Three new poly(fluorenevinylene) derivatives were synthesized, characterized, and used as emissive materials in light-emitting diodes (LEDs). They were synthesized by Heck coupling of 9,9-dihexyl-2,7-divinylfluorene with 2,7-dibromo-9,9-dihexyl-fluorene, 2,3-bis(4-bromophenyl)quinoxaline, or 2,5-bis(4-bromophenyl)-3,4-diphenylthiophene to afford the polymers F, Q, and T, respectively. Polymers F and Q had medium number-average molecular weights ((M) over bar (n) similar to 14,000) with relatively narrow polydispersity (1.3-1.6), while T was obtained as an oligomer ((M) over bar (n) similar to 4000). All polymers were soluble in common organic solvents, such as tetrahydrofuran (THF), chloroform, dichloromethane, and toluene. They emitted blue-greenish fluorescence light in dilute THF solution (444491 nm), with photoluminescence (PL) quantum yields of 0.32-0.54, and in thin film (453-488 nm). LEDs with the configuration of ITO/PEDOT-PSS/Polymer/Li:Al were fabricated and evaluated. The electroluminescence (EL) spectra of the Q and F polymers were very broad covering the blue-green-red region, whereas the spectrum of the polymer T was almost purely blue. The threshold electrical field for light emission of the devices was almost the same (similar to 1.75 MV/cm). The external quantum efficiency of the devices of polymers Q and F was about 1.0 x 10(-3)%, whereas that of polymer IT was similar to 3.0 x 10(-5)%. The fluorescence lifetime of polymers F and Q was significantly longer than that of the polymer T. (c) 2006 Wiley Periodicals, Inc.