Bead Mill for Perovskite Tandem Solar Cells: The Nanoparticle Dispersion Step Most Guides Skip. Does perovskite solar cell manufacturing need a bead mill? Not for the perovskite absorber layer itself — that's a true molecular solution processed by spin-coating, blade-coating, or inkjet printing, not a particle dispersion. So where does dispersion equipment actually fit in? In the engineered nanoparticle additives that make advanced tandem cell architectures manufacturable at