New fluorescent fluorenevinylene copolymers incorporating bis(phenyl)oxadiazole, triphenylamine, or both moieties were synthesized, characterized, and used as the emissive materials in efficient electroluminescent diodes. In dilute solutions, the copolymers had blue-green fluorescence with high quantum yields of 0.76-0.87. All the copolymers had high glass transition temperatures (T-g = 147-160 degrees C) and outstanding thermal stability. Light emitting diodes based on the neat copolymer thin films showed bright greenish-yellow electroluminescence, with luminances of up to 1360 cd/m(2), originating mostly from intramolecular charge-transfer excited states due to the presence of the donor/acceptor moieties in the copolymers. However, dilute (approximately 5 wt %) binary blends of the copolymers with poly(vinyl carbazole) gave stable blue electroluminescence (CIE = 0.17, 0.16) with higher luminances (1770-3400 cd/m(2)) and luminous efficiencies of up to 1.34 cd/A.