Author(s)

Kenichi Sasaki, Yosei Shibata, Ming Lu, Yuji Yoshida, Reiko Azumi, Yasukiyo Ueda

Graduate School of Engineering, Kobe University, Hyogo, Japan.
Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Kanagawa, Japan.
National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki, Japan.

The effect of the molecular structure on photovoltaic performance was investigated by comparing two types of active layers. One is an active layer formed by sexithiophene (6T) and C₆₀ molecules which don’t have side chains. Another one is an active layer formed by a,ω-bis(2-hexyldecyl)sexithiophene (BHD6T) and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) molecules which have side chains. The 6T:C₆₀ active layer exhibited an excessive crystallization of 6T, which led to the low photovoltaic performance. In the BHD6T:PCBM active layer, the crystallization of BHD6T was suppressed. The crystallization of BHD6T was also easily controlled by thermal annealing, which led to improved photovoltaic performance.

Organic Photovoltaic Cells; Sexthiophene; Bulk Heterojunction; Morphology

K. Sasaki, Y. Shibata, M. Lu, Y. Yoshida, R. Azumi and Y. Ueda, "Effect of Side Chain of Oligothiophene Derivatives on Bulk Heterojunction Structure in Organic Photovoltaic Devices," Advances in Materials Physics and Chemistry, Vol. 3 No. 2, 2013, pp. 185-190. doi: 10.4236/ampc.2013.32026.