I have to use the Dr. blade method for coating of CuS nanoparticles over ITO glass substrate.
I have prepared a paste of particles, using a weak acidic solution of (H2SO4) and have coated by Dr. blade method. I get good coating of a thickness around 4 micrometer but the problem is it gets peeled off when it is dried.
I would recommend you first try to apply the thinner possible film. If you nottice better adhesion then do some more films by increasing the thickness gradually. Films derived from pastes, gels etc tend not to adhere to the substrate if thick. The evaporation of the solvent causes cracks and swelling.
Make suspension of nanoparticles in some suitable solvent (ethanol, acetone etc.) and then gradually spray on the ITO surface
Beginning with the substrate surface should be the first point to consider before altering any component or method. You can find numerous recipes to clean the ITO surface. When you sure about the surface cleaning method and surface itself. you may pass through the surface fictionalization a very thin(mono) layer of -OH on the surface of ITO can be very helpful with the peeling problem. Finally, if these are became to bu insufficient, shifting from a more volatile solvent to suspend your particles can cause less damage during the evaporation. If the above solutions fail to solve your problem, a very thin adhesion layer should be brought to table.
I don't know how you obtain your particles. But using a freshly prepared particles suspension will have better sticking ability then the awaited ones. I do not have the crystallization of the CuS but if it does not require elevated temperatures then they may be baked together as well.
Good Luck