Figure 19.

The molecular structures of PTB7-F20 and PC71BM (a); the conventional device structure of PSCs without incorporating any Fe₃O₄ magnetic nanoparticles (MNPs) (b); the conventional device structure of PSCs incorporated with Fe₃O₄ MNPs and aligned by an external magnetostatic field (c); the fabrication procedures of PSCs incorporated with Fe₃O₄ MNPs and aligned by an external magnetostatic field (d)–(f); BHJ active layer incorporated with Fe₃O₄ MNPs was spin-coated on a PEDOT:PSS-coated ITO substrate (d); and a ferromagnet was suspend above the surface of BHJ composite incorporated with the Fe₃O₄ MNP layer. The magnetic intensity was ~30–40 G, and the distance between the ferromagnet and BHJ composite layer was ~10 cm (e); oriented Fe₃O₄ MNPs inside BHJ active layer by an external magnetostatic field. In pre-devices (f), a drawing of a partial enlargement of the Fe₃O₄ MNP in (c), showing an antiparallel relation between the magnetic dipole (caused by the Fe₃O₄ crystal inside the particle) and electric dipole (caused by the difference in charge density between the inside Fe₃O₄ and outside organic coater) (g) (adapted from [132] with permission from Scientific Reports).