1. Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nürnberg, Martensstr. 7, D-91058 Erlangen, Germany
2. School of Semiconductor and Chemical Engineering, Chonbuk National University, 664-14, 1-ga Deokjin-dong, Deokjin-gu, Jeonju, Jeonbuk, 561-756, Republic of Korea
3. Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Bâtiment Lavoisier, Place Louis Pasteur, 1, 1348 Louvain-la-Neuve, Belgium