A new poly(arylene vinylene) derivative, poly(1,4-fluorenylenevinylene), with the advantages of poly(p-phenylene vinylene) and polyfluorene (PF), was designed, synthesized, and characterized. The polymer showed a defect-free structure and a number-average molecular weight of 32,600. The resulting polymer was thermally stable with a high glass-transition temperature (200 degrees C) and was readily soluble in common organic solvents. The polymer film showed a maximum emission at 515 nm and had a photolumineseence quantum yield of 58 +/- 5%. A cyclic voltammetry study revealed that the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of the polymer were 2.9 and 5.51 eV, respectively. The double-layer light-emitting-diode devices fabricated from the polymer emitted bright green light with a maximum around 515 nm. The device showed a maximum luminous efficiency of 0.13 cd/A and a maximum luminance value of 600 cd/m(2) at 17 V. (c) 2005 Wiley Periodicals, Inc.