1. National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering
2. Nanjing University
3. Nanjing 210093
4. China
5. Department of Optoelectronic Science
6. Harbin Institute of Technology at Weihai
7. Weihai 264209
8. School of Chemistry and Environment
9. South China Normal University
10. Guangzhou 510000