New EL polymers possessing both hole and electron transporting units in the main chain are synthesized. The polymer prepared by palladium catalyzed Heck reaction of 3,5-bis-(4-bromophenyl)-4-phenyl-[1,2,4]triazole and [4-(2-ethylhexyloxy)-phenyl]-bis-(4’-vinylphenyl)amine show a large weight average molecular weight (Mw) (25,000) and small polydispersity index (PDI) (1.2). The oligomers synthesized by Wittig condensation have $M_w$ of 4,000 and PDI of 1.8. All the polymer and oligomers synthesized exhibit remarkable thermal stability with high decomposition temperature and high $T_g$ as determined by TGA and DSC under nitrogen atmosphere. The EL emission maximum peaks of the materials prepared are in the range of 535nm~560nm corresponding to green~yellowish-green. Among the three hole-blocking/electron transporting moieties, the 1,3,4-oxadiazole unit shows the best electron injection and transporting property.
We synthesized a series of bis [N-(p-X-phenyl) salicylaldiminato] zinc(II) and investigated their absorption, photoluminescence (PL) and electroluminescence (EL) properties. The p-substituted ligands Zn complex showed large bathochromic shift in introducing EWG on p-position which cause a lowering of the LUMO energy and blue-shift in EDG substituted complex, compared to unsubstituted ligand Zn complex. The p-substituted ligands Zn complexes result in decrease of electroluminescent efficiency and devices made with these materials have a higher operating voltage compared to device based on unsubstituted ligand Zn complex.