A series of semiconducting copolymers, poly[2,7-(9,9'-dioctylfluorene)-alt-5,5'-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PFDTBT), poly[2,2'-(9,9-dioctyl-9H-fluorene-2,7-diyl)dithiophene-alt-5,5'-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PFD2TBT), and their ter-polymers containing perylene units were synthesized using Suzuki coupling polymerization. The perylene units were introduced to improve the charge-transport ability by enhancing the pi-pi interaction between polymer chains. The resulting polymers were characterized by H-1 NMR, elemental analysis, DSC, and TGA. The synthesized polymers were soluble in common organic solvents, and formed smooth and uniform spin-coated thin films. All of the polymers studied were found to exhibit good thermal stability, losing less than 5% of their weight upon heating to approximately 350 degrees C. Perylene- containing polymers showed higher field-effect mobilities than the corresponding PFDTBT or PFD2TBT polymers because of the enhanced pi-pi interaction between polymer chains upon the introduction of perylene units. Bulk heterojunction solar cells were fabricated with configuration of ITO/PEDOT:PSS/polymer:PC71BM/TiOx/Al. The devices using the perylene-containing polymers showed higher short-circuit currents, and fill factors than the corresponding PFDTBT or PFD2TBT devices. One of the fabricated devices using a perylene-containing copolymer showed a maximum power conversion efficiency of 3.16%, with a short circuit current density of 9.61 mA/cm(2), open circuit voltage of 0.81 V, and fill factor of 41%.