For the purpose of developing novel photovoltaic materials and organic photovoltaic devices with good performance characteristics, 5-cyano-2,2′:5′,2″-terthiophene (3T-CN) and 5-cyano -2,2′:5′,2″:5″,2″′-tetrathiophene (4T-CN) were synthesized. The 3T-CN and 4T-CN was donor-acceeptor type oligothiophene derivatives with liquid crystal properties. The rigid and flexible photovoltaic devices were fabricated using 3T-CN, 4T-CN and 3,4,9,10-perylenetertracarboxylic dianhydride (PTCDA). Comparision of the rigid device based on 4T showed that both rigid device glass-ITO/4T-CN/PTCDA/Al and flexible device PET-ITO/4T-CN/PTCDA/Al had higher short circuit current density (Isc) and power conversion efficiency (PCE) than that of glass-ITO/4T /PTCDA/Al. The -CN group played an important role in increasing Isc and PCE. It is due to that the mesogenic properties of 4T-CN, which enhances the efficiency by promoting forward interfacial electron transfer.