Have you tried two stage spin-coating? You can start slowly (e.g. 500 rpm) and then increase the spin-speed to e.g 3000 rpm, depending on your desired film thickness. If this does not work, you can try drop-casting or spraying PEDOT:PSS.

Hi sanjit,

I hope your CdS film withstand upto 200 degree Celsius . Usually PEDOT:PSS makes high contact angle (more than 100 degree)  with substrate. So you have to reduce the contact angle between the substrate and PEDOT:PSS. But the reduction of contact angle will not occur in normal condition. First you treat your CdS film substrate in oxygen plasma around 200 degree Celsius for 30 minutes, then you can spin coat the PEDOT:PSS over CdS film. This oxygen plasma treatment will reduce the contact angle (upto 20 degree).

My best wishes.

Hi Sanjit, 

I think you have to reduce  the surface tension of the film by add some drop of surfactant . 

@Majewski: yes i have tried that option too. but it didn't work..

@Rajagopal: yes i can try that one also. i think CdS will not be changed at 200 degree..