Schematic illustrations of the mechanisms that induce additive segregation to form interlayers in OPVs: (a) surface energy, (b) chemical interactions, (c) solubility, and (d) density or a concentration gradient.

Schematic illustrations of the mechanisms that induce additive segregation to form interlayers in OPVs: (a) surface energy, (b) chemical interactions, (c) solubility, and (d) density or a concentration gradient.