Design and synthesis of novel luminescent copolymers containing ionic conductive blocks on the skeletons

Three novel light-emitting copolymers containing ionic conductive segments tri(ethylene oxide) or crown-ether on the skeleton were synthesized by Wittig reaction. The copolymers were characterized by elemental analysis, FT-IR, 1H-NMR and gel permeation chromatography (GPC). The copolymers P2 and P3 containing tri(ethylene oxide) (TEO) segments can be dissolved in common organic solvents such as THF, chloroform, toluene, due to the good flexibility of TEO segments. The P1 containing crown-ether segments exhibit inferior solubility compared to P2 and P3 in some organic solvents because of the less flexibility of crown-ether segments. The introduction of ionic conductive blocks into the copolymer backbones has modified the optical properties, enhanced the processability of the copolymers. More importantly, it reduced the tendency of phase separation between the conjugated and ionic conductive polymers, which often occurs in the light-emitting electrochemical cells (LECs). The performances of light-emitting diodes (LEDs) by using the synthesized copolymers as emitters and LECs by using P2 as emitter were studied. The synthesis, characterization and electro-luminescent properties of the copolymers are reported in this paper.