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

Abstract

A novel copolymer, M-DCN-11, was synthesized via the Wittig reaction by incorporating a highly electronegative unit, 2,5-dicyano-1,4-phenylenevinylene (DCN-PV), alternately into the backbone of MEH-PPV. The copolymer was characterized by elemental analysis, cyclic voltammetry, UV, PL, FTIR, GPC, etc. The copolymer has good solubility in common organic solvents and can be cast as quality thin films. It shows a partially reversible oxidation process with the oxidation potential onset at 1.1 V (vs. SCE), which is 0.8 V higher than that of MEH-PPV (0.3 V vs. SCE). The reversible reduction process shows 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 been changed from a typical hole injection and transport material to a typical electron injection and transport material after incorporating the moiety bearing strong electron-withdrawing groups (DCN-PV) into the backbone.