Transistor properties of two semiconducting polymers based on vinylene-bridged 5,6-difluorobenzo[c][1,2,5]thiadiazole (4T and 2TTT) and their structure-property relationship were investigated. Grazing incidence wide-angle X-ray scattering (GIWAXS) measurements revealed that both polymers formed an ordered edge-on orientation, but 4T has a higher crystallinity than 2TTT. As a result, the fabricated 4T-based organic field-effect transistor (OFET) exhibited a higher hole mobility of up to 0.079 cm(2) V-1 s(-1) than 2TTT-based OFET.