Block copolymer as a nanostructuring agent for high-efficiency and annealing-free bulk heterojunction organic solar cells.

The addition of a block copolymer to the polymer/fullerene blend is a novel approach to the fabrication of organic solar cells. The block copolymer (P3HT-b-P4VP) is used as nanostructuring agent in the active layer. A significant enhancement of the cell efficiency is observed, in correlation with morphology control, both before (as-cast) and after the annealing process.

Design of well-defined monofunctionalized poly(3-hexylthiophene)s: toward the synthesis of semiconducting graft copolymers.

The post-functionalization of poly(3-hexylthiophene) (P3HT) via various synthetic routes is reported. Well-defined and monofunctionalized ω-thiol-terminated P3HT, ω-carboxylic acid-terminated P3HT, ω-acrylate-terminated P3HT, and ω-methacrylate-terminated P3HT are obtained in high yields through a straightforward procedure. From those, different novel P3HT-based graft copolymers are synthesized following two routes: "grafting onto" and "grafting through" (macromonomer polymerization) methods. The synthesis of three types of graft copolymers is described. Each one has "rod" P3HT-grafted side chains on a "coil" main chain, which can be polyisoprene, poly(vinyl alcohol), or poly(butyl acrylate). Each copolymer is characterized by size-exclusion chromatography and NMR.