Blue-light-emitting block copolymers based on polyfluorene (PF) and poly(triphenylamine) (PTPA) were synthesized for polymeric electroluminescent (EL) materials. PF with diphenylamine terminals were prepared by the Suzuki coupling polymerization, and converted to PTPA-block-PF-block-PTPA triblock copolymers by C-N coupling polymerization. The block copolymers with different substituents on PTPA segment, hydrophilic trioxyethylene (TEO) group (PF-PTPA-TEO) or hydrophobic n-butyl group (PF-PTPA-C4), were prepared in order to investigate their effect on device performance. The block copolymers showed relatively high HOMO levels compared with PF. EL devices based on the block copolymers showed higher luminance and current efficiency than that of PF homopolymer because of the improvement of hole injection by the introduction of PTPA segment. Modification by TEO group provided higher device performance than n-butyl group, indicating that PTPA segment segregated at the interface with PEDOT:PSS by the hydrogen-bonding interaction.