Synthesis and characterization of a novel light-emitting copolymer with improved charge-balancing property

A novel copolymer, M-DCN-11, was synthesized via the Wittig reaction by inc orporating a highly electronegative unit, 2,5-dicyano-1,4-phenylenevinylene (DCN PV), alternately into the backbone of MEH-PPV. The copolymer was char acterized by elemental analysis, cyclic voltammetry, UV, FL, FTIR, GPC, etc . The copolymer has good solubility in common organic solvents and can be c ast as quality thin films. It shows a partially reversible oxidation proces s with the oxidation potential onset at 1.1 V (vs. SCE),which is 0.8 V high er than that of MEH-PPV (0.3 V vs. SCE). The reversible reduction process s hows four peaks at -1.2, - 1.5, - 1.6, and -1.8 V (vs. SCE), respectively, starting from -0.9 V (vs. SCE). These data indicate that the polymer has be en changed from a typical hole injection and transport material to a typica l electron injection and transport material after incorporating the moiety bearing strong electron-withdrawing groups (DCN-PV) into the backbone. (C) 2000 Elsevier Science S.A. All rights reserved.