1. State Key Laboratory of Optoelectronic Materials and Technologies
2. School of Materials Science and Engineering/School of Physics
3. Sun Yat-sen University
4. Guangzhou 510275
5. P. R. China
6. School of Chemistry and Materials Engineering
7. Huizhou University
8. Huizhou 516007
9. School of Physics and Electronic Engineering
10. Guangzhou University
11. Guangzhou 510006