I have been working lately with colloidal solutions.

I was adsorbing 100mm Ag particles with previously described procedure from 20ppm solution in one hour. Optically visible chnges was observed after particle deposition(blue or green washy colour). Further inestigation was reflection measurement. Two up to 2% reflectiom minima where found for between 300 - 500nm.
Also simulation parts where further developed. The optimal particle size where found.
For 0,5um thick silicon cell optimal diameter is 140nm.