2,5-Bis(4-bromophenyl)-3,4-diphenylthiophene was synthesized from benzyl chloride and sulfur and through the subsequent bromination of the intermediate 2,3,4,5-tetraphenylthiophene. It was condensed with 2,7-dibromo-9,9-dihexylfluorene via a nickel-mediated Yamamoto coupling reaction to afford a new series of statistical copolymers with various compositions. In addition, poly(9,9-dihexylfluorene) (PF) was synthesized under the same conditions for comparison. All the polymers were soluble in common organic solvents such as tetrahydrofuran (THF), chloroform, and dichloro methane. Their glass-transition temperatures increased with an increase in the tetraphenylthiophene (TPT) content in the polymers, and they were 63-149 degrees C. The solutions of the polymers in THF emitted intense blue light with a photoluminescence maximum at 418-440 nm and quantum yields of 0.32-0.62. Thin films of the polymers with TPT fractions lower than 20 mol % emitted blue-green light with two well-resolved peaks at 445 and 520 nm and an optical band gap of about 2.85 eV. A thin film of the polymer with a TPT fraction of 50 mol % emitted pure blue light with a maximum at 419 nm and an optical band gap of 3.28 eV. An enhancement of the light-emitting-diode brightness by a factor of similar to 8 with respect to that of PF was achieved in a polymer containing 5 mol % TPT. (c) 2006 Wiley Periodicals, Inc.