Design, Synthesis, and Characterization of a −Donor−Bridge−Acceptor−Bridge- Type Block Copolymer via Alkoxy- and Sulfone- Derivatized Poly(phenylenevinylenes)

Abstract

A novel class of light harvesting conjugated block copolymers, with electron-donating conjugated blocks (D) connected to electron-accepting conjugated blocks (A) via non conjugated and flexible bridge chains (B), has been designed, synthesized, and characterized. Specifically, D is a decyloxy-substituted polyphenylenevinylene (C10−PPV). A1 and A2 are PPVs with sulfone (SO2) acceptor moieties substituted on every other phenylene unit. A1 carries two decyloxy groups on every phenylene unit, while in A2, half of the phenylene units are unsubstituted. The optical energy gaps are 2.24 eV for the donor block (D), 2.33 and 2.45 eV for A1 and A2 acceptor blocks. LUMO level offsets are 0.24 and 0.16 eV for D/A1 and D/A2 pairs, respectively. Comparing the photoluminescence from both films and solutions, very large red shifts (71 and 74 nm for A1 and A2 respectively) were observed in the two acceptor polymers. These red shifts in the emission spectra were more than twice as much as that observed for D (31 nm). The (...