'Top- Down" nanophase reconstruction via a post-additive soaking process is first presented with various BHJ binary composites. By simply rinsing as-cast BHJ films with a solvent mixture containing a few traces of a nanophase-control reagent such as 1,8-diiodooctane, oversized fullerene-rich clusters (>100 nm in diameter) in the BHJ film are instataneously disassembled and entirely reorganized into finely intermixed donor/ acceptor nanophases (ca. 10 nm) with a 3D compositional homogeneity, without surface segregation.