Synthesis and Photovoltaic Properties of Oligothiophene Derivatives with Liquid Crystal Properties
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.
Yuan Ming Huang
L. Guan et al., "Synthesis and Photovoltaic Properties of Oligothiophene Derivatives with Liquid Crystal Properties", Materials Science Forum, Vols. 663-665, pp. 832-835, 2011