1. State
Key Laboratory of Luminescence Materials and Devices, Institute of
Optical Communication Materials, South China University of Technology, Guangzhou, Guangdong, China 510641
2. Department
of Electrical and Electronics Engineering, Department of Physics,
UNAM-Institute
of Materials Science and Nanotechnology, Bilkent University, Bilkent, Ankara, Turkey 06800
3. Department
of Electrical and Electronic Engineering, South University of Science and Technology, 1088 Xue-Yuan Road, Shenzhen, Guangdong, China 518055