The Effects of Different Side Groups on the Properties of Polythiophene

To investigate the different side groups on the properties of polythiophenes (PTs), three kinds of samples, with alkyl [poly(3‐hexylthiophene), P3HT], alkoxy [poly(3‐hexyloxythiphene), P3HOT], aryl [poly(3‐phenylthiophene), P3PhT], were synthesized with chemically oxidized polymerization in the presence of FeCl₃. It was found that the molecular weight (MW) of PTs was influenced by the steric hindrance between side groups. The results of ultraviolet‐visible (UV‐Vis) and Fourier transform infrared (FT‐IR) spectra showed that P3HOT had a longer effective conjugation length than P3HT and P3PhT, due to both the stronger electron‐donating property of the alkoxy groups and the coplanar conformation of hexyloxy. Photoluminescence quenching was observed in P3HOT, which was attributed to energy transfer and photochemical reaction. Moreover, the thermal stability of PTs was dependent on the side group, too.

Keywords:

• conjugated polymer
• polythiophenes
• P3HT
• P3HOT
• P3PhT

5 Acknowledgements

This work was supported in part by DIC Corporation, Science and Technology Innovation Found of Sichuan University (Grant No. 2005CF09) and Student Innovation Found of Sichuan University (Grant No. 2006G003).