A fluorene-co-carbazole-based copolymer (PFC) with an alkyl functional group at the 9-position, was designed and synthesized through a Suzuki polycondensation reaction. Excellent thermal stability and good optical performance were observed. High efficient blue light-emitting properties with purity color range at 410-480 nm were also obtained. The voltage-current curves revealed typical diode characteristics. The driving voltage of the PFC reached up to 5 V. The optical power-voltage characteristic curves showed that optical power was significantly dependant on the thickness of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline hole blocking layer. Thus, PFC is expected to be a promising pure blue light-emitting material and further experiments on electroluminescent properties, film morphology, and aggregation behaviors are in progress.