Two novel phenyl-substituted poly(p-phenylene vinylene) derivatives, poly{2-[3',4'-(2"-ethylhexyloxy)(3",7"dirnethyloctyloxy)benzene]-1,4-phe nylenevinylene) (EDP-PPV) and poly(2-[3',4'-(2"-ethylhexyloxy)(3",7 -dimethyloctyloxy)benzenel-5-methoxy-1,4-phenylenevinylene) (EDMP-PPV), and their copolymer, poly{2-[3',4'-(2"-ethylhexyloxy)(3",7"-dimethyloctyloxy)benzenel-1,4-phe nylene-vinylene-co-2-[3',4'-(2' -ethylhexyloxy)(3",7'-dimethyloctyloxy)benzenel-5-methoxy-1,4-phenyle-nevinylene) (EDP-co-EDMP-PPV; 4:1, 1:1, and 1:4), were successfully synthesized according to the Gilch route. The structures and properties of the monomers and the resulting conjugated polymers were characterized with H-1-NMR, C-13-NMR, elemental analysis, gel permeation chromatography, thermogravimetric analysis, ultraviolet-visible absorption spectroscopy, and photoluminescence and electroluminescence (EL) spectroscopy. The EL polymers possessed excellent solubility in common solvents and good thermal stability with a 5% weight loss temperature of more than 380 degrees C. The weight-average molecular weights and polydispersity indices of EDP-PPV, EDMP-PPV, and EDP-co-EDMP-PPV were 1.40-2.58 X 10(5), and 1.191.52, respectively. Double-layer light-emitting diodes with the configuration of indium tin oxide/ polymer/ tris (8-hydroxyquinoline)aluminum/A1 devices were fabricated, and EDP-co-EDMP-PPV (1:1) showed the highest EL performance and exhibited a maximum luminance of 1050 cd/m(2) at 19.5 V. (c) 2005 Wiley Periodicals, Inc.