New Series of Blue-Emitting and Electron-Transporting Copolymers Based on Fluorene

Abstract

A novel series of conjugated copolymers having oxadiazole, quinoline, quinoxaline, and phenylenecyanovinylene moieties in the main chain based on fluorene were synthesized in good yields by palladium-catalyzed Suzuki coupling reaction, a new approach different from the traditional polyhydrazide precursor route (oxadiazole-containing polymers), acid-catalyzed Friedlander condensation reaction (polyquinolines), and Knoevenagel condensation polymerization (poly(phenylenecyanovinylene)). The thermal, electrochemical, and optical properties of these copolymers were examined. All these polymers possess excellent thermal stability with glass transition temperatures of 114−208 °C and onset decomposition temperatures of 387−415 °C. Cyclic voltammetry studies reveal that these copolymers possess low-lying LUMO energy levels ranging from −3.01 to −3.37 eV and low-lying HOMO energy levels ranging from −6.13 to −6.38 eV and may be promising candidates for electron-transporting or hole-blocking materials in light-emitt...