I have tried many times using different conditions by spin coat on ITO substrate.(Solvent is Toluene.) But could not make smooth film. Any one who has any good suggestion?
You can try to dissolve PCBM with chlorobencene. Additionally you need to know that is very important to do firstly an UVO treatment on the ITO surface in order to have a good wettability of the PCBM solution before spinning.
Thank you for your advice. Actually we also use the UVO treatment on the ITO surface. As you said I should try to dissolve PCBM with chlorobenzene which can dissolve PCBM easier than toluene. And do you think I should change the substrate as well?