1. Physical Chemistry; TU Dresden; Bergstr. 66b 01062 Dresden Germany
2. Carbon Research Laboratory; Liaoning Key Lab for Energy Materials and Chemical Engineering; State Key Lab of Fine Chemicals; Dalian University of Technology; Dalian 116024 P.R. China
3. Department of Physics, Department of Electrical and Electronics Engineering and UNAM-Institute of Materials Science and Nanotechnology; Bilkent University; TR-06800 Ankara Turkey
4. LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays; School of Electrical and Electronic Engineering and School of Physical and Mathematical Sciences; Nanyang Technological University; Singapore 639798 Singapore