT:PSS into the gaps. But I was wondering if anybody has already solved a problem like mine.
Strange.
You could look at my master thesis on page 17 I described the parameters I used to get the PEDOT:PSS into the nanopillars.
Maybe that helps
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