Synthesis and light‐emitting properties of a novel π‐conjugated poly[di( p ‐phenyleneethynylene)‐ alt ‐ ( p ‐phenylenecyanovinylene)] containing n ‐octyloxy side branches

A novel π‐conjugated poly[di( p ‐phenyleneethynylene)‐ alt ‐( p ‐phenylenecyanovinylene)] having n ‐octyloxy side chains (PPE‐C 8 PPE‐PPV) was prepared by polymerization of the monomer DEDB with BCN. Chemical structure of the polymer obtained was confirmed by 1 H NMR, FTIR, and EA. PPE‐C 8 PPE‐PPV had a molecular weight enough to fabricate the electroluminescent (EL) device, and showed a good organosolubility, excellent thermal stability, and film‐forming property. In UV absorption and PL spectra in film it showed a maximum at 430 and 543 nm, respectively, which appeared 5 and 41 nm longer wavelengths than that of the solution, respectively. HOMO, LUMO energy levels and band gap were determined to be −5.70, −3.29, and 2.41 eV, respectively. Two EL devices with low‐work function cathodes were fabricated with the structures of ITO/PEDOT/PPE‐C 8 PPE‐PPV/cathodes (LiF/Al and Mg:Ag/Ag). The both devices exhibited a bright green light emission at 545 nm and the maximum luminescence of 197 cd/cm 2 (LiF/Al) and 158 cd/cm 2 (Mg:Ag/Ag). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008