1. Institute for Complex Materials, IFW Dresden, P.O. Box D-01171, 01069 Dresden, Germany
2. Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Sklodowskiej 34, Zabrze 41-819, Poland
3. Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
4. Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstraße 12, A-8700 Leoben, Austria
5. Department Materials Physics, Montanuniversität Leoben, Jahnstraße 12, A-8700 Leoben, Austria
6. College of Physics Optoelectronics and Energy, Soochow University, 215006 Suzhou, P. R. China