A new X-shaped pi-conjugated monomer comprising of fluorene units and anthracene units was synthesized, and it was used to fabricate the new X-shaped pi-conjugated polymers and investigate the properties of the new polymers. Using different molar ratios between such monomer and a fluorene monomer gave three polymers that showed higher absolute PL quantum yields than the linear polyfluorene (PF) in the solid state. After thermal annealing at 200 degrees C for 4 h, the linear PF showed an additional bathochromic emission at about 550 nm, whereas such red-shifted emission was fully eliminated for the X-shaped polymers. The electroluminescent devices based on the X-shaped polymers with a configuration of ITO/PEDOT:PSS/polymer/LiF/Ca/Al displayed blue emission with low turn-on voltage and high brightness. (C) 2008 Wiley Periodicals, Inc.