For me your question is not clear. Do you want to have less scattering or a modification of the band structure. For colloidal particles size, aggregation and agglomerisation strongly influence especially the scattering (white) color of the colloidal particles. For ZnO the presence of light results in the reduction of the noble metal ions to the metal which can result in a "darking" of the particles. Bandgap can also be blue-shifted by the size.
Article Synthesis and testing of ZnO nanoparticles for photo-initiat...
I'm wondering if there is an analytical expression of gap or dielectric constant for the variation of Ag content Eg(x)(AgxZn1-xO). because here with three component Ag, Zn and Oxigen it's not clear. not like SiGe composite of two materials. If you can help in this subject.